Hyper-Raman spectroscopy
Unique information is brought from vibrational spectroscopy. IR and Raman spectroscopy has been employed for the measurement of molecular vibration and for the structural chemistry. Hyper-Raman (HR) spectroscopy is known as the third method of the vibrational spectroscopy. Due to difference in the selection rule, the spectral pattern of the HR spectrum is different from the IR and Raman spectra. That is, the HR spectroscopy provides a new tool for the structural analysis.

Application to Biomolecules: deoxynucleotides [1,2]
It is of fundamental importance to understand the spectral features of the deoxynucleotides, since they are the building block of DNA. We have applied the HR spectroscopy to dAMP, dTMP, dGMP, and dCMP.
Because the deoxynucleotides have the absorption band near 266 nm, the 532 nm-excitation beams satisfies the requirement of the resonance effect (i.e., the resonance HR (RHR) spectroscopy). The RHR spectrum of dTMP excellently agrees with its UV resonance Raman (UVRR) spectrum excited at 266 nm. The agreement is explained in terms of the A-term process formulated by Ziegler (RHR) and Albrecht (Raman) under the condition of the resonance to single intermediate state. The RHR spectra of the other deoxynucleotides are also analyzed.
[1] C.N.Yu, H.Hiramatsu, J. Chin. Chem. Soc. 2022, 69, 60-65.
[2] C.N.Yu, H.Hiramatsu, J. Phys. Chem. B, accepted (2022).