Comparative study of [Xe]+ and [Ar]+ bombardment in secondary ion mass spectrometry for bioorganic compounds

Secondary ion mass spectra obtained by Xe]⁺ bombardment are compared with those obtained by Ar]⁺ bombardment. Although Ar]⁺ ions are commonly used as primary ions in secondary ion mass spectrometry for organic compounds, Xe]⁺ ions seem better as primary ions because they give a larger sputtering yield for a metal substrate than Ar]⁺ ions. Cationized molecular intensities of sucrose, raffinose and stachyose, and quasimolecular ion intensities of tuftsin and eledoisin related peptide are investigated using Xe]⁺ and Ar]⁺ bombardments. The observed molecular species are 2–4 times more intense for Xe]⁺ bombardment than for Ar]⁺ bombardment, although the secondary ion mass spectra are almost the same in both cases.