Infrared double resonance of SiH4 with a tunable diode laser: Two-photon absorptions and rotational relaxation times

Abstract

Time-resolved infrared double resonance experiments have been carried out on silane. A pulsed CO2 laser is used to pump dyad←ground state transitions, and triad←dyad transitions are probed with a tunable diode laser. Two-photon (triad←ground state) signals are observed with the CO2 10P(20), 10P(22), and 10P(28) pump lines. Rotational relaxation rates have been measured for E, F2, and A2 symmetry components of the v4=1, J=13 level of silane in collisions with silane, argon, and methane. The relaxation efficiencies follow the order σrot (F2)>σrot (A2)>σrot (E), which parallels the behavior of pressure-broadening coefficients for infrared absorption lines of methane.