Exploring the Spatial Features of Electronic Transitions in Molecular and Biomolecular Systems by Swift Electrons.

Ciro A Guido, Enzo Rotunno, Matteo Zanfrognini, Stefano Corni, Vincenzo Grillo

Journal of chemical theory and computation 2021 Apr 13

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We devise a new kind of experiment that extends the technology of electron energy loss spectroscopy to probe (supra-)molecular systems: by using an electron beam in a configuration that avoids molecular damage and a very recently introduced electron optics setup for the analysis of the outcoming electrons, one can obtain information on the spatial features of the investigated excitations. Physical insight into the proposed experiment is provided by means of a simple but rigorous model to obtain the transition rate and selection rule. Numerical simulations of DNA G-quadruplexes and other biomolecular systems, based on time dependent density functional theory calculations, point out that the conceived new technique can probe the multipolar components and even the chirality of molecular transitions, superseding the usual optical spectroscopies for those cases that are problematic, such as dipole-forbidden transitions, at a very high spatial resolution.

Citation

Ciro A Guido, Enzo Rotunno, Matteo Zanfrognini, Stefano Corni, Vincenzo Grillo. Exploring the Spatial Features of Electronic Transitions in Molecular and Biomolecular Systems by Swift Electrons. Journal of chemical theory and computation. 2021 Apr 13;17(4):2364-2373