The absolute value of the quantum yield of the fluorescence of the 1B3u 0–0 state of pyrazine as a function of the rotational quantum numbers

In this paper we fit low‐resolution spectra of pyrazine by assuming Coriolis coupling between S1 and {S0}. Evidence for Coriolis coupling is particularly obvious in the rovibronic spectra of pyrazine‐d3h1 of which we give high resolution examples. For the lowest rotational temperature we noticed a non‐Boltzmann distribution of the J‘=0 ground state, which is probably caused by a bottleneck for ΔJ‘=−2 transitions. Using the lifetimes of molecular eigenstates belonging to P(1) we can calculate the absolute quantum yield of the vibrationless and rotationless 1B3u state. Using this number and the obtained interstate Coriolis coupling rate constants we calculate the variation of the absolute quantum yield across the rotational contour. For low J we get satisfactory agreement with experiments, but for high J our calculations drop off too fast with J. We explain this by the fact that at high J values triplet decay becomes dominant because of K scrambling in the triplet manifold