Can internal conversion be controlled by mode specific vibrational excitation in polyatomic molecules

by Michael Epshtein

at Quantum optics seminar

Thu, 19 Jan 2017, 15:30
Physics building (#54) room 207

Abstract

Non adiabatic dynamics at conical intersections CI extensively affects the photostability of biomolecules by efficiently photoinducing decay routes that dissipate harmful excess ultraviolet energy Since one of the means for controlling the course of dissociation is considered to be selective excitation of vibrational modes containing a considerable component of motion we have chosen to study here the predissociation of the model test molecules methylamine CH3NH2 and its deuterated isotopologues excited to different specific vibrational modes in the electronically excited state The first demonstrated detection of H D photofragments by Doppler free DF ion imaging and velocity resolved action spectra allowed measurement of the entire velocity distributions of the photofragments in each laser pulse and getting insight into the dynamics The fast and slow H D products resulting from N H and N D bond cleavage obtained via two different dissociation pathways showed anomalous distributions for some rovibronic states as indicated by dynamic resonances in the product branching ratio in the internal energies of the CH3NH D photofragments and in the anisotropy parameters of the fast H photofragments These correlated anomalies for predissociation initiated from specific rovibronic states allowed to reach energetic regions on the excited electronic states that led to dynamic predesign and control of the ensuing photoproducts and are not necessarily related to the distinctive pre excited nuclear motions These resonances play an important role in the bifurcation dynamics at the CIs in the different isotopologues and can be foreseen to exist in other photoinitiated processes and to control their outcome

Created on 15-01-2017 by Bar Lev, Yevgeny (ybarlev)
Updaded on 15-01-2017 by Bar Lev, Yevgeny (ybarlev)