Atomistic Modeling of IR Action Spectra Under Circularly Polarized Electromagnetic Fields: Toward Action VCD Spectra

The nonlinear response and dissociation propensity of an isolated chiral molecule, camphor, to a circularly polarized infrared laser pulse was simulated by molecular dynamics as a function of the excitation wavelength. The results indicate similarities with linear absorption spectra, but also differences that are ascribable to dynamical anharmonic effects. Comparing the responses between left‐ and right‐circularly polarized pulses in terms of dissociation probabilities, or equivalently between R‐ and S‐camphor to a similarly polarized pulse, we find significant differences for the fingerprint C = O amide mode, with a sensitivity that could be sufficient to possibly enable vibrational circular dichroism as an action technique for probing molecular chirality and absolute conformations in the gas phase. Chirality 27:253–261, 2015 . © 2015 Wiley Periodicals, Inc.