Optical absorption and 2 photon resonant multiphoton ionization (REMPI) and photoacoustic (PA) spectroscopic measurements on static samples and REMPI measurements on jet cooled samples of norbornadiene have been carried out to both interpret the spectrum of this molecule and to compare the results obtained by the different techniques. All three methods detected the structured 3s Rydberg <-X transition of norbornadiene but only the optical measurement could detect either of two diffuse valence transitions in this molecule. Comparisons of the REMPI and PA results indicated that the failure of these techniques to detect valence transitions is probably due to their small 2 photon cross sections. The 3s Rydberg <- X transition of norbornadiene was also analyzed. Polarization-selected, 2- and 3-photon REMPI measurements were carried out on the 3p Rydberg <- X transitions of acetone. The results were interpreted to indicate a significant reduction in the CCC angle deformation force constant on excitation and a coupling of one of these Rydberg states to the Pi-Pi* excited state of acetone. From the latter, the Pi-Pi* excited state was estimated to lie approximately 8 eV above the ground state of the molecule.
