Knowledge Bank

Upper-state phosphorescence is observed, and analyzed in p-ch1oro-benualdehyde at 4.2$\mathrm{<mrow\; data-mjx-texclass="ORD">\circ </mrow>}K$ in methy1cyclohexane matrix. The vibrationa1 analysis indicates Jahn-Teller distortion of the emitting states which are separated by only $46cm-1$ When the state-separation is increased, by environmental changes, the spectra undergo dramatic vibrationa1 changes due to the weakening of vibronic interaction Phosphorescence spectra of other benza1dehydes will be analyzed and the origin of upper-state phosphorescence in these molecules discussed.