BEYOND MGR - WAVE-PACKET SQUEEZING

The MGR scenario for Electron-Stimulated Desorption proved to be a ver y fruitful model allowing for theoretical interpretation for a broader class of desorption experiments than originally intended. New experim ental tools and techniques require, however, considering alternative s cenarios to interpret the results. Depending on one's preferences, alm ost all of them can either be considered as genuinely new ones or mere ly an MGR in disguise. I am concentrating here on one such scenario, t he Wave Packet Squeezing model, which was invoked recently to account for the experimental features of ESD of physisorbed atoms from metal s urfaces which the Antoniewicz version of the MGR model cannot deal wit h. Time evolution of the wave packet shape rather than that of its pos ition is seen as the most important feature of the desorption process. It is shown that wave packet squeezing in three dimensions may affect drastically the angular as well as the kinetic energy distributions o f particles desorbing in the direction of the surface normal. Several examples of the wave packet spreading/squeezing scenarios, invoked rec ently by other researchers in the context of rotational distributions of desorbing molecules, are also briefly discussed.