Analysis of the desorption of clusters of intact amino acid valine molecules induced by energetic monoatomic and cluster ions

The experiments on the desorption of intact valine molecules and (nM + H)+ clusters are analyzed and a ln(Y/Se) − 1/Se scaling is found where Y, and Se are the sputtering yield and the electronic stopping power, respectively. The scaling can be derived with the assumption of a thermal activation mechanism. In the plots the desorption is a uniform process without threshold value of Se, having different activation energies U in various charge states. The desorption of (nM + H)+ clusters proceeds in n steps with varying Coulomb contributions. Irradiation with C10 and C60 ions leads to higher Y, however, the increment is reduced with the increase of Se.