Past exam of the chemistry course of the year 3 of the natural sciences course of the University of Cambridge / 2021 / Paper 2A / Section B / 22 / b / ii / Solution

Almost every absorbed photon generates a triplet, within the stated kinetic scheme. The branching fraction from the excited singlet isso $k_{\mathrm{ISC}}[S_1]\simeq I_{\mathrm{abs}}$ under steady illumination. This statement concerns the triplet formation yield; it does not mean that the triplet population or the phosphorescence yield is also one. The triplet can subsequently deactivate or be quenched.