Preliminary experiments carried out the previous year suggest that 1,1,4,4- tetramethyl butadiene emits light at two different wavelengths when excited in the spectral region of the pi-pi* absorption. The excitation spectrum for each emission region is the same, but the excitation spectrum differs from the directly measured absorption spectrum. This is the first diene that has been observed to emit. To characterize (1) the symmetry of, (2) the lifetime of and (3) the wavelength of the emitting state two different types of experiments were either implemented or initiated. The 2 photon resonant multiphoton (RMPI) ionization spectrum was measured over the region of pi-pi* absorption and the adjacent 3p-Rydberg transition. The molecule was observed not to have a strict center of symmetry. The RMPI signal was observed not to correspond to the absorption spectrum. The latter suggests that two different states with significantly different physical properties are contained within the nominal pi-pi* absorption envelope. Instrumentation for time resolved emission measurements is being developed to enable the two emission wavelength regions to be identified, but these measurements have insufficiently progressed to be reported at this time.
