Pulsed laser induced thermal desorption of CO from copper surfaces

Infrared Laser Photodesorption of Adsorbed Phases

An infrared laser generated from a Nd:YAG laser mixing with a dye laser has been used as a tunable coherent pulsed laser source to photodesorb ammonia from a Cu(100) surface after excitation of the ν3 mode. Timeresolved quadrupole mass spectrometry is sucessfully applied to determine the translational temperatures of the desorbing species from a monolayer coverage on the metal surface. Evidence for desorption induced by vibrational excitation has been obtained and the results are discussed in terms of rapid energy transfer mechanisms.

Focal Points in Mass Spectrometry

Mass spectrometry has advanced with the renaissance of time-of-flight mass analysis, the use of ion traps as analyzers and reactors, the application of tandem mass spectrometers to problems in ionic reaction mechanisms and chemical analysis, and the development of new desorption ionization techniques. These developments have allowed determination of the molecular weight distributions for polymers through the 10,000-dalton range, as well as the molecular weight and partial sequence of biopolymers of similar size. Surfaces can be characterized by use of the mass, energy, and angle distributions of particles ejected by sputtering or by laser-induced desorption. Mass spectrometry has yielded new information on the kinetics of catalytic surface reactions and on the reactivity of metal clusters.