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Updated: Nov 7, 2025

Measurement of Ultrafast Vibrational Coherences in Polyatomic Radical Cations with Strong-Field Adiabatic Ionization
Published on: August 6, 2018
Boosting Self-interaction of Molecular Vibrations under Ultrastrong Coupling Condition
Akhila Kadyan1, Anil Shaji2, Jino George1
1Department of Chemical Sciences, Indian Institute of Science Education and Research (IISER) Mohali, Mohali, Punjab 140306, India.
Abstract:
In this letter, we investigated the modification of the oscillator strength of an asymmetric stretching band of CS2 by strong coupling to an infrared cavity photon. This is achieved by placing liquid CS2 in a Fabry-Perot resonator and tuning the cavity mode position to match the molecular vibrational transition. Ultrastrong coupling leads to an increase in the effective oscillator strength of the asymmetric stretching band of CS2. We proved this experimentally by taking the area ratio of the asymmetric stretching and combination bands by selectively coupling the former. A nonlinear increase in the oscillator strength of the asymmetric stretching band is observed upon varying the coupling strength. This is explained by a quantum mechanical model that predicts quadratic behavior under ultrastrong coupling conditions. These findings will set up a new paradigm for understanding chemical reaction modifications by vacuum field coupling.
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