Secondary-ion emission of amino acids
- Cite this article as:
- Benninghoven, A., Jaspers, D. & Sichtermann, W. Appl. Phys. (1976) 11: 35. doi:10.1007/BF00895013
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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.
- 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.