LASER-INDUCED THERMAL-DESORPTION OF ANILINE FROM SILICA SURFACES

A complete study on the energy partitioning upon laser-induced thermal desorption of aniline from silica surfaces was undertaken. The measurements include characterization of the aniline-quartz adsorption system using temperature-programmed desorption, the extrapolation of quasiequilibrium desorption temperatures to the regime of laser heating rates on the order of 10(9)-10(10) K/s by computational means, measurement of the kinetic energy distributions of desorbing aniline using a pump-probe method, and the determination of internal energies with resonance-enhanced multiphoton ionization spectroscopy. The measurements are compared to calculations of the surface temperature rise and the resulting desorption rates, based on a finite-difference mathematical description of pulsed laser heating. While the surface temperature of laser-heated silica reaches about 600-700 K at the time of desorption, the translational temperature of laser-desorbed aniline was measured to be T-kin=420+/-60 K, T-vib was 360+/-60 K, and T-rot was 350+/-100 K. These results are discussed using different models for laser-induced thermal desorption from surfaces. (C) 1995 American institute of Physics.