Total molecular yields for fast heavy ion induced desorption of biomolecules

Abstract

The total desorption yield for intact molecules of the amino acid leucine (131 amu) induced by 90MeV 127I 14+ ions has been studied. A collector method was used where the collector samples were analysed using both an amino acid analyzer (via optical absorption) for absolute measurements and Plasma Desorption Mass Spectroscopy for relative measurements of the total number of unfragmented molecules. Results indicate high yields of intact molecules of the order of one thousand which corresponds to a removal of about 1 × 10 5 Å 3 of sample material per incident ion. It has been shown that fast heavy ion induced desorption of leucine is essentially a “neutral ejection” process with the generally studied ionized portion constituting a very small fraction (≈1:10 4).