Laser- and collision-induced fluorescence from Rydberg state of Li2

Experimental Study of the NaK 3(1)Pi State

We report the results of an optical-optical double resonance experiment to determine the NaK 3(1)Pi state potential energy curve. In the first step, a narrow band cw dye laser (PUMP) is tuned to line center of a particular 2(A)1Sigma+(v', J') <-- 1(X)1Sigma+(v", J") transition, and its frequency is then fixed. A second narrowband tunable cw Ti:Sapphirelaser (PROBE) is then scanned, while 3(1)Pi --> 1(X)1Sigma+ violet fluorescence is monitored. The Doppler-free signals accurately map the 3(1)Pi(v, J) ro-vibrational energy levels. These energy levels are then fit to a Dunham expansion to provide a set of molecular constants. The Dunham constants, in turn, are used to construct an RKR potential curve. Resolved 3(1)Pi(v, J) --> 1(X)1Sigma+(v", J") fluorescence scans are also recorded with both PUMP and PROBE laser frequencies fixed. Comparison between observed and calculated Franck-Condon factors is used to determine the absolute vibrational numbering of the 3(1)Pi state levels and to determine the variation of the 3(1)Pi --> 1(X)1Sigma+ transitiondipole moment with internuclear separation. The recent theoretical calculation of the NaK 3(1)Pi state potential reported by Magnier and Millié (1996, Phys. Rev. A 54, 204) is in excellent agreement with the present experimental RKR curve. Copyright 1999 Academic Press.

Precise Molecular Constants for the 6Li2 A1Sigma+u-X1Sigma+g System by Sub-Doppler Polarization Spectroscopy

We report here new and more accurate molecular constants from sub-Doppler polarization spectroscopy of the A1Sigma+u-X1Sigma+g system of 6Li2 using single mode cw dye lasers. These new constants cover the range of vibrational levels from v" = 0-8 in the ground state and v' = 0-24 in the excited state. New molecular constants and RKR potential energy curves for the A1Sigma+u and X1Sigma+g states are given. The Te value for the A1Sigma+u state is 14068.043(34) cm-1. The analysis indicates that there is a noticeable breakdown of the Born-Oppenheimer approximation for the 6Li2 and 7Li2 isotopomers. Copyright 1998 Academic Press.

STATE-RESOLVED COLLISION-INDUCED ELECTRONIC TRANSITIONS

▪ Abstract  Laser and molecular beam techniques have enabled researchers to determine the rovibrational levels populated in collision-induced electronic transitions from specified initial levels of several diatomic molecules. As exemplified by the N2+– and CN–rare-gas systems, such measurements, in combination with theoretical calculations of cross sections for these state-to-state collisional processes, provide a means to understand in detail the dynamics of these electronic quenching and energy transfer processes. The present article reviews state-to-state studies of collision-induced electronic transitions. The various collision systems studied provide examples of both perturbation-assisted “gateways” between the initial and final electronic states and perturbation-independent transitions enabled by nonadiabatic mixing induced by the collision partner.