[en] The collisional excitation transfer for the processes Rb^*(5P_3/2) + K(4S_1/2) → Rb(5S_1/2) + K^*(4P_J), J = 1/2, 3/2, was investigated using two-photon laser excitation techniques 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(4P_J) → K(7S_1/2) excitation channel. (orig./WL)