CARBONYL WAGGING, AND RING-PUCKERING POTENTIAL-ENERGY FUNCTIONS OF 3-CYCLOPENTEN-1-ONE IN ITS S-1(N,PI-ASTERISK) ELECTRONIC EXCITED-STATE JET-COOLED FLUORESCENCE EXCITATION SPECTRUM

The jet-cooled fluorescence excitation spectrum of 3-cyclopenten-1-one has been recorded in the 308-330 nm region, and the electronic origin for the S1(n,*) state of A2symmetry was observed at 30 229 cm-1. The observed spectrum consists of more than 80 bands involving primarily 3(carbonyl stretch), 29(carbonyl out-of-plane wagging), and 30(ring puckering). Bands were also assigned to combinations with seven other vibrational modes. The energies for the = 0 to 11 quantum states of 29were measured and used to determine a one-dimensional potential energy function. This function has energy minima at wagging angles of 24 and a barrier to inversion of 939 cm-1. Four bands associated with 30were observed and were used to determine an asymmetric single-minimum one-dimensional ring-puckering potential energy function for the S1(n,*) state. The ring-puckering energy levels in the 29vibrational excited states are little changed from the = 0 state indicating that there is little interaction between the carbonyl wagging and the ring-puckering motions. 1995 American Institute of Physics.

JET-COOLED FLUORESCENCE EXCITATION SPECTRUM, CARBONYL WAGGING, AND RING-PUCKERING POTENTIAL-ENERGY FUNCTIONS OF 3-CYCLOPENTEN-1-ONE IN ITS S-1(N,PI-ASTERISK) ELECTRONIC EXCITED-STATE Academic Article