ELECTRON-EMISSION AND DESORPTION FROM FROZEN GASES UNDER FAST (MEV) ION-BOMBARDMENT

First results of the adsorbate-thickness dependence of electron yields obtained with thin copper foils covered with solid CO2 are presented. Absolute values of the CO2 coverage were determined by Rutherford forward scattering. The erosion of frozen CO2 by transmission of protons (1 MeV) was observed for the first time. The obtained CO2 thickness was related to the yield of convoy electrons (E(e) almost-equal-to 540 eV) being emitted along the beam direction (theta = 0-degrees) with a velocity nu(e) equal to the projectile velocity nu(p) and to the intensity of low energy "true" secondary electrons (E(e) < 50 eV). Surprisingly, the adsorbate thickness dependence of both electron yields is not affected by different electron transport lenghts lambda(E(e)). Our alternative interpretation is based on nonuniform erosion, which generates a modification of the bombarded and the contaminated target area with increasing irradition time.