Temperature dependence of the emission spectra of p-benzoquinone in a p-dichlorobenzene matrix

► Emission spectrum of p-benzoquinone was measured in p-dichlorobenzene at various temperatures. ► T1-, T2-phosphorescence and S1-fluorescence were observed successively with increasing temperature. ► S1-T2 and T2-T1 energy separations have been determined spectroscopically. ► T1 and T2 states have been assigned to be B1g and Au, respectively.