Vibronic progressions in the phosphorescence spectrum of highly dispersed vanadium oxide on silica support, V2O5/SiO2, measured by Hazenkamp and Blasse [18] is simulated. The irregular peak spacing is revealed to be evidence of the existence of a few active vibrational modes coupled with the electronic excited T-1 state, which is assigned to the active state as a photocatalyst. Among the active modes, the Jahn-Teller mode is responsible for the photocatalytic reactivity. (C) 2013 Elsevier B. V. All rights reserved.