Vibronic Assignments and Vibronic Coupling in the 1E' State of Sym-Triazine by Two Photon Spectroscopy

摘要

Two photon photoacoustically detected spectra are reported for the first excited singlet state 1E' of sym-triazine in the gas phase. The origin has been positively identified as of E' symmetry through contour calculations and hot band observations. The excited state absorption is dominated by a highly irregular progression. Observations are strongly supported by a Jahn Teller calculation which predicts: little coupling between A'2 and E' electronic manifolds; a large quadratic coupling and a small linear coupling in the E' manifold; and a quenched angular momentum in this state. Good agreement is shown to exist between one photon and two photon spectroscopic observations and the calculations.