Anharmonic Vibrational Dynamics of DNA Oligomers

TL;DR

This study combines spectroscopy and computational methods to analyze anharmonic vibrational couplings in DNA oligomers, revealing specific mode interactions that aid in spectral assignment despite water background interference.

Contribution

It introduces a combined experimental and theoretical approach to characterize anharmonic vibrational couplings in DNA, specifically identifying mode interactions relevant for spectral analysis.

Findings

Identified anharmonic coupling between NH₂ bending and CO stretching modes.

Assigned NH₂ fundamental transition at 3215 cm-1.

Demonstrated spectral assignment despite water background.

Abstract

Combining two-color infared pump-probe spectroscopy and anharmonic force field calculations we characterize the anharmonic coupling patterns between fingerprint modes and the hydrogen-bonded symmetric NH$_2$ stretching vibration in adenine-thymine dA$_{20}$-dT$_{20}$ DNA oligomers. Specifically, it is shown that the anharmonic coupling between the NH$_2$ bending and the CO stretching vibration, both absorbing around 1665 cm-1, can be used to assign the NH$_2$ fundamental transition at 3215 cm-1 despite the broad background absorption of water.