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.