Decoupling structural molecular dynamics from excited state lifetimes using few-femtosecond ultraviolet resonant dispersive waves
Abstract
Abstract Optical sources exploiting resonant dispersive wave (RDW) emission are set to revolutionize ultrafast science. We demonstrate this approach by investigating excited state dynamics in morpholine using time-resolved photoelectron imaging. Excitation at 250 nm was achieved via RDW emission inside a helium-filled capillary fibre which, when combined with a short 800 nm probe, realized an instrument response of just 11 ± 2 fs. Two pathways initiate N–H bond fission: an extremely fast (<10 fs) process and a frustrated mechanism (380 fs) with hindered electronic ground state access. Photoelectron angular distributions also indicate average molecular geometry evolving on an intermediate (~100 fs) timescale. This clean distinction between population lifetimes and structural dynamics is enabled by the excellent temporal resolution inherent in RDW-based sources. Electronic structure and nonadiabatic surface hopping calculations support our data interpretation, and the synergy between experiment and theory is vital for developing a complete mechanistic picture.
Article Details
Authors (11)
Sebastian L. Jackson
Andrew W. Prentice
School of Engineering and Physical Sciences, Heriot-Watt University 2 , Edinburgh EH14 4AS,
Lauren Bertram
Physical and Theoretical Chemistry Laboratory, Department of Chemistry, University of Oxford 3 , South Parks Road, Oxford,
Lewis Hutton
Physical and Theoretical Chemistry Laboratory, Department of Chemistry, University of Oxford 16 , Oxford OX1 3QZ,
Nikoleta Kotsina
Christian Brahms
Chris Sparling
John C. Travers
Adam Kirrander
Physical and Theoretical Chemistry Laboratory, Department of Chemistry, University of Oxford 16 , Oxford OX1 3QZ,
Martin J. Paterson
Institute of Chemical Sciences, School of Engineering and Physical Sciences, Heriot-Watt University , Edinburgh EH14 4AS,
Dave Townsend