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Register a new userThe coupling of the X$^{1}Sigma ^{+}$ and a$^{3}Sigma ^{+}$ states of KRb
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A comprehensive study of the electronic states at the 4s+5s asymptote in KRb is presented. Abundant spectroscopic data on the astate state were collected by Fourier-transform spectroscopy which allow to determine an accurate experimental potential energy curve up to 14.8 AA . The existing data set (C. Amiot et al. J. Chem. Phys. 112, 7068 (2000)) on the ground state Xstate was extended by several additional levels lying close to the atomic asymptote. In a coupled channels fitting routine complete molecular potentials for both electronic states were fitted. Along with the line frequencies of the molecular transitions, recently published positions of Feshbach resonances in $^{40}$K and $^{87}$Rb mixtures (F. Ferlaino et al. Phys. Rev. A 74, 039903 (2006)) were included in the fit. This makes the derived potential curves capable for an accurate description of observed cold collision features so far. Predictions of scattering lengths and Feshbach resonances in other isotopic combinations are reported.
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We present the first spectroscopic studies of the $C ^1Sigma^+$ electronic state and the $A ^1Sigma^+$ - $b ^3Pi_{0^+}$ complex in $^7$Li - $^{85}$Rb. Using resonantly-enhanced, two-photon ionization, we observed $v = 7$, 9, 12, 13 and $26-44$ of the $C ^1Sigma^+$ state. We augment the REMPI data with a form of depletion spectra in regions of dense spectral lines. The $A ^1Sigma^+$ - $b ^3Pi_{0^+}$ complex was observed with depletion spectroscopy, depleting to vibrational levels $v=0 rightarrow 29$ of the $A ^1Sigma^+$ state and $v=8 rightarrow 18$ of the $b ^3Pi_{0^+}$ state. For all three series, we determine the term energy and vibrational constants. Finally, we outline several possible future projects based on the data presented here.
We combined high-resolution Fourier-transform spectroscopy and large-scale electronic structure calculation to study energy and radiative properties of the high-lying (3)1{Pi} and (5)1{Sigma}+ states of the RbCs molecule. The laser-induced (5)1{Sigma}+(4)1{Sigma}+(3)1{Pi}-A(2)1{Sigma}+ b(1)3{Pi} fluorescence (LIF) spectra were recorded by the Bruker IFS-125(HR) spectrometer in the frequency range { u} 5500 to 10000cm-1 with the instrumental resolution of 0.03 cm-1. The rotational assignment of the observed LIF progressions, which exhibit irregular vibrational-rotational spacing due to strong spin-orbit interaction between A1{Sigma}+ and b3(Pi) states was based on the coincidences between observed and calculated energy differences. The required rovibronic term values of the strongly perturbed A-b complex have been calculated by a coupled-channels approach for both 85Rb133Cs and 87Rb133Cs isotopologs with accuracy of about 0.01 cm-1, as demonstrated in A. Kruzins et al. [J. Chem. Phys. 141, 184309 (2014)]. The experimental energies of the upper (3)1(Pi) and (5)1{Sigma}+ states were involved in a direct-potential-fit analysis performed in the framework of inverted perturbation approach. Quasirelativistic ab initio calculations of the spin-allowed (3)1{Pi},(5)1{Sigma}+- (1-4)1{Sigma}+(1-3)1{Pi} transition dipole moments were performed. Radiative lifetimes and vibronic branching ratios of radiative transitions from the (3)1{Pi} and (5)1{Sigma}+ states were evaluated. To elucidate the origin of the {Lambda}-doubling effect in the (3)1{Pi} state, the angular coupling (3)1{Pi}-(1-5)1{Sigma}+ electronic matrix elements were calculated and applied for the relevant q-factors estimate. The intensity distributions simulated for the particular (5)1{Sigma}+(3)1{Pi}-A-b LIF progressions have been found to be remarkably close to their experimental counterparts.
Imidogen (NH) radicals are magnetically trapped and their Zeeman relaxation and energy transport collision cross sections with helium are measured. Continuous buffer-gas loading of the trap is direct from a room-temperature molecular beam. The Zeeman relaxation (inelastic) cross section of magnetically trapped electronic, vibrational and rotational ground state imidogen in collisions with He-3 is measured to be 3.8 +/- 1.1 E-19 cm^2 at 710 mK. The NH-He energy transport cross section is also measured, indicating a ratio of diffusive to inelastic cross sections of gamma = 7 E4 in agreement with the recent theory of Krems et al. (PRA 68 051401(R) (2003))
We report the first observation of photoassociation to the 2(1)Sigma(g)(+) state of 85Rb2 . We have observed two vibrational levels (v=98, 99) below the 5s1/2+5p1/2 atomic limit and eleven vibrational levels (v=102-112) above it. The photoassociation---and subsequent spontaneous emission---occur predominantly between 15 and 20 Bohr in a region of internuclear distance best described as a transition between Hunds case (a) and Hunds case (c) coupling. The presence of a g-wave shape resonance in the collision of two ground-state atoms affects the photoassociation rate and lineshape of the J= 3 and 5 rotational levels.
We observe magnetic trapping of atomic nitrogen (14^N) and cotrapping of ground state imidogen (14^NH, X-triplet-Sigma-). Both are loaded directly from a room temperature beam via buffer gas cooling. We trap approximately 1 * 10^11 14^N atoms at a peak density of 5 * 10^11 cm^-3 at 550 mK. The 12 +5/-3 s 1/e lifetime of atomic nitrogen in the trap is limited by elastic collisions with the helium buffer gas. Cotrapping of 14^N and 14^NH is accomplished, with 10^8 NH trapped molecules at a peak density of 10^8 cm^-3. We observe no spin relaxation of nitrogen in collisions with helium.
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