1,2-Divinylcyclopentene (DVCP-d(0)) and its terminally tetradeuterated isotopomer (DVCP-d(4)) are studied as models for (Z)-1,3,5-hexatriene locked with respect to torsion around the central C-C bond. Preresonance Raman (DVCP-d(0)) and resonance Raman (DVCP-d(4)) spectra of the ground state and time-resolved resonance Raman and absorption spectra and kinetics of the lowest excited triplet state of both isotopomers are reported. The observed spectra are compared with results from theoretical calculations. Optimized geometrics, vibrational frequencies, and resonance Raman intensities are calculated for S-0 and T-1 by both ab initio and semiempirical (QCFF/PI) methods. The triplet lifetime of DVCP-d(0) is found to be 3.4 mu s, a factor of 17 longer than for (Z)-1,3,5-hexatriene, demonstrating the importance of torsional motion around the central C-C bond in the deactivation of 1,3,5-hexatriene. Terminal deuteration prolongs the triplet lifetime even further, which seems to indicate that deactivation in DVCP occurs through a vibration involving the terminal hydrogen atoms. Furthermore, a comparison of T-1 resonance Raman spectra of different (Z)-1,3,5-hexatrienes leads to the suggestion of the existence of a marker band around 1273 cm(-1) characteristic for the presence of the planar Z conformation of hexatrienes in the T-1 state.