Department of Physics, Engineering Physics & Astronomy

Queen's University
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Department of Physics, Engineering Physics & Astronomy
Department of Physics, Engineering Physics & Astronomy

CMP Seminar - Spectroscopic Signatures of Nonadiabatic Molecular Dynamics

Michael S. Schuurman

Thursday March 3rd,
10:30 am in Stirling 401
 

Abstract:

The absorption of light by a molecule is the first step in a set of dynamical processes that can yield disparate chemical outcomes, including radiative decay (fluorescence, phosphoresence), nonradiative decay (internal conversion, intersystem crossing) and/or fragmentation. In this talk, I will show how ultrafast nonradiative decay pathways are discovered using ab initio simulation techniques.  Some details of the computational and theoretical approaches for simulating these processes, which invariably involve nonadiabatic transitions between electronic states mediated by the presence of conical intersections, will be presented.  In particular, it will be shown that the 'on-the-fly' determination of the requisite potential energy surfaces using high-level quantum chemistry methods is a useful approach for uncovering precisely which molecular motions engender fast relaxation to the ground state. In addition to the molecular dynamics, the direct simulation of time-resolved observables  (i.e. photoelectron and x-ray absorption spectra) that probe these processes on the inherent femtosecond timescales of vibrational motion will be discussed.  Given the complexity of the resultant spectral signatures of the molecular dynamics, high level simulation will be shown to be an invaluable component in the interpretation of the experimental results.