Enhanced positive secondary ion emission from substituted polynuclear aromatic hydrocarbon/sulfuric acid solutions

Abstract

AbstractSecondary ion mass spectra of singly substituted aromatic hydrocarbon/H2SO4 solutions showed intense aromatic molecular ion and protonated aromatic molecule peaks characteristic of dissolved aromatic compounds from a number of aromatic compound classes, including acids, aldehydes, ketones, nitriles and nitrogen heterocycles. The presence of simultaneously abundant peaks for molecular ions and protonated molecules in secondary ion mass spectra of each aromatic compound/sulfuric acid solution is consistent with known or expected gas‐phase proton transfer chemistry. The ratio of intensities, M+˙:[M + H]+, appears to be determined by sulfuric acid solution chemistry of the compound. Spectra obtained from 1–2 μl samples were relatively free from chemical noise and persisted for up to 20 min. Detection limits for some substituted aromatic compounds are estimated to be 10−12.