Abstract: | Vacuum ultraviolet (VUV) dissociative photoionization of isoprene in the energy region 8.5–18 eV was investigated with photoionization mass spectroscopy (PIMS) using synchrotron radiation (SR). The ionization energy (IE) of isoprene as well as the appearance energies (AEs) of its fragment ions C5H7+, C5H5+, C4H5+, C3H6+, C3H5+, C3H4+, C3H3+ and C2H3+ were determined with photoionization efficiency (PIE) curves. The dissociation energies of some possible dissociation channels to produce those fragment ions were also determined experimentally. The total energies of C5H8 and its main fragments were calculated using the Gaussian 03 program and the Gaussian‐2 method. The IE of C5H8, the AEs for its fragment ions, and the dissociation energies to produce them were predicted using the high‐accuracy energy model. According to our results, the experimental dissociation energies were in reasonable agreement with the calculated values of the proposed photodissociation channels of C5H8. Copyright © 2009 John Wiley & Sons, Ltd. |