Raman and Surface-Enhanced Raman Spectroscopy of Purine Derivatives

The thesis proves an experimental basis for the featured characteristics of adenine and demonstrates the conditions for excitation wavelength dependency on vibrational modes to observe the spectral contributions by relative intensities. Purine derivative, adenine is the most ubiquitous of all the heterocyclic compounds in nature. Raman spectroscopy, which provides the signature of molecular vibrational fingerprints, is an emergent method to help identify a substrate and to examine compounds in nature. Raman spectra of adenine powder were acquired using excitation sources with 532 nm, 633 nm and 785 nm wavelengths. In comparison to the most distinct peak at 720 cm-1, the intensities of the peaks between 1200 cm-1 and 1500 cm-1exhibited a characteristic increase with decreasing excitation wavelength. This trend can be reproduced by different density functional theory (DFT) calculations for the adenine molecule. We showed that the above trend can also be seen in the aqueous solution of adenine. If the assumption of any peak intensity dependence on attenuated power , the Raman spectra remains to have no evidence on the spectra but could illustrate that well agreement of peak assignments despite power changes. The gained knowledge of spectroscopy potential and the characteristic of the compound, we tried to monitor a reaction in situ with the help of enormous enhancement, surface-enhanced Raman scattering (SERS). The most prominent peak of the compound, the adenine at 733 cm-1 can be exploited as signatures to identify the reaction in situ and the reaction product, hypoxanthine can also have splited prominent peak at 721 cm-1 and 740 cm-1 respectively. Despite the prominent peaks, the Raman spectrum provides distinctive peaks to integrate its area to function the reaction changes.