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Resonance Raman enhancement for adenine and guanine residues
Author(s) -
Majoube M.,
Millié Ph.,
Lagant P.,
Vergoten G.
Publication year - 1994
Publication title -
journal of raman spectroscopy
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.748
H-Index - 110
eISSN - 1097-4555
pISSN - 0377-0486
DOI - 10.1002/jrs.1250251008
Subject(s) - raman spectroscopy , resonance (particle physics) , chemistry , guanine , excited state , excitation , resonance raman spectroscopy , ab initio , vibronic coupling , delocalized electron , analytical chemistry (journal) , molecular physics , nuclear magnetic resonance , atomic physics , optics , nucleotide , biochemistry , physics , gene , electrical engineering , organic chemistry , chromatography , engineering
Reliable assignments for normal modes of adenine, 9‐methyladenine, guanine and 9‐methylguanine were obtained from ab initio 3–21G force fields and optimized geometries. In addition, relative itensities were calculated at resonance with the excited states corresponding to the lowest energy π–π * orbital excitations from the change in bond order and the L −1 matrix. Wavenumbers and relative intensities for resonance Raman active modes Were compared with those previously observed for resonance Raman enhanced bands of AMP and GMP in aqueous solutions obtained with excitation near the absorption band at 260 nm and below. There is satisfactory agreement between observed and calculated relative intensities for the guanine residue. In particular, the large increase in intensity observed for the CO stretching band at 1670 cm −1 with excitation below 220 nm is correctly reproduced. On the other hand, there is less agreement for the adenine residue where the distribution of intensity at resonance according to the A term of the resonance Raman theory is probably altered by the presence of vibronic coupling.