Emission properties of 1,4-anthraquinone

Emission, excitation and absorption spectra of 1,4-anthraquinone (1,4-AQ) have been measured in a degassed CCl4 fluid solution at different temperatures as well as in a glassy matrix at 77 K. It is shown that 1,4-AQ exhibits weak emission in CCl4 at temperatures near room temperature. Based on the quantitative analysis of the emission yield measured as a function of temperature, the observed emission is attributed to the fluorescence from the S1(n, π∗) state which is in thermodynamic equilibrium with the T1(π, π∗) state.