Enhanced silver cationization of polycyclic aromatic hydrocarbons containing bay regions in molecular secondary ion mass spectrometry

The relative abundances of silver cationized molecules [Ag + M]+ relative to molecular ions (M+.) in the secondary ion mass spectra of polycyclic aromatic hydrocarbons (PAHs) are directly related to the structures of the PAHs. Compounds containing a ‘bay region’, a concave area at the periphery of the molecule, give [Ag + M]+: M+. abundance ratios which exceed 0.62, whereas this ratio is less than 0.18 for the molecules that lack this structural feature. This allows the recognition of PAHs containing bay regions and the distinction of certain isomeric PAHs, such as phenanthrene and anthracene. Other metals, including copper and nickel, show similar behavior.