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arXiv · 2510.25365

Terahertz Time-Domain Spectroscopy and Density Functional Theory Analysis of Low-Frequency Vibrational Modes of a Benzoxazolium-Coumarin Donor-pi-Acceptor Chromophore

Sidhanta Sahu·Phalguna Krishna Das Vana·Anupama Chauhan·Poulami Ghosh·Vijay Sai Krishna Cheerala·Sanyam·C. N. Sundaresan·N. Kamaraju
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Abstract

To elucidate low-frequency vibrational modes, we investigate a benzoxazolium--coumarin (BCO+) donor-pi-acceptor derivative using transmission terahertz time-domain spectroscopy (THz-TDS). The retrieved complex refractive index reveals distinct modes at 0.62, 0.85, 1.30, 1.81, and 2.07 THz. Gas-phase density functional theory (DFT) agrees well with these features and enables assignment of specific intramolecular motions. Together, THz-TDS and DFT identify the characteristic low-frequency modes of BCO+ and suggest their connection to intramolecular charge transfer-relevant nuclear motions, highlighting that THz-TDS can serve as a sensitive probe of vibrational signatures in donor-pi-acceptor systems.

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Sidhanta Sahu, Phalguna Krishna Das Vana, Anupama Chauhan, Poulami Ghosh, Vijay Sai Krishna Cheerala, Sanyam, C. N. Sundaresan, N. Kamaraju. 2025-10-29. Terahertz Time-Domain Spectroscopy and Density Functional Theory Analysis of Low-Frequency Vibrational Modes of a Benzoxazolium-Coumarin Donor-pi-Acceptor Chromophore. https://arxiv.org/abs/2510.25365

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