Reinvestigation of vibronic level dependence of fluorescence quantum yields and radiative and nonradiative lifetimes of p-difluorobenzene in its first excited singlet state (1B2u)

Abstract

The fluorescence quantum yields (Φ_f) of p‐C₆H₄F₂ (¹B_2u) have been measured for a number of vibronic levels at low pressures where ’’isolated’’ molecule condition can be maintained. Our present values obtained by continuous excitation are significantly different than those obtained previously by flash excitation [C. Guttman and S. A. Rice, J. Chem. Phys. 61, 661 (1974)]; we obtain 0.70 vs the previous value of 1.00 for the fluorescence quantum yield of the 0–0 band. On the basis of the new value of Φ_f, a set of revised values of radiative lifetimes (τ_r) and nonradiative lifetimes (τ_nr) of various vibronic levels are obtained.