EFFECT OF AN ELECTRIC-FIELD AND COLLISIONS ON THE LASER-INDUCED FLUORESCENCE OF CS MOLECULES

Electric field measurements are reported employing CS molecules as a s ensitive probe. The molecules were produced by a rf discharge in CS2 g as. The A (1) Pi-X (1) Sigma(+) (upsilon' = upsilon '' = 0) band syste m of CS was optically excited by an excimer laser pumped dye laser. Sp ectrally resolved laser-induced fluorescence (LIF) was recorded at var ious strengths of a static electric field in the range of 0 less than or equal to F less than or equal to 6 kV cm(-1). In the theoretical pa rt, intensities of Q- and P-components in the LIF spectrum were calcul ated for two limiting cases: (1) no collisional transfer of the popula tion; (2) complete collision-induced equalization of the populations o f the Zeeman sublevels. Results of the theoretical analysis of the exp erimental data are the following: (1) at relatively weak fields the co llisional transfer dominated over the geometry-related selectivity of the pumping; (2) the weaker the electric field, the more significant w as the role of the collisional transfer; (3) the higher the rotational quantum number of the laser excited state, the broader is the range o f electric fields at which the collisional transfer was the predominan t factor for the populations.