Subpicosecond processes in nucleic acids bases monitored by Raman spectroscopy

In this work the Raman total half band widths of five nucleic acids nitrogenous bases (adenine, guanine, cytosine, thymine and uracil) have been measured, respectively.

Raman scattering can be used to study the fast subpicosecond dynamics of purinic and pyrimidinic nucleic acids bases in solid state. The dependencies of the total half band widths and of the corresponding global relaxation times, on atomic groups and on the type of free nucleic acids bases, are reported.

In our study, the full widths at half-maximum (FWHMs) for the Raman bands of nucleic acids bases, are typically in the wavenumber range from 9.5 to 22 cm⁻¹. Besides, it can be observed that molecular relaxation processes studied in this work, have a global relaxation time value smaller than 1.06 ps and larger than 0.46 ps.

We have found that the band centered at 941 cm⁻¹ of adenine, the profiles near 1232 cm⁻¹, 1678 cm⁻¹, in the case of guanine, the band around 1116 cm⁻¹ attributed to cytosine, the profiles at 1490, 1673 cm⁻¹ attributed to thymine and several Raman bands corresponding to atomic groups in uracil, respectively, are suitable for further studying the dynamical behavior of molecular fragments in nucleic acids bases.