Efficient laser desorption ionization mass spectrometry of polycyclic aromatic hydrocarbons using excitation energy transfer from anthracene

Abstract

Polycyclic aromatic hydrocarbons (PAHs), such as perylene and benzopyrene, doped at amounts on the order of femtomol (∼10−15mol) in anthracene crystals could be detected by laser desorption ionization mass spectrometry. Sensitivity was roughly 103 times higher than that of LDI method in our experimental conditions. It was revealed from the excitation power dependence of the peak intensity of PAHs on the mass spectra that two-photon excitation in one UV pulse was necessary to complete the ionization process. It was also clarified that the number of defect sites that trap excitons generated in anthracene crystals could be reduced by the annealing procedure, by which an efficient energy transfer between anthracene and PAHs became possible.