[Collisional transfer of the Cs(8S) state and excitation of high lying atomic states].

Using selective stepwise excitation of the cesium 8S atomic level in Cs vapor, the collisional transfer and the population of the high-lying atomic states were studied in detail. At cesium densities of 10(16)-10(17) cm(-3), the rate coefficient of excitation collision [i. e., 8S+6S --> 6D+6S] was measured. Measurement of fluorescence intensities as a function of Cs density yields k6D = (2.4 +/- 0.5) x 10(-10) cm3 x s(-1). The 5D state was populated by the 8S --> 7P --> 5D transitions. The energy pooling collisions 5D+5D --> nL+6S (nL = 9D, 11S, 7F) were also studied. The rate coefficients were measured relative to the known rate coefficient of the collision [i. e. 6P+5D --> 6S+7D]. The densities of 6P state were combined with measured fluorescence ratios to determine rate coefficients for EP process. The average values (in unites of 10(-10) cm3 x s(-1)) for nL = 9D, 11S and 7F are 6.4 +/- 3.2, 1.0 +/- 0.5 and 8.4 +/- 4.2, respectively.