THE COLLISION CROSS-SECTIONS FOR EXCITATION-ENERGY TRANSFER IN RB-ASTERISK(5P(3/2))+K(4S(1/2)) -] RB(5S(1/2))+K-ASTERISK(4P(J)) PROCESSES

The collisional excitation transfer for the processes Rb*(5P3/2) + K(4S1/2) --> Rb(5 S1/2) + K*(4 P(J)), J = 1/2, 3/2, was investigated using two-photon laser excitation technique with a thermionic heat-pipe diode as a detector. The population densities of the K 4P(J) levels induced by collisions with excited Rb atoms as well as those produced by direct laser excitation of the potassium atoms were probed through the measurement of the thermionic signals generated due to the ionization of the potassium atoms emerging from the K (4 P(J)) --> K (7 S1/2) excitation channel. The measurements of the thermionic signals in addition to the spectroscopic determination of the potassium number density yield the following values for the excitation transfer cross sections: sigma1(Rb 5 P3/2 --> K 4 P1/2)=8 angstrom2 and sigma2(Rb 5 P3/2 --> K 4 P3/2) = 11 angstrom. The accuracy of the presented results is -/+ 15%. The obtained results are compared to those for the opposite processes K* (4 P(J)) + Rb(5 S1/2) --> K(4 S1/2) + Rb*(5 P3/2).