Journal of Physical Chemistry, Vol.98, No.34, 8302-8309, 1994
The 198-225-nm Transition of Norbornadiene
An optical and two-photon resonant multiphoton ionization and photoacoustic spectroscopic investigation of the second transition region of norbornadiene was conducted on static and jet-cooled samples. Transitions to both the 3s Rydberg and the NV2 valence states were observed. The substructure of the 3s Rydberg <-- X transition was deduced to arise from fundamentals, overtones, and combinations of a(1), nu(4), nu(8), nu(10), and nu(12) and overtones and combinations of a(2), nu(18), and nu(20) vibrational modes. Displacements from the ground-state equilibrium geometry were determined for the a(1) modes. The 3s Rydberg state was shown to decay rapidly to the higher energy NV2 valence state via the nu(20) vibrational mode when energetically possible. The diffuse substructure of the NV2 transition was deduced to arise from nu(7), an ethylenic CH bending mode. Comparisons were made between results obtained here and those observed for similar molecules, observed for other states of this molecule, and calculated for these states of norbornadiene.