Interaction of ruby laser radiation with thallium vapor

An experimental investigation was made of the interaction of ruby laser radiation with a vapor of thallium atoms. Several atomic lines in the infrared range were observed and investigated for the first time. These lines were due to multiphoton excitation of the thallium atoms. The dependences of the energies of the infrared emission lines on the intensity of the exciting laser radiation indicated that they appeared because of multiphoton ionization of the atoms. Nonresonant stimulated Raman scattering involving electronic transitions between the 6P_1/2 and 6P_3/2 levels in the thallium atom was observed and studied. The polarization of the infrared emission lines and of the Raman lines was investigated as a function of the polarization of the exciting laser radiation. The energy efficiency of infrared conversion was ~10^–5 %.