Huo, Y.; Cangahuala, M.K.E.; Zamudio-Bayer, V.; Goulart, M.; Kubin, M.; Timm, M.; Lau, J.T.; Issendorff, B.v.; Hoekstra, R.; Faraji, S.; Schlathölter, T.: A comparative laboratory study of soft X-ray-induced ionization and fragmentation of five small PAH cations. The European Physical Journal D 77 (2023), p. 181/1-11
10.1140/epjd/s10053-023-00763-w
Open Access Version
Abstract:
The interaction between polycyclic aromatic hydrocarbon (PAH) radical cations and X-rays predominantly leads to photofragmentation, a process that strongly depends on PAH size and geometry. In our experiments, five prototypical PAHs were exposed to monochromatic soft X-ray photons with energies in the C K-edge regime. As a function of soft X-ray photon energy, photoion yields were obtained by means of time-of-flight mass spectrometry. The resulting near-edge X-ray absorption mass spectra were interpreted using time-dependent density functional theory (TD-DFT) with a short-range corrected functional. We found that the carbon backbone of anthracene+ (C14H+ 10), pyrene+ (C16H+10) and coronene+(C24H+12) can survive soft X-ray absorption, even though mostly intermediate size fragments are formed. In contrast, for hexahydropyrene+ (C16H+ 16) and triphenylene+ (C18H+12) molecular survival is not observed and the fragmentation pattern is dominated by small fragments. For a given excitation energy, molecular survival evidently does not simply correlate with PAH size but strongly depends on other PAH properties.