SPECTROSCOPIC PROBE FOR ENERGY-TRANSFER DURING LASER-DESORPTION FROM SURFACES

Aniline was used as a probe molecule to study energy transfer during l aser-induced thermal desorption from a silica surface. Aniline is a su bstantially larger adsorbate than other molecules whose internal state distributions were previously studied following laser desorption and therefore poses some additional experimental challenges. Using resonan ce-enhanced multiphoton ionization spectroscopy, the internal energy o f laser-desorbed aniline was measured to be T-vib = 360 +/- 60 K and T -rot = 350 +/- 100 K. The results are compared with calculated desorpt ion temperatures of aniline from rapidly heated silica surfaces and ar e discussed in light of different mechanisms for laser-induced thermal desorption of large molecules from surfaces.