Our group is located in
rooms 001 and 007A of the Physics
Building at the University
of Connecticut.
Our research focuses on atom, molecule,
and photon interactions, particularly few atom systems.
Molecules of special interest are those of the alkali
metals, e.g. Li2, Na2, K2,
Rb2, Cs2, NaK, NaRb, KRb. Areas
of special interest include:
I. Laser Spectroscopy and Photodynamics.
The excitation of atomic or molecular fluorescence using
one or more lasers (usually tunable) is now a well known
technique which we have applied to a variety of systems
with emphasis on alkali metal molecules. Of particular
interest are studies of atomic interactions and potential
energy curves, obtained accurately from spectroscopic
data, including accurate dissociation energies, long
range interactions and quantitative evaluation of the
breakdown of the Born-Oppenheimer approximation (separation
of electronic and nuclear motion); and absolute radiative
transition probabilities (bound-free as well as bound-bound)
for one or more photon transitions in diatomic species
such as Na2. Recent emphasis has been on
double and triple resonance techniques which circumvent
many constraints due to selection rules. In addition,
novel studies of state-selected photodissociation and
the polarization of atomic fluorescence resulting from
photodissociation are underway.
II. Laser Ionization Spectroscopy
and Laser-Produced Plasmas. The production of
atomic and molecular ions upon irradiation by one or
more lasers has been studied, again with emphasis on
alkali metals. Of particular interest are energy transfer
and ionization in metal vapors, e.g. the competition
between associative ionization, ion pair formation,
fluorescence and other processes in collisions of excited
alkali metal atoms; and plasmas produced by low power
(less than 1 milliwatt) CW laser or modest power pulsed
laser irradiation. These unique high electron density
(1014/cm3), low electron temperature
(0.1 eV) plasmas have been produced in all alkali vapors
by interesting feedback mechanisms. In addition, novel
studies of multiphoton excitation of doubly excited
autoionizing states are underway.
III. Ultracold Atoms and Molecules.
Exciting new laser techniques allow cooling and trapping
of atoms at microKelvin temperatures. Such atoms show
extreme quantum behavior (deBroglie wavelength is proportional
to T-1/2). Molecular photoassociative spectra
of colliding ultracold atoms provide unique and direct
information on the long range interactions between atoms
and related atomic properties (atomic lifetime, dipole
matrix elements, electron affinity, etc.). We have obtained
1011 atoms/cm3 at 0.3 mK in a
"dark spot" magneto-optic trap and used this trap to
observe the first ultracold photoassociative spectra
of K atoms. We have extended this spectroscopy from
single photon to multiphoton and produced transitionally
ultracold molecules (T~0.3 mK). More recently we extended
the ultracold photoassociative spectroscopy to Cs atoms,
to produce ultracold Cs2 molecules and to
ultimately study cold chemical reactions, e.g. Cs(7p1/2)
+ H2(v=0, J=0) -> CsH (v=0, J=0) + H,
which is endoergic by 6±2K.
Professor Stwalley co-founded the Interdisciplin
ary Laser Science Conference and is active in the American
Physical Society, the American Chemical Society, and
the Optical Society of America. His phone, fax, and
e-mail are: (860) 486-4924, (860) 486-3346,
w.stwalley@uconn.edu.
Click here to read recent articles from
Che
mical and Engineering News (October 2, 2000, p.47)
and Physics
Today (Vol. 53, issue 9, p.46) on ultracold molecules.
Click
here for an abbreviated curriculum vitae of Professor
Stwalley.
Click
here for a full list of publications and patents.
Click
here for a full CV.
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