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Ultracold Polar Molecules: Formation and Collisions

Joint Workshop with Harvard/MIT Center for Ultracold Atoms

January 8-10, 2004

Organizers: John Doyle, Jeremy Hutson, and Roman Krems

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 Schedule

Thursday, Friday, Saturday

Online Talks

Abstracts

  

 

Online Talks

[Talks can be viewed with the free RealPlayer from http://www.real.com]

 Abraham

Bergeman

Bigelow

 Bochinski

Bohn 

 Chandler

 Cote

 DeMille

 DiRosa

Doyle 

Dulieu 

Forrey

 Friedrich

Gianturco

 Gould, H  

Groenenboom

Hinds

 Hulet

Hutson

Jeung

 Kotochigova

Krems

Masnou-Seeuws 

Meijer

Naduvalath 

 Rempe

Stone

Stwalley

Szalewicz

Szczesniak

 Weidemuller
       

 

Workshop Participants

Prof. Eric R. Abraham
Department of Physics and Astronomy,
University of Oklahoma
440 W. Brooks St.
Norman, OK 57019
abraham@nhn.ou.edu

Prof. Thomas H. Bergeman
Dept of Physics and Astronomy
SUNY Stony Brook
46 Twisting Drive
Lake Grove, NY 11755
thbergeman@notes.cc.sunysb.edu
 
Prof. Nicholas P. Bigelow
Department of Physics and Astronomy
University of Rochester
Bausch & Lomb 206
Rochester, NY 14627-0171
nbig@lle.rochester.edu
 
Dr. Jason Bochinski
JILA
University of Colorado
UCB 440
Boulder, CO 80309-0440
bochinsk@jilau1.colorado.edu
 
Prof. John Bohn
JILA
University of Colorado
UCB 440
Boulder, CO 80309
bohn@murphy.colorado.edu
 
Dr. Alexei Buchachenko
Laboratory of Molecular Structure and Quantum Mechanics
Department of Chemistry,
Moscow State University
119992 Moscow, Russia
alexei@classic.chem.msu.su

Dr. Steven J. Buelow
Los Alamos National Laboratory
C-PCS, MS J567
Los Alamos, NM 87545
buelow@lanl.gov

Prof. Grzegorz Chalasinski
Department of Chemistry
University of Warsaw
00-927 Warsaw, Poland
chalbie@tiger.chem.uw.edu.pl

Dr. David W. Chandler
Sandia National Laboratories
7011 East Avenue
Livermore, CA 94550
chand@sandia.gov
 
Prof. Robin Cote
Department of Physics
University of Connecticut
2152 Hillside Road
Storrs, CT 06269-3046
rcote@phys.uconn.edu

Prof. David DeMille
Yale University
Physics Department
PO Box 208120
New Haven, CT 06520
david.demille@yale.edu

Dr. Michael Di Rosa
Los Alamos National Lab
Physical Chemistry and Applied Spectroscopy
MS J567
Los Alamos, NM 87545
mdd@lanl.gov
 
Prof. John Doyle
Harvard University
Physics Department
Cambridge, MA 02138
doyle@physics.harvard.edu
 
Dr. Olivier Dulieu
Laboratoire Aime Cotton, CNRS
Bat. 505, Campus d'Orsay
91405 Orsay Cedex, France
olivier.dulieu@lac.u-psud.fr
 
Prof. Robert C. Forrey
Berks-Lehigh Valley College
Penn State University
Reading, PA 19610
rcf6@psu.edu
 
Dr. Bretislav Friedrich
Department of Molecular Physics,
Fritz Haber Institute of the Max Plank Society,
Faradayweg 4-6
D-14195, Berlin, Germany
bretislav.friedrich@fhi-berlin.mpg.de
 
Prof. Franco A. Gianturco
Dipartimento di Chimica
Universita di Roma "La Sapienza"
Citta Universitaria
00185 Rome, Italy
fa.gianturco@caspur.it

Dr. Harvey A. Gould
Lawrence Berkeley National Laboratory
One Cyclotron Road, MS 71-259
Berkeley, CA 94720
gould@lbl.gov

Prof. Phillip L. Gould
University of Connecticut
Department of Physics, U-3046
2152 Hillside Road
Storrs, CT 06269-3046
gould@uconnvm.uconn.edu
 
Dr. Gerrit C. Groenenboom
University of Nijmegen
Toernooiveld 1,
6525 ED Nijmegen, The Netherlands
gerritg@theochem.kun.nl
 
Prof. Edward Hinds
Imperial College London
213, Blackett Laboratory
Prince Consort Road
London, SW7 2BW, United Kingdom
ed.hinds@imperial.ac.uk

Prof. Randy Hulet
Department of Physics & Astronomy - MS 61
Rice University
Houston, TX 77005
randy@atomcool.rice.edu
 
Prof. Jeremy M. Hutson
Department of Chemistry
University of Durham
Durham, DH1 3LE, UK
J.M.Hutson@durham.ac.uk
 
Prof. Gwang-Hi Jeung
Theoretical Chemistry
University of Provence
Case 521, Campus de St-Jerome
Marseille, 13397 Marseille
jeung@lctmm.u-3mrs.fr
 
Prof. Daniel Kleppner
Department of Physics
M.I.T.
77 Massachusetts Avenue
Cambridge, MA 02139
kleppner@MIT.EDU
 
Dr. Svetlana A. Kotochigova
NIST
100 Bureau Dr., Stop 8423
Gaithersburg, MD 20899
svetlana@nist.gov
 
Dr. Roman Krems
ITAMP
60 Garden Street, MS 14
Cambridge, MA 02138
rkrems@cfa.harvard.edu

Dr. Francoise Masnou-Seeuws
Laboratoire Aime Cotton
Campus d'Orsay, bt 505
91190 ORSAY Cedex , France
francoise.masnou@lac.u-psud.fr

Prof. Gerard Meijer
Fritz-Haber-Institut
Max-Plank-GES
Faradayweg 4-6
D-14195, Berlin, Germany
meijer@fhi-berlin.mpg.de
 
Prof. Balakrishnan Naduvalath
Department of Chemistry
University of Nevada Las Vegas
4505 Maryland Parkway, Box 454003
Las Vegas, NV 89154-4003
naduvala@unlv.edu

Prof. Gerhard Rempe
Max-Planck-Institut fur Quantenoptik
Hans-Kopfermann-Str. 1
D-85748 Garching bei Mnchen, Germany
gerhard.rempe@mpq.mpg.de

Prof. Dan M. Stamper-Kurn
Department of Physics
University of California Berkeley
366 LeConte Hall 7300
Berkeley, CA 94720
dmsk@socrates.Berkeley.edu
 
Dr. Andrei Stolyarov
Department of Chemistry
Moscow State University
pazyuk@phys.chem.msu.ru
 
Dr. Anthony J. Stone
University Chemical Laboratory
University of Cambridge
Lensfield Road
Cambridge, CB2 1EW, United Kingdom
ajs1@cam.ac.uk
 
Prof. William C. Stwalley
University of Connecticut
Department of Physics, U-3046
2152 Hillside Road
Storrs, CT 06269-3046
stwalley@uconnvm.uconn.edu

Prof. Krzysztof Szalewicz
Department of Physics
121 Sharp Laboratory
University of Delaware
Newark, DE 19716
szalewic@udel.edu

Prof. Maria M. Szczesniak
Department of Chemistry
Oakland University
Rochester, MI 48309
maria@ouchem.chem.oakland.edu

Prof. James J. Valentini
Department of Chemistry
Columbia University
3000 Broadway, MC 3120
New York, NY 10027
jjv1@columbia.edu
 
Prof. Ad van der Avoird
University of Nijmegen
Toernooiveld 1,
Nijmegen, 6525 ED The Netherlands
avda@theochem.kun.nl
 
Prof. Matthias Weidemüller
Institute of Physics
Freiburg University
Hermann-Herder-Str. 4
79100 Freiburg, Germany
m.weidemueller@physik.uni-freiburg.de
 

ATTENDEES

Mishkatul Bhattacharya
Department of Physics and Astronomy
University of Rochester
Rochester, NY 14627-0171
 
Dr. Enrico Bodo
c/o Prof. Gianturco
Department of Chemistry
University of Rome La Sapienza
Citta Universitaria, NEC
P. le A. Moro 5
Rome, 00185 Italy
bodo@caspur.it
 
Dr. Subhadeep Gupta
University of California
366 Le Conte Hall
Berkeley, CA 94720
deep@socrates.berkeley.edu
 
Chris Haimberger
Department of Physics and Astronomy
University of Rochester
Rochester, NY 14627-0171
 
Prof. Dudley R. Herschbach
Chemistry Department
Harvard University
12 Oxford Street
Cambridge, MA 02138
 
Jan Kleinert
Department of Physics and Astronomy
University of Rochester
Rochester, NY 14627-0171
 
Prof. Mats Larsson
Department of Physics
AlbaNova University Center
Stockholm University
Stockholm, SE-106 91 Sweden
mats.larsson@physto.se
 
Ms. Sabrina Leslie
University of California
1640 Scenic Avenue
Apt 1
Berkeley, CA 94709
sleslie@socrates.berkeley.edu
 
Dr. Robert Moszynski
University of Warsaw
Pasteura 1
Warsaw, PL-02-093 Poland
rmoszyns@tiger.chem.uw.edu.pl
 
Jessie Petricka
Yale University
PO Box 208120
217 Prospect Street
New Haven, CT 06511
jessie.petricka@yale.edu
 
Mrs. Elizabeth A. Taylor-Juarros
University of Connecticut
2152 Hillside Road
Storrs, CT 06269-3046
eliztj@phys.uconn.edu
 
Mr. Christopher Ticknor
JILA
University of Colorado, Boulder
UCB 440
Boulder, CO 80309
ticknor@colorado.edu
 
CUA
 
Dr. James Anglin
Massachusetts Institute of Technology
77 Massachusetts Ave., 26-251
Cambridge, MA 02139
janglin@mit.edu
 
Wes Campbell
Harvard University
17 Oxford Street
Cambridge, MA 02138
wes@cua.harvard.edu
 
Dimitri Egorov
Physics Department
Harvard University
17 Oxford Street
Cambridge, MA 02138
egorov@fas.harvard.edu
 
Prof. Wonho Jhe
School of Physics
Seoul National University
Seoul, 151-747 South Korea
whjhe@snu.ac.kr
 
Dr. Jack G.E. Harris
Harvard-MIT CUA
17 Oxford Street
Cambridge, MA 02138
jack@cua.harvard.edu
 
Prof. Wolfgang Ketterle
MIT
77 Massachusetts Avenue, 26-243
Cambridge, MA 02139
ketterle@mit.edu
 
Dr. Aaron Leanhardt
MIT
77 Massachusetts Avenue, 26-269
Cambridge, MA 02139
ael@mit.edu
 
Steve Maxwell
Harvard/CUA
17 Oxford St.
Cambridge MA 02138
maxwell@fas.harvard.edu
 
Jongchul Mun
Massachusetts Institute of Technology
77 Massachusetts Avenue, 26-269
Cambridge, MA 02139
jcmun@mit.edu
 
Mr. Sebastian Raupach
RLE at MIT
77 Massachusetts Avenue
Cambridge, MA 02139-4307
raupach@mit.edu
 
Dr. Michele Saba
MIT
77 Massachusetts Avenue, 26-429
Cambridge, MA 02139
msaba@mit.edu
 
Mr. Young-Il Shin
MIT-CUA
77 Massachusetts Avenue, 26-255
Cambridge, MA 02139
yishin@mit.edu
 
Dr. Dominik Schneble
Massachusetts Institute of Technology
77 Massachusetts Avenue, 26-267
Cambridge, MA 02139
schneble@mit.edu
 
Dr. James K. Thompson
MIT
77 Massachusetts Avenue, 26-229
Cambridge, MA 02139
jkthomps@mit.edu
 
 
Dr. Laurens van Buuren
Harvard University
17 Oxford Street
Cambridge, MA 02138
buuren@fas.harvard.edu
 
Mr. Martin W. Zwierlein
MIT
77 Massachusetts Avenue
Cambridge, MA 02139
zwierlei@mit.edu

 

Workshop Schedule

January 8, 2004, Thursday

Phillips Auditorium (all day)
8:30-8:45 WELCOME

A.  Linking Ultracold Atoms - Part I
8:45-9:15 D. DEMILLE: Production of Ultracold Polar Molecules via Photoassociation
9:15-9:45 T. BERGEMAN: Modeling RbCs Spectra, Photoassociation, and Cold Molecule Formation
9:45-10:15 Coffee
10:15-10:45 N. BIGELOW: Photoassociation of Different Atomic Species in a Magneto-Optical Trap
10:45-11:15 R. COTE:  LiH and NaH Formation via Photoassociation
11:15-11:45 S. KOTOCHIGOVA: Photoassociative Formation of Ultracold Polar KRb Molecules
11:45-12:15 R. HULET:  Conversion of an Atomic Fermi Gas to a Molecular Bose Gas
 12:15-2:00 LUNCH

B.  Accurate Calculations of Interaction Forces between Atoms and Molecules
2:00-2:40 A. STONE:  Long-Range Forces between Small Polar Molecules
2:40-3:10 J. HUTSON:  Interactions between Polar Molecules and Alkali Metal Atoms
3:10-3:40 COFFEE
3:40-4:10 M. SZCZESNIAK:  Interactions Involving Transition Metal Atoms
4:10-4:40 G-H. JEUNG:  Short and Medium Range Interatomic Potentials of the Polar Molecules
 4:40-5:00 STRETCH
5:00-5:30 K. SZALEWICZ:   Perturbation Theory of Intermolecular Interactions Based on Density-Functional Description of Monomers
5:30-6:00  G. GROENENBOOM: Ab Initio Computation and Representation of Potentials for Open Shell Complexes
 6:00-7:00 RECEPTION IN PERKIN LOBBY

January 9, 2004, Friday

Phillips Auditorium (all day)

C.  Cold Collisions and Cooling of Molecules
9:00-9:30 J. DOYLE:  Cold Molecule Collisions and Trapping with Buffer-gas Loading
9:30-10:00 R. KREMS: Mechanisms of Zeeman Transitions in Collisions of Molecules with Atoms
10:00-10:30 COFFEE
10:30-11:00 H. GOULD:  Progress towards Molecule-Molecule Scattering Experiments at Collision Energies below 1 K
11:00-11:30 B. NADUVALATH :  Chemistry in the Extreme Quantum Limit
11:30-12:00 R. FORREY:  Ultracold He+CO Collisions Involving Highly Excited Rotational and Vibrational Initial States
12:00-12:30 F. GIANTURCO:  The Big Chill: Inelastic and Reactive Collisions at Ultralow Temperatures
12:30-2:00 LUNCH

D.  Slowing and Manipulating Molecules with Electric Fields
2:00-2:30 G. MEIJER:  Manipulation of Molecules with Electric Fields
2:30-3:00 J. BOCHINSKI:   Cold Free Radical Molecules in the Laboratory Frame
3:00-3:30 COFFEE
3:30-4:00 J. BOHN: Ultracold Polar Molecules in External Fields
 4:00-4:30 E. HINDS:  Slowing Heavy, Ground-State Molecules Using an Alternating Gradient Decelerator
 4:30-5:00 STRETCH
5:00-5:30 G. REMPE:   Guiding of Polar Molecules in Two-Dimensional Static and Time-Varying Electric Fields
5:30-6:00 M. DiROSA: Experimental Progress in Laser-Cooling Molecules

January 10, 2004, Saturday

Phillips Auditorium (all day)

E.  Alternative Methods of Ultracold Molecule Formation
9:00-9:30 E. ABRAHAM:  Sources and Studies of Ultracold Atoms and Molecules without Laser Cooling
9:30-10:00 D. CHANDLER:  Subkelvin Cooling NO Molecular Beams via "Billiard-Like" Collisions with Argon
10:00-10:20 COFFEE
10:20-10:50 B. FRIEDRICH:  Cool Molecular Micro-Beams, Frigid Clusters, and Gelid Molecular Diffraction Images
10:50-11:20 M. WEIDEMULLER: Formation of Cold Homo- and Heteronuclear Alkali Molecules on Helium Nanodroplets
11:20-11:40 COFFEE

F.  Linking Ultracold Atoms - Part II
11:40-12:10 F. MASNOU-SEEUWS:  Coherent Control and Cold Molecules
12:10-12:40 W. STWALLEY: Studies of Heteronuclear Alkali Metal Dimers
12:40-1:10 O. DULIEU:  Photoassociation and Ultracold Molecule Formation with Heteronuclear Alkali Systems
1:10 ADJOURN

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Abstracts

 Abraham

Bergeman 

Bigelow

 Bochinski

Bohn 

 Chandler

 Côté

 DeMille

 DiRosa

Doyle 

Dulieu 

Forrey 

 Friedrich

Gianturco

 Gould, H  

 Groenenboom

Hinds 

 Hulet

Hutson 

Jeung 

 Kotochigova

Krems 

Masnou-Seeuws 

Meijer 

Naduvalath 

 Rempe

Stone 

 Stwalley

Szalewicz 

Szczesniak 

 Weidemüller
       

 Sources and Studies of Ultracold Atoms and Molecules without Laser Cooling

Eric Abraham

Department of Physics and Astronomy
University of Oklahoma
440 W. Brooks St.
Norman, OK 57019

Cold and ultracold samples of atoms and molecules can be formed by filtering the desired cold fraction from a thermal source. This extraction process must take place on a time scale faster than the mean collision time to prevent the loss of the cold fraction due to collisions.
We present experimental and theoretical results on the production of cold nitric oxide (NO) using curved guides utilizing the Stark and Zeeman effects. Stark traps, designed with non-zero field minima to eliminate non-adiabatic loss, can be loaded from such a source utilizing dark-state trapping, which loads a conservative trap by optically pumping particles into an internal state that sees a stronger confining potential. Such trapped molecules may lead to new molecular collision studies and facilitate the search for the electric dipole moment of the electron.

 

Modeling RbCs Spectra, Photoassociation, and Cold Molecule Formation

Tom Bergeman (SUNY Stony Brook) in collaboration with A.Kerman, J.Sage, S.Sainis and D. DeMille (Yale U.); C.Fellows and R.Gutterres (Rio de Janeiro); and C.Amiot (Orsay)

Abstract PDF

 

Photoassociation of Different Atomic Species in a Magneto-Optical Trap

N. P. Bigelow, C. Haimberger, J. Kleinert and M. Bhattacharya


Department of Physics and Astronomy and
Laboratory for Laser Energetics
The University of Rochester

In Rochester we have investigated cold collisions in mixed-species MOTs. Our work has included Na+Cs, Na+Rb and Rb+Cs and has covered both trap loss measurements and photoassociative ionization studies. Recently, we have also presented calculations of the s-wave scattering length for Na+Rb.

In this talk I will describe our experimental work on photoassociation of heteronuclear pairs in the MOT.

References

S. B. Weiss, M. Bhattacharya, N. P. Bigelow, Calculation of the interspecies s-wave scattering length in an ultracold Na-Rb vapor, Phys. Rev. A, 68, 042708 (2003).

Y. Young, R. Ejnisman, J. Shaffer, N. P. Bigelow, Heteronuclear Hyperfine-State Changing Cold Collisions, Phys. Rev. A, 62, 055403 (2000).

J. Shaffer, W. Chalupczak, N. P. Bigelow, Trap Loss in a Two-Species Na-Cs Magneto-optical Trap: Intermultiplet Mixing in Heteronuclear Ultracold Collisions, Phys. Rev. A, Rapid Comm., 60, R3365 (1999).

J. Shaffer, W. Chalupczak and N. P. Bigelow, Photoassociative Ionization of Ultra-Cold Heteronuclear Molecules, Phys. Rev. Lett., 82 1124 (1999).

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Cold Free Radical Molecules in the Laboratory Frame

J. R. Bochinski, Eric R. Hudson, H. J. Lewandowski, and Jun Ye

JILA, National Institute of Standards and Technology, and
Department of Physics, University of Colorado
University of Colorado, Boulder, Colorado 80309-0440

Neutral free radicals are an attractive class of particles for cold molecule research. Important as a focal point of study in physical chemistry, astrophysics, and combustion physics, these highly reactive molecules typically possess large electric and magnetic dipole moments, thus allowing a variety of means for manipulation of their external degrees of freedom. We report experimental measurements on the production of cold hydroxyl radical (OH) molecules utilizing Stark deceleration. In situ laser-induced fluorescence (LIF) detection enables detailed observations of the pulsed molecular packet within the decelerator itself as the OH molecules undergo longitudinal phase-space evolution, driven by their interaction with the spatially inhomogeneous electric fields. Numerical simulations of the slowing process provide agreement with experimental results, demonstrating good understanding and control of the cooled molecules. We now have the capability of producing a packet of 106 - 109 molecules with an arbitrary translational velocity in the range of a few meter/second to a few hundred meter/second in the lab frame, with a temperature of ~ 15 mK in the moving frame. Furthermore, these molecules can now be observed in an electro-static quadrupole trap. Our latest results in the related trap dynamics will be discussed, as well as new directions towards magnetically trapping the hydroxyl radicals.

 

Ultracold Polar Molecules in External Fields

John Bohn

JILA
University of Colorado
UCB 440
Boulder, CO 80309

The response of ultracold matter to externally applied electric and magnetic fields has tremendous importance for influencing the properties of this matter, on both the microscopic and macroscopic scales. Molecules that possess both a magnetic dipole moment and a permanent electric dipole moment present unique opportunities in this regard, as they can be acted on jointly by both kinds of fields. One such molecule, the OH radical,is the subject of this talk. I will discuss the variation of collision rates in an ultracold OH gas in the presence of E and B fields simultaneously. As a preliminary application, I note that inelastic scattering to exothermic channels can be somewhat mitigated in the presence of two fields.

Subkelvin Cooling NO Molecular Beams via "Billiard-Like" Collisions with Argon

David W. Chandler, Jim Valentini and Mike Elioff 

Sandia National Laboratories
7011 East Avenue
Livermore, CA 94550      

We report the cooling of nitric oxide molecules using a single collision between an argon atom and the molecule. We have produced significant numbers (108-109 molecules cm-3 per quantum state) of translationally cold NO(2P1/2,j'=7.5) molecules in a specific quantum state with an upper-limit RMS laboratory velocity of 15*1 m s-1, corresponding to a 406*23 mK upper-limit of temperature, in a crossed molecular beam apparatus. The technique, which relies on a kinematic collapse of the velocity distributions of the molecular beams for the scattering events that produce cold molecules, is general and independent of the energy of the
colliding partner.

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LiH and NaH Formation via Photoassociation

R. Cote*, E. Taylor-Juarros, and K. Kirby

*Department of Physics
University of Connecticut
2152 Hillside Road
Storrs, CT 06269-3046

A variety of experimental techniques have been employed to create a number of ultracold molecules, including CaH, Na2, K2, Cs2, Rb2, and CO. The recent realization of Bose-Einstein condensates of molecules of Li2 and K2 opens up the possibility of accomplishing the same with polar molecules, for which novel effects are predicted to occur. In addition, such ultracold polar molecules could enhance the possibility of detecting the electron dipole moment or be used in quantum computing.

The alkali hydride molecules have significant dipole moments in their electronic ground states, and thus it is interesting to explore the creation of these molecules through stimulated radiative association. We present calculations of the formation rate of ultracold LiH and NaH, using the most accurate molecular potentials and dipole moments available. We explore two possible schemes to produce ultracold polar molecules via stimulated emission starting from the continuum: a one-photon and a two-photon process. We show that these polar molecules can be produced in selected vibrational and rotational states by stimulated radiative association in a mixture of ultracold hydrogen and alkali metal atoms.

 

Production of Ultracold Polar Molecules via Photoassociation

D. DeMille, A. J. Kerman, J. M. Sage, and S. Sainis, and T. Bergeman*

Physics Department
Yale University

*Department of Physics and Astronomy
SUNY Stony Brook

 

Abstract PDF

 Experimental Progress in Laser-Cooling Molecules

M. D. Di Rosa, R. K. Sander, and S. J. Buelow

Los Alamos National Laboratory
Los Alamos, New Mexico 87545

At Los Alamos, we are studying a particular class of diatomics-the alkaline-earth monohydrides (e.g. BeH and CaH)-that have Rydberg transitions similar to the 2P1/2, 3/2¨2S1/2 transitions of alkali atoms and appear suited to laser cooling. As a class, the A¨X transitions of the alkaline-earth monohydrides possess characteristics that are favorable for Doppler-cooling, including a (nearly) diagonal Franck-Condon array and good spectral isolation of the transitions that form the cooling cycle. We will show how a beam of such molecules can be laser-decelerated, and report the status of our experiments for the particular case of CaH. We will also consider the use of dc-Stark spectroscopy for Doppler-shift compensation (akin to methods of R. Knize et al. and L. Windholz et al. applied to alkali atoms) and for creating an optical trap.

Cold Molecule Collisions and Trapping with Buffer-gas Loading

John Doyle

Harvard University
Physics Department
Cambridge, MA 02138

       Molecules possess a number of features that could greatly expand the possibilities for study of new interactions, collective quantum effects, collisional processes, fundamental tests and chemical processes. This is due to 1) the strong interactions between the dipole moments of polar molecules, 2) the rotational and vibrational internal structure of all molecules, and 3) the easily orientable internal electric field of many polar molecules. The promise of cold and ultracold dipolar molecules will only be realized when samples can be prepared with at least approximately the same ease in which we now prepare atomic samples. Several approaches towards trapping of polar molecules, the key first step toward studying ultracold polar molecules at high density, have already succeeded: direct cooling of molecules via a buffer gas, mechanical slowing of a pulsed molecular beam with electric fields and photoassociation of alkali atoms. Over the past 5 years we have developed the technique of buffer-gas cooling and loading of molecules into magnetic traps, starting with the first trapping of a molecule, CaH, in 1998. Buffer-gas cooling relies solely on elastic collisions (thermalization) of the species-to-be-trapped with a cryogenically cooled helium gas and so is independent of any particular energy level pattern. Using buffer-gas loading, paramagnetic atoms (Cr, Eu, Mo) and molecules (CaH) have been trapped and several other species have been cooled (Na, Ti, Y, Zr, Sc, PbO, and NH) and their collisional properties studied. The process is found to be highly efficient; the number of trapped species limited only by the production method. The general method and recent results will be discussed including the cooling of molecules directly from a molecular beam and the creation of cold molecular beams.

 

Photoassociation and Ultracold Molecule Formation with Heteronuclear Alkali Systems

O. Dulieu (in collaboration with S. Azizi, M. Aymar)

Laboratoire Aime Cotton
CNRS, Bat 505
Campus d'Orsay 91405
Orsay Cedex, France

In recent years, several groups succeeded in making samples of ultracold molecules at temperatures below 1 milliKelvin, using photoassociation of cold atoms. The photoassociation process forms molecules in an excited electronic state, which stabilize themselves by spontaneous emission into a bound level of the ground electronic state.

The efficiency of cold molecule formation is mainly influenced by the relative position and long-range behaviour of molecular potentials involved. For homonuclear systems, the photoassociated electronic state varies as R-3 at large distances R, while the ground electronic state varies as R-6.

In a previous work, quantitative analysis of photoassociation and cold molecule formation rates has been proposed for Cs2 [1]. In this work, we present our quantum calculations for these rates, in the case of heteronuclear alkali molecules, in order to provide quantitative information for future experiments. In such systems, both excited and ground electronic states vary as R-6.
We compare our results to the experimental rates obtained with cesium dimer, as well as with the previous theoretical study by Wang and Stwalley [2]. Predictions for the vibrational distribution of the molecules produced in the electronic ground state are also discussed.

References

[1] C. Drag et al, IEEE J. Quant. Electron., 36, 1378 (2000).
[2] H. Wang and W. C. Stwalley, J. Chem.Phys, 108, 5767 (1998).

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Ultracold He+CO Collisions Involving Highly Excited Rotational and Vibrational Initial States

R. C. Forrey

Penn State University
Berks Lehigh Valley College
Reading, PA 19610-6009

 

Abstract PDF

 

Cool Molecular Micro-Beams, Frigid Clusters, and Gelid Molecular Diffraction Images

Bretislav Friedrich

Department of Molecular Physics
Fritz-Haber-Institut der Max-Planck-Gesellschaft
Faradayweg 4-6, D-14195 Berlin, Germany

Abstract PDF

 

The Big Chill: Inelastic and Reactive Collisions at Ultralow Temperatures

Franco A. Gianturco and Enrico Bodo

Department of Chemistry and INFM
The University of Rome "La Sapienza"
Piazzale A. Moro 5
00185 Rome (Italy)

Abstract PDF

 Progress towards Molecule-Molecule Scattering Experiments at Collision Energies below 1 K

Harvey Gould

MS 71-259 Lawrence Berkeley National Laboratory
Berkeley CA, 94720

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Ab Initio Computation and Representation of Potentials for
Open Shell Complexes

Gerrit C. Groenenboom

Institute of Theoretical Chemistry
University of Nijmegen
Toernooiveld 1
6525 ED Nijmegen, The Netherlands.
gerritg@theochem.kun.nl
 

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Slowing Heavy, Ground-State Molecules Using an Alternating Gradient Decelerator

Edward Hinds

Imperial College London
213, Blackett Laboratory
Prince Consort Road
London, SW7 2BW, United Kingdom

We have decelerated heavy molecules in their ground state using switched electric fields. The decelerator exhibits the axial and transverse stability required to decelerate the molecules to
rest. This experiment uses a pulsed supersonic beam of cold 174YbF molecules. Time varying electric field gradients have previously been used to decelerate light polar molecules in excited states. This work significantly extends the range of molecules amenable to this powerful method of cooling and trapping.

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Conversion of an Atomic Fermi Gas to a Molecular Bose Gas

R. G. Hulet, K. E. Strecker, and G. P. Partridge

Department of Physics & Astronomy
Rice University
Houston, TX 77005

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 Interactions between Polar Molecules and Alkali Metal Atoms

Jeremy M. Hutson and Pavel Soldan

Department of Chemistry, University of Durham, Durham, DH1 3LE, United Kingdom

The interaction between Rb and NH is investigated as a prototype for interactions between alkali metal atoms and stable molecules. Such interactions are relevant to current attempts to achieve sympathetic cooling of molecules in atomic traps. We have carried out ab initio electronic structure calculations to characterize the surfaces. The strength of the interaction is found to depend very strongly on the spin states involved. If the Rb and NH are spin-aligned, and interact on a quartet surface (4A''), the interaction is dominated by dispersion forces and is relatively weak, with a well depth of 0.078 eV. If the two species are not spin-aligned, however, the lowest doublet surface (2A'') has a very much stronger interaction potential (well depth 1.372 eV) because it is an ion-pair state with an attractive Coulomb interaction at short range. The dispersion-bound doublet state crosses the ion-pair state at conical intersections at linear geometries. In this case, strong collisions can occur via a harpoon mechanism. This effect may be undesirable for sympathetic cooling, because it may enhance reorientation and three-body collision rates, but it might also be used for production of extremely polar ultracold molecular complexes. For RbNH, there are electronically excited states correlating with Rb (2P) that have reasonable Franck-Condon factors to both the low-energy continuum state Rb (2S) + NH(3_) and the ion-pair bound state Rb+NH. It may thus be possible to form the very polar Rb+NH­ species by stimulated Raman pumping or even by spontaneous emission.

Similar deeply bound ion-pair states exist for other alkali atom ­ molecule pairs such as Rb­OH, but not for Rb­HF.

 Short and Medium Range Interatomic Potentials of the Polar Molecules

Gwang-Hi Jeung (*)

Theoretical Chemistry and Molecular Modelling
Case 521 (CNRS UMR6517)
Facultes de St-Jerome
13397 Marseille Cedex, France

There has been a remarkable progress in quantum chemical calculations of the interaction potential for short and medium range internuclear distances during the last decades. Presently, large-scale calculations can be done for simple systems including diatomic and triatomic cases using high-level ab initio methods, such as the extensive multi-reference configuration interactions or the high-order coupled-cluster models, either with or without the effective-core potentials. However, the resulting potential curves or surfaces is still not accurate enough to be compared with those of the high-resolution laser spectroscopic data. So, one has to do some kind of adjustments to the theoretical data, as the experimental data are insufficient to cover a wide range of the internuclear distances in most cases.

There are several reasons for the inaccuracy of ab initio calculations for small systems. One category concerns the inaccurate description of the atomic states: the atomic spectra, the ionization potential and the electron affinity. The second concerns the insufficient treatment of the molecular effects, which originates mostly from the basis set problems: the polarization functions and the linear dependencies. Here, I am going to discuss the problems belonging to the first category, in particular for the polar molecules.

In this case, it is essential to describe both the ionization potential and the electron affinity of the composing atoms accurately to obtain a good molecular potential around the potential well. I am going to discuss some historical studies done in this field and illustrate the problem with some polar molecules.

(*) E-mail: jeung@lctmm.u-3mrs.fr

 Photoassociative Formation of Ultracold Polar KRb Molecules

S. Kotochigova

National Institute of Standards and Technology
100 Bureau Drive, Stop 8423
Gaithersburg, MD 20899

 

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Mechanisms of Zeeman Transitions in Collisions of Molecules with Atoms

Roman Krems
 
ITAMP
60 Garden Street, MS 14
Cambridge, MA 02138

The efficiency of buffer-gas loading of molecules in a magnetic trap depends critically on rate constants for Zeeman transitions in collisions of molecules with buffer-gas atoms at subKelvin temperatures. We present results of rigorous calculations of cross sections and rate constants for Zeeman relaxation in collisions of NH and CaH molecules with He atoms
and demonstrate that the Zeeman transitions in rotationally ground-state diatomic molecules occur through coupling between molecular rotational levels. The ground electronic state of CaH is of doublet-sigma symmetry and NH is a triplet-sigma molecule. We show that

The Zeeman relaxation in doublet-sigma molecules has a three-step mechanism that involves transitions to asymptotically closed rotationally excited levels and the action of the spin-rotation interaction in the excited states. There are no matrix elements that couple the Zeeman energy levels in collisions of doublet-sigma molecules with structureless atoms like He. The Zeeman transitions in collisions of triplet-sigma molecules with He atoms are induced by direct couplings due to the anisotropy of the electrostatic atom - molecule interaction and the spin-spin interaction in the molecule. The efficiency of the Zeeman
transitions in triplet-sigma molecules is determined by the strength of the coupling between the N=0 and N=2 rotational energy levels. As a result, the Zeeman relaxation in homonuclear diatomic molecules should be similar to that in heteronuclear molecules.

A discussion of predissociation of wan der Waals complexes in a magnetic field (Zeeman predissociation) will be given, if time permits.

 Coherent Control and Cold Molecules

Francoise Masnou-Seeuws

Laboratoire Aime Cotton
bât. 505
Campus d'Orsay
91405 Orsay, France

In collaboration with Eliane Luc-Koenig, Christiane Koch, Pascal Naidon (Orsay),
Mihaela Vatasescu (Orsay-Bucarest), Ronnie Kosloff (Jerusalem)

 

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 Manipulation of Molecules with Electric Fields

Gerard Meijer

Fritz-Haber-Institut der Max-Planck-Gesellschaft
Faradayweg 4-6, D-14195 Berlin, Germany
e-mail: meijer@fhi-berlin.mpg.de

During the last few years we have been experimentally exploring the possibilities of ma-nipulating neutral polar molecules with electric fields [1]. Arrays of time-varying, inhomo-geneous electric fields have been used to reduce in a stepwise fashion the forward velocity of molecules in a beam. With this so-called 'Stark decelerator', the equivalent of a LINear ACcelerator (LINAC) for charged particles, one can transfer the high phase-space density that is present in the moving frame of a pulsed molecular beam to a reference frame at any desired velocity; molecular beams with a computer-controlled (calibrated) velocity and with a narrow velocity distribution, corresponding to sub-mK longitudinal temperatures, can be produced. These decelerated beams offer new possibilities for collision studies, for instance, and enable spectroscopic studies with an improved spectral resolution; first proof-of-principle high-resolution spectroscopic studies have been performed. These decelerated beams have also been used to load neutral ammonia molecules in an electrostatic trap at a density of (better than) 107 mol/cm3 and at temperatures of around 25 mK. In another experiment, a decelerated beam of ammonia molecules is injected in an electrostatic storage ring. The package of molecules in the ring can be observed for more than 50 distinct round trips, corresponding to 40 meter in circular orbit and almost 0.5 sec. storage time, sufficiently long for a first investigation of its transversal motion in the ring. A scaled up version of the Stark-decelerator and molecular beam machine has just become operational, and has been used to produce decelerated beams of ground-state OH and electronically ex-cited (metastable) NH radicals. The NH radical is particularly interesting, as an optical pumping scheme enables the accumulation of decelerated bunches of slow NH molecules, either in a magnetic or in an optical trap. By miniaturing the electrode geometries, high electric fields can be produced using only modest voltages. A micro-structured mirror for neutral molecules that can rapidly be switched on and off has been constructed and used to retro-reflect a beam of ammonia molecules with a forward velocity of about 30 m/s. This holds great promise for miniaturizing the whole decelerator, trap and storage ring for future applications.

References
[1] H.L. Bethlem and G. Meijer, Int. Rev. Phys. Chem. 22, 73 (2003)

 Chemistry in the Extreme Quantum Limit

Balakrishnan Naduvalath

Department of Chemistry
University of Nevada Las Vegas
4505 Maryland Parkway
Las Vegas, NV 89154

 

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 Guiding of Polar Molecules in Two-Dimensional Static and Time-Varying Electric Fields

G. Rempe, T. Junglen, P.W.H. Pinkse, S. Rangwala, T. Rieger

Max-Planck Institute for Quantum Optics
Hans-Kopfermann-Str. 1,
D-85748 Garching, Germany

The Stark interaction of neutral polar molecules with inhomogeneous electric fields is exploited to select slow molecules from a thermal reservoir and guide them through a series of differential pumping stages into an ultrahigh-vacuum chamber. A linear quadrupole with a curved section selects molecules with small longitudinal and transverse velocities. The source operates in a continuous manner and can, in principle, be operated with any molecule. Molecules in high-field seeking states are guided in static fields, while both high and low-field seeking molecules are guided simultaneously in time-varying electric fields.

 Long-Range Forces between Small Polar Molecules

Dr. Anthony J. Stone
 
University Chemical Laboratory
University of Cambridge
Lensfield Road
Cambridge, CB2 1EW, United Kingdom
 
 

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 Studies of Heteronuclear Alkali Metal Dimers

William C. Stwalley

Department of Physics, Unit 3046
University of Connecticut
Storrs, CT 06269-3046

A variety of theoretical and experimental studies of heteronuclear alkali metal dimers are underway at the University of Connecticut:

1. Comparison of theoretical exchange and Coulomb interactions with
spectroscopically-based X1_+ and a3_+ potentials [1].
2. Calculation of radiative transition probabilities, lifetimes and dipole
moments for all X1_+ vibrational levels of 39K85Rb [2]. Note the shortest
radiative lifetime is 1.00x103s for =56.
3. Calculation of weakly bound long-range wells for interactions of one
excited 2S alkali atom with a second ground state alkali atom [3].
4. High temperature laser spectroscopy and theoretical analysis of excited
states [4].
5. Ultracold photoassociative spectroscopy in a dual species MOT (39K, 85Rb) [5].

These studies, supported by NSF (1-3, 5) and the NATO Science for Peace Program (4) will be briefly described.

[1] With W.T. Zemke. See e.g. W.T. Zemke and W.C. Stwalley, J. Chem. Phys. 114,
10811 (2001).

[2] With W.T. Zemke. See W.T. Zemke and W.C. Stwalley, J. Chem. Phys., in press.

[3] With B. Normand. See B. Normand, W.T. Zemke, R. Côté, M. Pichler, and W.C.
Stwalley, J. Phys. Chem. A 106, 8450 (2002) for the formalism used.

[4] With R. Ferber et al. (Univ. of Latvia) and A. Stolyarov et al. (Moscow State Univ.).
See e.g. M. Tamanis et al., J. Chem. Phys. 117, 7980 (2002).

[5] With D. Wang, J. Qi, M. Stone, O. Nikolayeva and P.L. Gould.

 Perturbation Theory of Intermolecular Interactions Based on Density-Functional Description of Monomers

Krzysztof Szalewicz, Alston J. Misquitta, and Bogumil Jeziorski

Department of Physics
University of Delaware
Newark, DE 19716
 

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Interactions Involving Transition Metal Atoms

M. M. Szczesniak* and G. Chalasinski**

*Department of Chemistry, Oakland University, Rochester MI 48309, USA and
**Faculty of Chemistry, University of Warsaw, Pasteura 1, Warsaw, Poland


The interactions between open-shell atoms with a non-zero angular momentum and closed-shell atoms or molecules are characterized by multiple potential energy curves/surfaces which result from a removal of the electronic degeneracy of an open-shell atomic term. In the main-group atoms, this splitting is often quite substantial and can be easily rationalized either in terms of the strength of the electrostatic interactions on different potential energy surfaces, or in terms of a varying exchange repulsion. This type of electronic anisotropy has major implications on the collisional properties of the interacting atoms. By comparison, in the interactions of the d-electron transition-metal atoms with a closed-shell moiety this splitting is very weak. The reasons for the suppression of this type of electronic anisotropy will be discussed.

Ab initio calculations of the low-lying states of the first-row d-electron transition metals Sc(2D) and Ti(3F) interacting with He will be presented. The Sc(2D) + He interaction gives rise to three non-relativistic states 2S, 2P, and 2D. These states are very shallow and their well-depths vary in a narrow range of 3.8 - 4.1 cm-1. By comparison, in a D-term main-group atomic interaction, O(1D) + He, an analogous spread is over 40 cm-1. These disparities are apparent at the Hartree-Fock level of theory, indicating that the exchange repulsion is the root cause. One possible reason for the quenching of the anisotropy of the exchange-repulsion in transition metals, Sc and Ti, is the presence of the 4s electrons. The radius of the 4s sub-shell is much larger than that of the 3d sub-shell. The results for the interaction of a di-cation, Sc2+(2D) with He, where the 4s electrons are absent, will be presented. Preliminary results for the low-lying states of Ti(3F) + He indicate that the Ti interactions are even more isotropic than those of Sc.

 Formation of Cold Homo- and Heteronuclear Alkali Molecules on Helium Nanodroplets

Matthias Weidemuller[1], Marcel Mudrich[1], Oliver Bunermann[2], Frank Stienkemeier[2]

[1] Institute of Physics, Albert-Ludwigs-Universitat Freiburg, 79104 Freiburg, Germany
[2] Faculty of Physics, Universitat Bielefeld, 33615 Bielefeld, Germany

Superfluid Helium nanodroplets are doped with combinations of different alkali atoms (Li, Na, Rb, Cs). The atoms form molecules on the surface of the droplets which thermalize at the droplet temperature (T < 0.4 K) [1]. Different detection schemes (photoionization, laser-induced fluorescence and laser- induced beam depletion) are employed to reveal detailed information on the binding and the internal states of the molecules. Besides the formation of heteronuclear alkali dimers (LiCs, NaCs) we observe CsHe* exciplexes at excitation frequencies close to the cesium D1 and D2 transitions. Characteristic features in the cesium excitation spectrum are identified as Cs3 trimer states.

Excitation spectra of the heteronuclear alkali dimers in the frequency range of a tunable Ti:Sa-laser are recorded. The observed vibrational progressions are identified in terms of transitions within the triplet ground-state manifold. Analysis of the spectra yields constraints to ab initio potential curves from literature. Laser-induced desorption of the heteronuclear dimers is observed which opens perspectives to create a beam of free, cold heteronuclear molecules for precision spectroscopy or to provide a source for deceleration and trapping of polar molecules.

[1] F. Stienkemeier, W.E. Ernst, J. Higgins, and G. Scoles, Phys.Rev.Lett. 74, 3592 (1995)

 

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ACCOMMODATIONS

Listed below are the names and, where possible, the 800 numbers of hotels and a bed and breakfast agent to assist you in getting accommodations for the upcoming Workshop.

It is especially important that you book a room for the workshop right away as the fall is a very busy time in Cambridge, and you might not be able to get one of the cheaper bed and breakfasts. As housing is expensive in Cambridge/Boston, you may wish to get together with a friend and share a room.

The hotels are within walking distance of the Institute, the Sheraton a short walk and the other two longish walks. They all are on bus routes:

Best Western Homestead Inn, 220 Alewife Brook Parkway, Cambridge,
MA 02138; (617) 491-1890 or 1 (800) 528-1234

Harvard Manor House, 110 Mt. Auburn St., Cambridge, MA 02138
(617) 864-5200

Sheraton-Commander, 16 Garden St., Cambridge, MA 02138; (617) 547-4800 or 1 (800) 325-3434

Boston Reservations/Boston Bed & Breakfast, Inc., 1643 Beacon St., Suite
23, Waban, MA 02168; (617) 332-4199; Fax: (617) 332-5751; e-mail: bostonreservations@bostonreservations.com

All of this information plus more is on the ITAMP web page at http://www.cfa.harvard.edu/itamp under "living accommodations."

We recommend your booking through Boston Reservations/Boston Bed & Breakfast, as in most cases they can get you a room at lower cost than a cold call will get you. If you tell them you are attending a workshop at the Harvard Observatory, they will make every effort to book you at a bed and breakfast, or hotel if you wish, in close proximity. They have many comfortable accommodations in the surrounding neighborhood, and previous workshop participants have been very satisfied with their rooms.

We also strongly advise your not bringing or renting a car. There is no visitor parking at the Observatory and most on-street parking in Cambridge is designated for Cambridge residents only. There are few places in Cambridge and Boston that aren't easily accessible by public transportation and we recommend it highly.
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 Online registration for invited participants:

http://cfa-www.harvard.edu/cgi-bin/conf_reg/reg.pl?conf_id=ITAMPJAN04