Method of investigation of electron impact induced transitions between excited atomic levels

Abstract

Abstract.A method for the measurement of rate constants for inelastic collisions between thermal electrons and excited atoms is presented. The measurements were performed in a mixture of saturated caesium and sodium vapor. Electrons were generated by ionization of caesium vapour by intense resonant dye laser pulses. Pulses of second dye laser, delayed with respect to the first one, excited the sodium atoms to the 3P level. Subsequently Na(3P) atoms were excited to higher levels by collisions with electrons. The fluorescence intensity from these levels served as a measure of the rate constant for these transitions. The method was used to investigate the electron impact induced 3P-4P excitation.

Investigations of Electron Impact Induced Excitations from 3P to Higher Lying Levels of Sodium

“…5). These data were presented also previously [12,13], but without proper correction for the radiation and electron diffusion.…”

“…In the experiment the integration of photons was performed over the finite time interval T =1 μs. As it was shown earlier [13], for T > 4τ the error caused by finite integration time is negligible.…”

“…We neglect collisional population of the nl levels from other states than 3P, because the efficiencies of these transitions are more than one order of magnitude smaller than the k3p-n l(Te ) value [13]. The collisional depopulation of nl levels is also neglected:: -In such conditions the solution of Eq.…”

“…In our previous papers [12,13], where the model of the weak excitation for the radiation diffusion was assumed, the value of this parameter X = 1.37 was used.…”

“…In our two recent papers [12,13] a new method of investigation of electron impact induced transitions between excited atomic levels was presented. Briefly, the experiment was performed in a cell of diameter 2α = 32 mm, containing a mixture of caesium and sodium vapour (Fig.…”