Infrared Laser Excitation Controlled Reaction Acceleration in the Electronic Ground State

Abstract

Propelling a ground state reaction by mode-specific vibrational excitation via infrared (IR) light offers a novel route to carry out ground state chemistry. Here, we describe the acceleration of a bimolecular alcoholysis reaction as a paradigm for IR light-driven ground state reactions. Instead of resorting to coherent control, IR light is used for direct or indirect vibrational excitation of the reaction coordinate (RC) overcoming the activation energy and promoting the ground state reaction with negligible heating of the sample. Thus, knowledge of the RC is crucial to pick the reaction accelerating vibrations. Alternatively, upon mapping the reaction accelerating vibrations an image of the RC can be reconstructed. We discuss the concept of RCs and examine strategies to use vibrational energy relaxation pathways to single out vibrations belonging to the RC. The influence of the solvent interaction and limitations due to conformational heterogeneity are considered. We provide an application example generating microstructures of polymers and address the use for chemical synthesis in general.

Bond-Breaking/Bond-Forming Reactions by Vibrational Excitation: Infrared-Induced Bidirectional Tautomerization of Matrix-Isolated Thiotropolone

“…5,9 Alternatively, if a dominant (nonstatistical) IVR pathway exists due to the coupling between an excited vibrational mode and a reaction coordinate, this might be exploited to induce a desired chemical transformation in an elegant and selective way. 3,10 One remarkable example illustrating this possibility is the vibrationally induced unimolecular reaction of the jet-cooled Criegee intermediate syn-CH 3 CHOO, reported by Lester and co-workers 11−14 The authors demonstrated that excitation of CH stretching overtones or combination modes induces a 1,4-H shift from the methyl group to the terminal oxygen and activates decomposition of the molecule (Scheme 1). 11 Nevertheless, the application of this strategy to induce and control organic reactions remains scarcely explored.…”

“…Selective energy deposition in a chosen vibrational mode of a given molecular species is a promising way to achieve exquisite control of chemical reactions. − This approach contrasts with conventional heating, in which energy is nonselectively deposited in all molecules of the considered system. The dream of tuning light at a vibrational frequency of a particular bond and inducing a chemical reaction only at that site is extremely challenging, even using femtosecond pulses under low-pressure gas-phase conditions .…”

Energy-efficient pathway for selectively exciting solute molecules to high vibrational states via solvent vibration-polariton pumping

“…Up to now, there have been only a few observations of selective IR photochemistry (i.e. reactions where an IR pump promotes selective reactions beyond a simple heating effect) [3,4]. Recent experiments by Weinstein et al [5] have concluded that, with proper IR pumping, one can achieve modest increases in electron transfer rates after applying a subsequent UV pulse.…”

Direct Optimal Control Approach to Laser-Driven Quantum Particle Dynamics

“…Originally developed by Rabitz et al [6,7] and Kosloff et al [8], numerous methodological extensions have been developed over the years (for reviews, see e.g., [9][10][11][12]). In terms of practical realizations of chemical reaction control, the feedback strategy [1,13,14] as well as straightforward resonant excitation schemes [15][16][17] have been most successful.…”