Efficient production of polar molecular Bose-Einstein condensates via an all-optical R-type atom-molecule adiabatic passage

We propose a scheme of "$R$-type" photoassociative adiabatic passage (PAP) to create polar molecular condensates from two different species of ultracold atoms. Due to the presence of a quasi-coherent population trapping state in the scheme, it is possible to associate atoms into molecules with a \textit{low-power} photoassociation (PA) laser. One remarkable advantage of our scheme is that a tunable atom-molecule coupling strength can be achieved by using a time-dependent PA field, which exhibits larger flexibility than using a tunable magnetic field. In addition, our results show that the PA intensity required in the "$R$-type" PAP could be greatly reduced compared to that in a conventional "$\Lambda$-type" one.Comment: 17 pages, 5 figures, to appear in New Journal of Physic

Calculations of the Far-Wing Line Profiles of Sodium and Potassium in the Atmospheres of Substellar-Mass Objects

At the low temperatures achieved in cool brown dwarf and hot giant planet atmospheres, the less refractory neutral alkali metals assume an uncharacteristically prominent role in spectrum formation. In particular, the wings of the Na-D (5890 \AA) and K I (7700 \AA) resonance lines come to define the continuum and dominate the spectrum of T dwarfs from 0.4 to 1.0 \mic. Whereas in standard stellar atmospheres the strengths and shapes of the wings of atomic spectral lines are rarely needed beyond 25 \AA of a line center, in brown dwarfs the far wings of the Na and K resonance lines out to 1000's of \AA detunings are important. Using standard quantum chemical codes and the Unified Franck-Condon model for line profiles in the quasi-static limit, we calculate the interaction potentials and the wing line shapes for the dominant Na and K resonance lines in H$_2$- and helium-rich atmospheres. Our theory has natural absorption profile cutoffs, has no free parameters, and is readily adapted to spectral synthesis calculations for stars, brown dwarfs, and planets with effective temperatures below 2000 Kelvin.Comment: 14 pages, Latex, 7 figures in JPEG format, accepted for publication in the Astrophysical Journa

Photoassociation of cesium atoms into

We report absorption measurements in pure cesium vapor at high temperatures, when triplet absorption bands in the spectral interval 540–560 nm emerge within the singlet molecular bands which slowly diminish due to efficient thermal dissociation. The absorption bands have been identified as stemming from extrema in the ${\rm Cs}_2$ 3\;^3\Pi_{\rm g}-a $^3\Sigma_{\rm u}^+$ difference potential curve. We performed a quasiclassical simulation which agrees well with experimental observation. Since the $\rm Cs_2$ a $^3\Sigma_{\rm u}^+$ state is only weakly bound, the observed absorption bands at 543.5 and 557 nm represent free-bound transitions or the photoassociation process

Rubidium pure long-range ion-pair molecules

The \chem{Rb_2} ion-pair satellite band located in the blue wing of the rubidium second resonance doublet line was observed in the absorption measurements of a dense rubidium vapor. The observed satellite band was identified as a long-range ion-pair state, by using the \chem{Rb_2} long-range potential curves based on ab initio calculations. In order to perform the semiclassical spectral simulations of the observed satellite band, the relevant \chem{Rb_2} long-range potential curves and corresponding molecular dipole oscillator strengths were calculated using the asymptotic method. The importance of the observed satellite band (long-range ion-pair state) is discussed in connection with the formation of \chem{Rb_2} ultracold molecules

SATELLITE BANDS OF K, Rb AND Cs RESONANT LINES AS FRANCK-CONDON WNDOWS TO INTERMEDIATE LONG-RANGE MOLECULES

References: 1. R. Beuc, S. Miloevi, M. Movre, G. Pichler and D. Vea, FIZIKA (YU), 14 (1982) 345-349. 2. Awan and Lewis, J. Phys. B:Atom. Mol. Phys 3. D. Vea, R. Beuc, S. Miloevi and G. Pichler, The European Physical Journal D. I (1998). 4. O. Dulier, R. Kosloff, F. Masnou-Seeuws and G. Pichler, Journal of Chemical Physics, 107 (1997) 10633.Author Institution: Institute of PhysicsVery far quasi-static wings of self-broadened first resonance lines of potassium(1) rubidium (2) and cesium (3) are rich in different types of satellite bands that stem from various avoided crossings. Detailed experimental study of the absorption and emission profiles in the region of satellite bands should reveal the possibility of existence of bound states in the so called intermediate long-range region. These bound states lie above the corresponding asymptotic level at internuclear distances of about 2-3 nm(4). They can be used to reach much higher bound intermediate long-range states of K2, Rb2 and Cs2 molecules at moderate or ultra-cold temperatures

Cusp satellite bands in the spectrum of Cs

We report measurements and a theoretical explanation of the cusp-shaped satellite bands in the blue wing of the cesium D2 resonance line which have been observed for the first time. The bands are identified as $1 ^{3}\!\Pi _{g}(2_{g},1_{g},0_{g}^{+},0_{g}^{-})\leftarrow a ^{3}\Sigma _{u}^{+}(1_{u},0_{u}^{+})$ transitions where the upper state dissociates into the 6 2P$_{3/2} + 6 ^{2}$S1/2 atomic asymptote. The experiment has been performed using a standard absorption setup, computer controlled data acquisition and computer data processing. We have shown that the peculiar shape of the $1 ^{3}\!\Pi _{g}(0_{g}^{+})-a ^{3}\Sigma _{u}^{+}(1_{u})$ difference-potential curve is solely responsible for the spectrum containing the cusp-shaped satellite bands. The appearance of these satellite bands has been discussed and explained relating the theory of satellite bands to the catastrophe theory. The shape of the line wing and of the satellite bands have been calculated using the Fourier transform technique. To ensure a more stringent comparison between the experimental and the theoretical spectrum, we have analyzed and compared the derivatives of the measured and the calculated satellite band shape. On the contrary to the customary direct comparison between the measured and the calculated absorption coefficient, the derivative clearly shows all differences and resemblances between satellite band profiles. The degree of coincidence of the experimentally observed and the theoretically calculated satellite band shape can be used as an ultimate check on the assessment of the quality of potential-energy curves involved in the formation of satellite bands

Rb

We investigated collisional processes involved in the population of the Rb2 diffuse band through resonant excitation of Rb atoms. Near-infrared (780 nm) and violet (420 nm) diode lasers were used for the Rb first (\rm 5\,^{2}S_{1/2}\to 5\,^{2}P_{3/2}) and second (\rm 5\,^{2}S_{1/2}\to 6\,^{2}P_{3/2}) resonant doublet excitations. Laser induced fluorescence spectra were detected and investigated at different rubidium densities, buffer gas pressures and excitation wavelengths