Charge-State Dependence of Desorption of Biomolecules Induced by Fast Heavy Ions

Fast heavy ions in definite charge states have been used to desorb molecular ions. Samples of ergosterol, glycylglycine, and cesium iodide were exposed to 20-MeV oxygen ions in charge states $2^{+}$ to $8^{+}$. For the first time it has been shown that the yields depend strongly on the charge state of the primary ion. Existing models for "sputtering" fail to reproduce the measured yield distributions. The results illustrate that future desorption experiments should be carried out with primary ions in well defined charge states.