Electric Fields Influence Intramolecular Vibrational Energy Relaxation and Line Widths

Area of Science:

• Chemical dynamics
• Molecular spectroscopy
• Quantum chemistry

Background:

• Intramolecular vibrational energy relaxation (IVR) is a key process in chemical dynamics.
• Vibrational line widths provide insights into molecular interactions and dynamics.
• External electric fields can influence molecular properties and behavior.

Purpose of the Study:

• To investigate the effect of external electric fields on IVR and vibrational line widths.
• To understand the mechanisms by which electric fields alter IVR channels.
• To explain experimental observations of decreased vibrational line width in benzonitrile under an electric field.

Main Methods:

• Theoretical modeling of molecular dynamics under external electric fields.
• Analysis of anharmonic couplings and frequency detunings between vibrational modes.
• Identification and characterization of IVR pathways influenced by electric fields.

Main Results:

• External electric fields significantly affect IVR and vibrational line widths by modifying anharmonic couplings and frequency detunings.
• Three distinct IVR channels influenced by electric fields were identified in benzonitrile.
• The dominant channel involves electric field-induced changes in frequency detuning, while others are due to altered anharmonic couplings.
• The combined effect of these channels explains the experimentally observed reduction in vibrational line width with increasing electric field.

Conclusions:

• External electric fields provide a means to control IVR and vibrational line widths.
• The study elucidates the specific mechanisms through which electric fields modulate IVR pathways.
• Results offer a more comprehensive interpretation of vibrational Stark probe line width data and suggest field-controlled chemical dynamics.