Electron emission and desorption from frozen gases under fast (MeV) ion bombardment

Abstract First results of the adsorbate-thickness dependence of electron yields obtained with thin copper foils covered with solid CO 2 are presented. Absolute values of the CO 2 coverage were determined by Rutherford forward scattering. The erosion of frozen CO 2 by transmission of protons (1 MeV) was observed for the first time. The obtained CO 2 thickness was related to the yield of convoy electrons ( E e ≈ 540 eV) being emitted along the beam direction ( Θ = 0°) with a velocity ν c equal to the projectile velocity ν p and to the intensity of low energy “true” secondary electrons ( E e λ ( E e ). Our alternative interpretation is based on nonuniform erosion, which generates a modificaton of the bombarded and the contaminated target area with increasing irradiation time.