Vibronic assignments and vibronic coupling in the 1E′′ state of s y m-triazine by two photon spectroscopy

Publisher Website
Google Scholar
Abstract
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 ν6′ progression. These observations include: 610(A″1) ∼0 cm−1, 610 (E″) ∼227 cm−1, 620 (E″) ∼556 cm−1, 630 (E″) ∼693 cm−1, and possibly 640 (E″) [81o (E″) or 1910 (E″)] ∼836 cm−1 above the 1E″, origin. The one photon observed 610 (A2″) and 620 (A2″) bands at 677 and 1176 cm−1 respectively, fit in well with these assignments. These observations are strongly supported by a Jahn–Teller calculation which predicts: little coupling betwwen the A2″ 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.

This publication has 30 references indexed in Scilit: