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

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.