Computational Methods for Excited State Time-Resolved Vibrational Spectroscopies

Time-resolved Infrared (IR) and Raman¹ spectroscopies, have become increasingly important in modern chemical, biological, and materials research. This modern focus is primarily due to their capability to study non-equilibrium structural dynamics of ultrafast chemical phenomena.²
A computational approach based on both ab-initio molecular dynamics and transient vibrational analysis is presented to establish a time-dependent density functional theory (TDDFT) based protocol able of describing simultaneously transient IR and Raman active vibrational modes. This work relies on the recent method development for the evaluation of higher-order TDDFT properties and multiresolution time-frequency analysis.³
Excited state photo dynamics of prototypical molecules in gas phase will be used as test cases, showing the evolution of the vibrational signatures upon the excitation.
This protocol is critical to understand how nuclear motions can mediate the photo-dynamics of several photo-active systems.

1. P. Kukura, et al., Annu. Rev. Phys. Chem.; 58, 461 (2007).
2. M. Dantus, et al., J. Chem. Phys.; 87, 2395-2397 (1987).
3. A. Petrone, et al., J. Am. Chem. Soc.; 136, 14866-14874 (2014), and J. Phys. Chem. Lett.; 7, 4501-4508 (2016), and A. Petrone, et al., J. Phys. Chem. A, 121 (20), 3958-3965 (2017).