Secondary-ion emission of amino acids

Abstract

Secondary-ion mass spectroscopy (SIMS) is a hydrogen, isotope and compound sensitive analytical technique of extremely high absolute sensitivity. Continuing earlier measurements for carboxylic acids, adsorbed alcohols etc., we have carried out a systematical investigation of secondary-ion emission from metal-supported amino acids, containing various functional groups (e.g., alanine, phenylalanine, cysteine, arginine). In order to avoid damage effects we applied extremely small primary-ion current densities in the 10−9 A·cm−2 range. The main results of our investigations can be summarized as follows: We infer from these results that static SIMS is an excellent tool for trace detection, structural investigation and surface reaction studies of amino acids.