Abstract：The visible absorption spectra of p-benzoquinone (PBQ) in CS2 were measured, and a weak absorption band around 507 nm attributed to n-π* singlet-triplet transition was demonstrated. Using the resonance Raman effect excited in liquid-core optical fiber which can enhance Raman intensity by 6-9 orders of magnitude, the authors obtained the 514.5 nm excited resonance Raman (RR) spectra of PBQ at 1 439 cm-1 in the concentration range from 10-3 to 10-6 mol·L-1. The new characteristic RR band is attributed to the symmetric CO stretch (νCO) of n-π* singlet-triplet transition of PBQ. The resonance Raman shift is blue-shifted with decreasing concentration. The results of this paper are helpful for understanding the relationship between the electric structure and the photophysical properties of PBQ, and for obtaining more abundant structural information of molecules.
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