Generalized oscillator strength for the first singlet–singlet transition in p-difluorobenzene and the cross section for energy transfer to acetone

Generalized oscillator strengths have been determined for the first singlet–singlet transition (1B2u←1Ag) in p-difluorobenzene. Using this data and similar data for acetone reported earlier [K. N. Klump and E. N. Lassettre, J. Chem. Phys. 68,886(1978)] the cross section for the resonant energy transfer process C6H4F2(1B2u)+acetone(? 1A1) →C6H4F2(1Ag)+acetone(? 1A2) has been calculated from Huo’s model [J. Chem. Phys. 66, 3572 (1977)]. The calculated cross section is 85 Å2. The disagreement with the experimental value of 56±2Å2 [G. L. Loper and E. K. C. Lee, J. Chem. Phys. 63, 264 (1975)] indicates that the Born approximation does not hold as well as in the case of benzene and acetone.