Secondary-ion emission of amino acids
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AbstractSecondary-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:- All investigated amino acids produce high-intensity secondary-ion parent peaks (M+1)+ and (M−1)−.- In addition positive as well as negative fragment ions representative for the different functional groups are emitted with high yields.- For 2.5 keV Ar+-ions the absolute yields for the parent ions and the most important fragment ions are in the range of 0.1; the damage cross section is >10−14 cm2 for all investigated acids. The resulting absolute sensitivities are below 10−6 of one monomolecular layer or <10−12 g.
We infer from these results that static SIMS is an excellent tool for trace detection, structural investigation and surface reaction studies of amino acids.
[1] A. Benninghoven,et al. Secondary ion yields near 1 for some chemical compounds , 1972 .
[2] R. Macfarlane,et al. New approach to the mass spectroscopy of non-volatile compounds. , 1974, Biochemical and biophysical research communications.
[3] A. Benninghoven,et al. Surface investigation of solids by the statical method of secondary ion mass spectroscopy (SIMS) , 1973 .
[4] R. Macfarlane,et al. Californium-252 plasma desorption mass spectroscopy. , 1976, Science.