Anharmonic Backbone Vibrations in Ultrafast Processes at the DNA-Water Interface

Area of Science:

• Physical Chemistry
• Biophysics
• Spectroscopy

Background:

• Understanding DNA's structural integrity requires knowledge of its backbone dynamics.
• The interaction between DNA and its aqueous environment influences its stability and function.

Purpose of the Study:

• To investigate the vibrational modes of the DNA backbone.
• To explore their interactions with the surrounding water molecules.
• To elucidate energy transfer and dissipation mechanisms.

Main Methods:

• Utilized two-dimensional (2D) infrared spectroscopy.
• Operated on a femtosecond to picosecond timescale.
• Analyzed spectral lineshapes to probe structural dynamics.

Main Results:

• Determined anharmonic character and delocalization of DNA backbone modes (900-1300 cm(-1)).
• Observed picosecond timescale energy transfer between backbone modes.
• Identified limited structural fluctuations on a 300 fs timescale.
• Found DNA-water interface disorder and hydrogen bonds persist beyond 10 ps.

Conclusions:

• Anharmonic couplings mediate energy transfer and dissipation in the DNA backbone.
• Ultrafast vibrational relaxation and energy dissipation are crucial for hydrated DNA structural integrity.
• Limited structural fluctuations occur on short timescales, while interface disorder is longer-lived.