Imaging intramolecular hydrogen migration with time- and momentum-resolved photoelectron diffraction

Imaging ultrafast hydrogen migration with few- or sub-femtosecond time resolution is a challenge for ultrafast spectroscopy due to the lightness and small scattering cross-section of the moving hydrogen atom. Here we propose time- and momentum-resolved photoelectron diffraction (TMR-PED) as a way to overcome limitations of existing methodologies and illustrate its performance in the ethanol molecule. By combining different theoretical methods, namely molecular dynamics and electron scattering methods, we show that TMR-PED, along with a judicious choice of the reference frame for multi-coincidence detection, allows for direct imaging of single and double hydrogen migration in doubly-charged ethanol with both few-fs and Å resolutions, all the way from its birth to the very end. It also provides hints of proton extraction following H2 roaming. The signature of hydrogen dynamics shows up in polarization-averaged molecular-frame photoelectron angular distributions (PA-MFPADs) as moving features that allow for a straightforward visualization in spaceThis work was performed under the European COST Action CA18222 AttoChem and Cooperative Research Program of ‘‘Network Joint Research Center for Materials and Devices.’’ K. H. acknowledges funding by JSPS KAKENHI under Grant No. 18K05027 and 17K04980. This work was partially funded by the Spanish Ministry of Science and Innovation – Ministerio Español de Ciencia e Innovación MICINN – projects PID2019-105458RB-I00 and PID2019-110091GB-I00, the Severo Ochoa Programme for Centres of Excellence in R & D (SEV-2016-0686) and the María de Maeztu Programme for Units of Excellence in R & D (CEX2018-000805-M

Effects of Sultopride and Sulpiride on Serum Prolactin Level in Schizophrenia.

Sultopride or sulpiride was administered to 26 schizophrenic patients. In the male patients, there was a significant correlation between serum concentrations of sultopride and sulpiride and prolactin response. In the female patients, there was no significant correlation between them. In sultopride treatment, prolaction response was suggested to be predictive of a good therapeutic response

High-Energy Molecular-Frame Photoelectron Angular Distributions: A Molecular Bond-Length Ruler

We present an experimental and theoretical study of core-level ionization of small hetero- and homo-nuclear molecules employing circularly polarized light and address molecular-frame photoelectron angular distributions in the light's polarization plane (CP-MFPADs). We find that the main forward-scattering peaks of CP-MFPADs are slightly tilted with respect to the molecular axis. We show that this tilt angle can be directly connected to the molecular bond length by a simple, universal formula. The extraction of the bond length becomes more accurate as the photoelectron energy is increased. We apply the derived formula to several examples of CP-MFPADs of C 1s and O 1s photoelectrons of CO, which have been measured experimentally or obtained by means of ab initio modeling. The photoelectron kinetic energies range from 70 to 1000~eV and the extracted bond lengths agree well with the known bond length of the CO molecule in its ground state. In addition, we discuss the influence of the back-scattering contribution that is superimposed over the analyzed forward-scattering peak in case of homo-nuclear diatomic molecules as N$_2$

Theory of polarization-averaged core-level molecular-frame photoelectron angular distributions: III. New formula for p- and s-wave interference analogous to Young’s double-slit experiment for core-level photoemission from hetero-diatomic molecules

International audienceWe present a new variation of Young's double-slit formula for polarization-averaged molecular-frame photoelectron angular distributions (PA-MFPADs) of hetero-diatomic molecules, which may be used to extract the bond length. So far, empirical analysis of the PA-MFPADs has often been carried out employing Young's formula in which each of the two atomic centers emits a s-photoelectron wave. The PA-MFPADs, on the other hand, can consist of an interference between the p-wave from the X-ray absorbing atom emitted along the molecular axis and the s-wave scattered by neighboring atom, within the framework of Multiple Scattering theory. The difference of this p-s wave interference from the commonly used s-s wave interference causes a dramatic change in the interference pattern, especially near the angles perpendicular to the molecular axis. This change involves an additional fringe, urging us to caution when using the conventional Young's formula for retrieving the bond length. We have derived a new formula analogous to Young's formula but for the p-s wave interference. The bond lengths retrieved from the PA-MFPADs via the new formula reproduce the original C-O bond lengths used in the reference ab-initio PA-MFPADs within the relative error of 5 %. In the high energy regime, this new formula for p-s wave interference converges to the ordinary Young's formula for the s-s wave interference. We expect it to be used to retrieve the bond length for time-resolved PA-MFPADs instead of the conventional Young's formula

Theory of polarization-averaged core-level molecular-frame photoelectron angular distributions: I. A Full-potential method and its application to dissociating carbon monoxide dication

International audienceWe present a theoretical study of the polarization-averaged molecular-frame photoelectron angular distributions (PA-MFPADs) emitted from the 1s orbital of oxygen atoms of dissociating dicationic carbon monoxide CO2+. Due to the polarization-average, the contribution of the direct wave of the photoelectron which represents the largest contribution to the MFPADs is removed, so that the PA-MFPADs clearly show the details of the scattering image of the photoelectron. As a result, it is necessary to employ an accurate theory for the theoretical analysis of the continuum state. In this study, we apply a Full-potential Multiple Scattering theory, where the space is partitioned into Voronoi polyhedra and truncated spheres, in order to take into account the electron charge density outside the physical atomic spheres. We do not use the spherical harmonics expansion of the cell shape functions to avoid divergence problems. The potentials in the scattering cells are computed using the Multiconfigurational Second-Order Perturbation Theory Restricted Active Space (RASPT2) method in order to take into account the influence of the core hole in the electron charge density in the final state, so that to a realistic relaxation can be achieved. We show that the Full-potential treatment plays an important role in the PA-MFPADs at a photoelectron kinetic energy of 100 eV. By contrast, the PA-MFPADs are not sensitive to any type of major excited states in the Auger final state. We also study the dynamics of the CO2+ dissociation. We find that the PA-MFPADs dramatically change their shape as a function of the C-O bond length

Theory on polarization-averaged core-level molecular-frame photoelectron angular distributions: II. Extracting the X-ray induced fragmentation dynamics of carbon monoxide dication from forward and backward intensities

International audienceRecent developments in high repetition-rate X-ray free electron lasers (XFELs) such as the European XFEL and the LSCS-II, combined with coincidence measurements at the COLTRIMS--Reaction Microscope, is now opening a door to realize the long-standing dream to create molecular movies of photo-induced chemical reactions in gas-phase molecules. In this paper, we propose a new theoretical method to experimentally visualize the dissociation of diatomic molecules via time-resolved polarization-averaged molecular-frame photoelectron angular distributions (PA-MFPADs) measurements using the COLTRIMS--Reaction Microscope and the two-color XFEL pump-probe set-up. We used first and second order scattering theory within the Muffin-tin approximation, which is valid for a sufficiently high kinetic energy of photoelectron, typically above 100 eV, and for long bond lengths. This leads to a simple EXAFS-type formula for the forward and backward scattering peaks in the PA-MFPADs structure. This formula relies only on three semi-empirical parameters obtainable from the time-resolved measurements. It can be used as a "bond length ruler" on experimental results. The accuracy and applicability of the new ruler equation are numerically examined against the PA-MFPADs of CO2+ calculated with Full-potential multiple scattering theory as a function of the C-O bond length reported in the preceding work [1]. The bond lengths retrieved from the the PA-MFPADs via our EXAFS-like formula coincide within an accuracy of 0.1 Å with the original C-O bond lengths used in the reference ab-initio PA-MFPADs. We expect time-resolved PA-MFPADs to become a new attractive tool to make molecular movies visualizing intramolecular reactions