We present a study on molecular-frame photoelectron angular distributions (MFPADs) of small molecules using circularly polarized synchrotron light. We find that the main forward-scattering peaks of the MFPADs are slightly tilted with respect to the molecular axis. This tilt angle is directly connected to the molecular bond length by a simple, universal formula. We apply the derived formula to several examples of MFPADs of C 1s and O 1s photoelectrons of CO, which have been measured experimentally or obtained by means of modeling. In addition, we discuss the influence of the back-scattering contribution that is superimposed over the analyzed forward-scattering peak in the case of homo-nuclear diatomic molecules such as N.
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http://dx.doi.org/10.1039/d2cp05942h | DOI Listing |
Phys Chem Chem Phys
October 2024
Department of Chemistry, Tohoku University, 6-3 Aramaki Aza-Aoba, Aoba-ku, Sendai 980-8578, Japan.
Phys Chem Chem Phys
August 2024
Sorbonne Université, CNRS, UMR 7614, Laboratoire de Chimie Physique-Matière et Rayonnement, F-75005 Paris, France.
Photoelectron recoil strongly modifies the high kinetic energy photoemission spectra from atoms and molecules as well as from surface structures. In most cases studied so far, photoemission from atomic-like inner-shell or core orbitals has been assumed to be isotropic in the molecular frame of reference. However, in the presence of molecular field splitting of p or d orbitals, this assumption is not justified .
View Article and Find Full Text PDFJ Phys Chem A
February 2024
Departamento de Química, Universidad Autónoma de Madrid, Madrid 28049, Spain.
The recent implementation of attosecond and few-femtosecond X-ray pump/X-ray probe schemes in large-scale free-electron laser facilities has opened the way to visualize fast nuclear dynamics in molecules with unprecedented temporal and spatial resolution. Here, we present the results of theoretical calculations showing how polarization-averaged molecular-frame photoelectron angular distributions (PA-MFPADs) can be used to visualize the dynamics of hydrogen migration in methanol, ethanol, propanol, and isopropyl alcohol dications generated by X-ray irradiation of the corresponding neutral species. We show that changes in the PA-MFPADs with the pump-probe delay as a result of intramolecular photoelectron diffraction carry information on the dynamics of hydrogen migration in real space.
View Article and Find Full Text PDFPhys Chem Chem Phys
May 2023
European XFEL, Holzkoppel 4, 22869 Schenefeld, Germany.
We present a study on molecular-frame photoelectron angular distributions (MFPADs) of small molecules using circularly polarized synchrotron light. We find that the main forward-scattering peaks of the MFPADs are slightly tilted with respect to the molecular axis. This tilt angle is directly connected to the molecular bond length by a simple, universal formula.
View Article and Find Full Text PDFJ Chem Phys
April 2023
Departamento de Química, Facultad de Ciencias, Universidad Autónoma de Madrid, Madrid, Spain.
We have evaluated total and partial photoionization cross sections, β asymmetry parameters, and molecular frame photoelectron angular distributions (MFPADs) of the water molecule by using the XCHEM methodology. This method accounts for electron correlation in the electronic continuum, which is crucial to describe Feshbach resonances and their autoionization decay. We have identified a large number of Feshbach resonances, some of them previously unknown, in the region between 12.
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