Resonance Raman spectra of n-pi* singlet-triplet transition of p-benzoquinone at low concentrations.
A weak visible absorption spectrum of p-benzoquinone (p-BQ) in CS2 due to n-pi* singlet-triplet transition was measured. Using the resonance Raman (RR) effect in liquid-core optical fiber (LCOF), we have obtained the 514.5 nm excited RR spectra of p-benzoquinone near 1445 cm(-1) and have demonstrated that the new characteristic RR band is attributed to the symmetric C=O stretch (nu(C=O)) of n-pi* singlet-triplet transition of p-BQ. The effect of solution concentration on the RR band was investigated at very low concentrations. The RR peak spreads toward short wavelength side with decreasing solution concentration ranging from 10(-7) to 10(-11) mol L(-1), whereas the blue-shift isn't obvious when the concentration is, at single molecule level, lower than 10(-11) mol L(-1). Our result is useful for single molecule detection to some extent.
Yin
Jian-Hua
JH
Key Laboratory of Coherent Light, Atomic and Molecular Spectroscopy, College of physics, Jilin University, Educational Ministry of China, Changchun 130023, PR China.
Li
Zuo-Wei
ZW
D016227:Benzoquinones / Q000737:chemistry*; D006860:Hydrogen Bonding; D010084:Oxidation-Reduction; D013059:Spectrum Analysis, Raman
D016227:Benzoquinones; C004532:quinone