Our recent study Aiswarya (2024 Phys. Rev. Lett. 133 033002) accessed the angle-energy two-dimensional diffraction in elastic electron scattering from C60 with implications for ultrafast electron diffraction studies. The objective of the current investigation is to carry out a detailed characterization of the Fourier transformed signals of diffraction fringes in the angular distribution for a range of impact energies. Results shed light on how the electron's perception of the molecular target evolves as a function of its de Broglie wavelength and tends to be geometrically accurate at faster impacts. For very fast impacts and the resulting dominance of high angular momentum partial waves, the target becomes partly hidden within a spherical shell of repulsive centrifugal barrier, from which the electron 'self-diffracts'. This effect is favored by the polarization interaction of C60. Potentials from a jellium-based density functional theory within the local density approximation and an annular square well model are independently applied to simulate the C60 environment. Results from the partial wave analysis and Born approximation are independently analyzed by a fast Fourier transformation technique.

We study the ground state structure and aspects of photoionization dynamics of the Na20@C240 endofullerene. The structure shows effects from the electronic coupling between the nested cluster and the fullerene cage. They include the (i) alterations of the overall potential, and thus, the force field, (ii) electron transfer from the cluster to the fullerene forming ionic units, and (iii) hybridization from the admixture of free Na20 occupied levels with experimentally known super-atom molecular orbital (SAMO) type empty levels of C240 accessible in the jellium-density functional theory model. These modifications influence the photoionization dynamics of the endofullerene. For the high energy ionization of Na20-type levels, a significant overall enhancement of the cross section is noted from additional ionizing force that C240 offers. More remarkably, the photoexcited plasmons, both the giant plasmon and the higher energy plasmon, in C240 decay in parts through Na20 ionization continuum via the resonant intercluster Coulombic decay (ICD) process. These lead to dramatic enhancements in the ionization of individual Na20-type levels, resulting in enhancements in the cluster's total ionization yield. Based on hybridization, this enhancement incorporates a coherent mixing of the ICD and SAMO-induced Auger-decay amplitude, in which the ICD contribution is dominant.

Plane-wave electrons undergo momentum transfer as they scatter off a target in overlapping spherical waves. The transferred momentum leads to target structural information to be encoded in angle and energy differential scattering. For symmetric, periodic, or structured targets this can engender diffraction in the electron intensity both in real and momentum space. With the example of elastic scattering from a C_{60} molecule we show these simultaneous diffraction signatures. Simulated angle-momentum diffractograms can be imaged in experiments with a two-dimensional detector and an energy-tunable electron gun. The result may inspire the invention of technology to extend scopes of electron diffraction studies, open a track of electron crystallography using the momentum-differential diffraction, and motivate research about controlling the time delay between the pump laser pulse and probe electron pulse by tuning the electron impact speed in ultrafast electron diffraction experiments.

We study the ground state structure and aspects of photoionization dynamics of the $Na_{20}@C_{240}$ endofullerene. The structure shows effects from the electronic coupling between the nested cluster and the fullerene cage. They include the (i) alterations of the overall potential, and thus, the force field, (ii) electron transfer from the cluster to the fullerene forming ionic units, and (iii) hybridization from the admixture of free $Na_{20}$ occupied levels with experimentally known super-atom molecular orbital (SAMO) type empty levels of $C_{240}$ accessible in the jellium-DFT model. These modifications influence the photoionization dynamics of the endofullerene. For the high energy ionization of $Na_{20}$-type levels, a significant overall enhancement of the cross section is noted from additional ionizing force that $C_{240}$ offers. More remarkably, the photoexcited plasmons, both the giant plasmon and the higher energy plasmon, in decay in parts through $Na_{20}$ ionization continuum via the resonant intercluster Coulombic decay (ICD) process. These lead to dramatic enhancements in the ionization of individual $Na_{20}$-type levels resulting enhancements in the cluster's total ionization yield. Based on hybridization, this enhancement incorporates a coherent mixing of the ICD and SAMO-induced Auger-decay amplitude, in which the ICD contribution is dominant.

Access to time delay in a projectile-target scattering is a fundamental tool in understanding their interactions by probing the temporal domain. The present study focuses on computing and analyzing the Eisenbud-Wigner-Smith (EWS) time delay in low energy elastic e−C60 scattering. The investigation is carried out in the framework of a non-relativistic partial wave analysis (PWA) technique. The projectile-target interaction is described in (i) Density Functional Theory (DFT) and (ii) Annular Square Well (ASW) static model, and their final results are compared in details. The impact of polarization on resonant and non-resonant time delay is also investigated.

Light-induced energy confinement in nanoclusters via plasmon excitations influences applications in nanophotonics, photocatalysis, and the design of controlled slow electron sources. The resonant decay of these excitations through the cluster's ionization continuum provides a unique probe of the collective electronic behavior. However, the transfer of a part of this decay amplitude to the continuum of a second conjugated cluster may offer control and efficacy in sharing the energy nonlocally to instigate remote collective events. With the example of a spherically nested dimer Na_{20}@C_{240} of two plasmonic systems we find that such a transfer is possible through the resonant intercluster Coulombic decay (RICD) as a fundamental process. This plasmonic RICD signal can be experimentally detected by the photoelectron velocity map imaging technique.

The ground state and photoionization properties of Nax (x = 20, 40, and 92) clusters are investigated using a method based on density functional theory (DFT) in a spherical jellium frame. Two different exchange–correlation treatments with the Gunnarsson–Lundqvist parametrization are used: (i) the electron self-interaction correction (SIC) scheme and (ii) the van Leeuwen–Baerends (LB94) scheme based on the gradient of the electron density. The shapes of the mean-field potentials and bound state properties, obtained in the two schemes, qualitatively agree, but differ in the details. The effect of the schemes on the photoionization dynamics, calculated in linear response time-dependent DFT is compared, in which the broader features are found to be universal. The general similarity of the results in SIC and LB94 demonstrates the reliability of DFT treatments. The study further elucidates the evolution of the ground state and ionization description as a function of the cluster size.

The 53rd Annual Meeting of the APS Division of Atomic, Molecular and Optical Physics will take place from May 30 – June 3, 2022 in Orlando, Fl, USA. Virtual Presenter Help Desk

The 53rd Annual Meeting of the APS Division of Atomic, Molecular and Optical Physics will take place from May 30 – June 3, 2022 in Orlando, Fl, USA. Virtual Presenter Help Desk

Photoionization studies of Na20 and Na92 clusters are carried out in a framework of linear response density functional theory. Cross sections show substantial spillover of plasmon resonances to the near-threshold ionization energies which are in reasonable agreements with photoabsorption measurements. The analysis of the oscillator strength, consumed by the cross section, lends further detailed insights. The many-body interaction induced self-consistent field from density fluctuations suggests the existence of an attractive force. This may cause time-delayed plasmonic photoemissions in ultrafast measurements. At the waning end of the plasmon structure, a strong minimum in the cross sections from a correlation-driven coherence effect is predicted which can possibly be observed by the photoelectron spectroscopy.

We study the ground state structure and aspects of photoionization dynamics of the Na_20@C_240 endofullerene. The structure shows effects from the electronic coupling between the nested cluster and the fullerene cage. They include the (i) alterations of the overall potential, and thus, the force field, (ii) electron transfer from the cluster to the fullerene forming ionic units, and (iii) hybridization from the admixture of free Na_20 occupied levels with experimentally known super-atom molecular orbital (SAMO) type empty levels of C_240 accessible in the jellium-DFT model. These modifications influence the photoionization dynamics of the endofullerene. For the high energy ionization of Na_20-type levels, a significant overall enhancement of the cross section is noted from additional ionizing force that C_240 offers. More remarkably, the photoexcited plasmons, both the giant plasmon and the higher energy plasmon, in decay in parts through Na_20 ionization continuum via the resonant intercluster Coulombic decay (ICD) process. These lead to dramatic enhancements in the ionization of individual Na_20-type levels resulting enhancements in the cluster's total ionization yield. Based on hybridization, this enhancement incorporates a coherent mixing of the ICD and SAMO-induced Auger-decay amplitude, in which the ICD contribution is dominant.

We study the photoionization properties of the Na-n (n=40 and 92) clusters in a spherical jellium frame using the Kohn-Sham density functional method. Two well known form of exchange-correlation (xc) functional in the framework of local density approximation (LDA) with Gunnarsson-Lundqvist parametrization[1] are employed: i) the electron self-interaction correction (LDA-SIC) [1] and ii) the van Leeuwen and Baerends model potential (LDA-LB94) [1].