Dissociative photoionization of L-menthone: An experimental and theoretical study

Research highlights: → Firstly, the dissociative photoionization mechanism of L-menthone has been investigated for the first time with photoionization mass spectrometry using synchrotron radiation. The IE of L-menthone and the appearance energies (AE) of its major fragment ions are not reported up to now. This work involving experimental techniques and theory methods apply to an important molecule: the menthone. → Secondly, as well as the other biogenic volatile organic compounds (BVOCs) which emitted into the atmosphere by plants, menthone is also implicated in aerosol and smog formation and may play a role in the photophysics and photochemistry of the atmosphere. So we make a dissociative photoionization study of L-menthone in the photon energy region of ∼8-15.5 eV. Comparatively, the experimental dissociation energies are in fair agreement with the theoretical values of some possible photodissociation channels. → Finally, thermochemical data, coupled with the observed AEs, are useful in clarifying dissociative photoionization pathways. This work may be helpful to investigate the characterization of secondary organic aerosol (SOA) formed during the photodecomposition and photooxidation of the biogenic volatile organic compounds (BVOCs) menthone in smoke chamber. -- Abstract: The dissociative photoionization mechanism of L-menthone has been investigated with photoionization mass spectrometry using synchrotron radiation. The adiabatic ionization energy (IE) of L-menthone and the appearance energies (AE) of its major fragment ions C9H15O+, C9H17+, C8H16+, C7H11O+, C6H10O+, C6H9O+, C5H8O+, C5H10+, C4H6O+, C5H9+, C4H8+, C4H7+, C3H7+, C3H6+, C2H2O+, and CH3+ are determined with their photoionization efficiency (PIE) spectra in the photon energy region of ∼8-15.5 eV. Breakdown diagrams identifying the major products are presented. Dissociative photoionization channels for formation of these fragment ions are proposed based on comparison of determined experimental appearance energies and energies predicted with the DFT calculations. According to our results, the experimental dissociation energies are in fair agreement with the theoretical values of the possible photodissociation channels of C10H18O.