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 measur ements include characterization of the aniline-quartz adsorption syste m using temperature-programmed desorption, the extrapolation of quasie quilibrium desorption temperatures to the regime of laser heating rate s 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 resonan ce-enhanced multiphoton ionization spectroscopy. The measurements are compared to calculations of the surface temperature rise and the resul ting desorption rates, based on a finite-difference mathematical descr iption 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. Th ese results are discussed using different models for laser-induced the rmal desorption from surfaces. (C) 1995 American institute of Physics.