APS Logo

Covariance-map imaging: a new dimension for chemical dynamics studies

ORAL · Invited

Abstract

Since velocity-map imaging was first developed over 20 years ago it has revolutionised experimental work in the field of chemical reaction dynamics.  The approach allows the complete scattering distribution for a chosen reaction product to be imaged directly in the gas phase in a single measurement, and has provided fascinating and often quantum-state resolved insights into the mechanisms of a wide variety of photochemical, bimolecular, and surface reactions.

The development of universal ionization methods and ultrafast time-of-flight imaging sensors has ushered in the era of multi-mass velocity-map imaging, in which multiple reaction products can be imaged in a single experiment.  As well as offering a vast reduction in data acquisition time, multi-mass imaging data sets can be analysed using a statistical data processing technique known as covariance mapping to reveal correlations amongst the various detected reaction products.

This talk will provide an introduction to covariance mapping, and will show how it can be used in a variety of applications either to unravel complex multi-step reaction mechanisms or to provide information on gas-phase molecular structures.

–

Publication: C. S. Slater, S. Blake, M. Brouard, A. Lauer, C. Vallance. J. J. John, R. Turchetta, A. Nomerotski, L. Christensen, J. H. Nielsen, M. P. Johansson, and H. Stapelfeldt, 'Covariance imaging experiments using the Pixel Imaging Mass Spectrometry camera', Phys. Rev. A., 89 011401(R) (2014).<br><br>C. S. Slater, S. Blake, M. Brouard, A. Lauer, C. Vallance, C. S. Bohun, L. Christensen, J. H. Nielsen, M. P. Johansson, and H. Stapelfeldt, ‘Coulomb explosion imaging using a Pixel Imaging Mass Spectrometry camera’, Phys. Rev. A., 91, 053424 (2015).<br><br>M. Burt, K. Amini, J. W. L. Lee, L. Christiansen, R. R. Johansen, Y. Kobayashi, J. D. Pickering, C. Vallance, M. Brouard, and H. Stapelfeldt, ‘Gas-phase structural isomer identification by Coulomb explosion of aligned molecules’, J. Chem. Phys., 148, 091102 (2018).<br><br>H. Koeckert, D. Heathcote, J. W. L. Lee, W. Zhou, V. Richardson, and C. Vallance, ‘C-I and C-F bond-breaking dynamics in the dissociative electron ionization of CF3I’, Phys. Chem. Chem. Phys., 21, 14296-14305 (2019).<br><br>C. Vallance, Multi-mass velocity-map imaging of photoinduced and electron-induced chemistry, invited review article, Chem. Comm., 55, 6336 – 6352 (2019).<br><br>J. W. L. Lee, H. Kockert, D. Heathcote, D. Popat, R. T. Chapman, G. Karras, P. Majchrzak, E. Springate, and C. Vallance, ‘Three-dimensional covariance-map imaging of molecular structure and dynamics on the ultrafast timescale’, Communications Chemistry, 3, 72 (2020).<br><br>H. Kockert, D. Heathcote, J. W. L. Lee, and Claire Vallance, ‘Covariance-map imaging study into the fragmentation dynamics of multiply charged CF3I formed in electron-molecule collisions’, Mol. Phys., 119, article e1811909 (2021).<br><br>C. Vallance, D. Heathcote, and J. W. L. Lee, Covariance-map imaging: a powerful tool for chemical dynamics studies, J. Phys. Chem. A, 125, 1117-1133 (2021).<br><br>D. Heathcote and C. Vallance, ‘Partial and contingent recoil-frame covariance-map imaging, J. Phys. Chem. A, 125(32), 7092-7098 (2021).

Presenters

  • Patrick Robertson

    University of Oxford

Authors

  • Claire Vallance

    University of Oxford

  • Patrick Robertson

    University of Oxford