LASER-INDUCED PHOTODISSOCIATION OF S-TETRAZINE PROBED BY PHOTOELECTRON-SPECTROSCOPY WITH SYNCHROTRON RADIATION

We have combined a cw visible laser with synchrotron radiation, respectively, to photodissociate the s-tetrazine molecule and to probe, with an electron analyzer, the vibrational energy of the nascent fragments. No fragments other than N2 and HCN were detected on the time scale of our experiment. We find that 5.4% +/- 0.5% of the nitrogen fragment departs with one quantum of vibration and at least 26% of each HCN fragment is vibrationally excited, mainly in the bending mode (n = 1 to 6) and probably to a very small extent in the C-N stretching mode (n = 1). These data are fully consistent with a pure three body fragmentation mechanism governed by the geometry of the transition state as calculated by Scheiner et al., J. Am. Chem. Soc. 108, 8160 (1986).