The electron scattering from the nested fullerene system C60@C240, the smallest stable carbon nano-onion, is investigated in the present work. Resonance features appearing in the total cross sections of nested fullerenes are analyzed by comparing those from the individual cages. It reveals the emergence of a window resonance, unique to the hybrid system. The impact of resonances on the differential cross section is also examined. To further elucidate the scattering dynamics, the studies are extended to the time domain by calculating the EisenbudWigner-Smith and angular time delays. The studies, therefore, provide a qualitative analysis of the scattering process of a nested system and serve as a basis for understanding and controlling the dynamics of electron scattering from complex fullerene systems.

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.

Coulomb confinement resonances (CCRs) are the main features of the photoionization spectra of an atom inside an anionic fullerene. These CCRs can act as an amplifier to spin-orbit-interaction-activated interchannel coupling (SOIAIC) and can lead to discernible signatures of relativistic effects even for low Z confined atomic systems. The present paper demonstrates this intriguing feature by studying angular photoemission time delay of the 2p3/2 subshell of Ar@C-160 in the vicinity of the 2p1/2 ionization threshold. Here 2p1/2 CCR functions as an amplifier to the SOIAIC and, thereby, induces significant modifications in the 2p3/2 angular time delay through the interchannel coupling. Moreover, the effects of the SOIAIC for the spin-up and spin-down photoelectrons are found to be different. All of these suggest that angle-resolved time-delay measurements can reveal the relativistic effects even for the low Z confined atomic systems, and Ar@C-160 is a potential candidate for such experimental scrutiny. The impact of the model parameters on the predicted feature is also critically examined by using different sets of parameters. All of those calculations showed the existence of SOIAIC enabled structures in the angular time-delay profile.

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.

A procedure to obtain relativistic expressions for photoionisation angular distribution parameters using the helicity formulation is discussed for open-shell atoms. Electric dipole and quadrupole transition matrix elements were considered in the present work, to study the photoionisation dynamics of the 3s electron of the sodium atom in the vicinity of the dipole Cooper minimum. We studied dipole–quadrupole interference effects on the photoelectron angular distribution in the region of the dipole Cooper minimum. Interference with quadrupole transitions was found to alter the photoelectron angular distribution, even at rather low photon energies. The initial ground and final ionised state discrete wavefunctions of the atom were obtained in the present work using GRASP, and we employed RATIP with discrete wavefunctions, to construct continuum wavefunctions and to calculate transition amplitudes, total cross-sections and angular distribution asymmetry parameters.

Atomic, molecular, and optical (AMO) physics is a vastly important sub-discipline [...]

The present work reports the photoionisation studies of 2 p subshell of Na atom, just above the threshold region. The calculations are performed in the framework of multiconfiguration Dirac–Hartree–Fock method (MCDHF). It unravels the effect of 3d orbital on the final state leading to the appearance of Cooper minimum (CM) in the region close to the threshold. Further, the impact of this CM on the angular distribution parameter is studied. It is found that CM not only modifies the cross section profile but also makes dramatic changes in the angular distribution.

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

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.

The photoionization dynamics of the inner subshell of an endohedral anion, Ar@C-60(q=-4), using relativistic random phase approximation (RRPA), is investigated. The charged nature of the fullerene induces Coulomb confinement resonances (CCRs) not only on the 2s cross-section but also on other dynamical attributes such as angular distribution asymmetric parameter, phase shift, and time delay of the same subshell. More importantly, we find that the 2s CCRs resurrect confinement resonances into the photoionization dynamics of 3s ionization channels at energies far away from the 3s threshold. The impacts of the revivification of these resonances on the 3s cross-section, phase shift, and time delay are explored in this work.

The photoionization cross-section of an atom trapped inside a fullerene anion in the near-threshold region is dominated by the Coulomb confinement resonances. These prominent structures facilitate the possibility of an enhanced spin-orbit interaction activated interchannel coupling (SOIAIC) leading to significant modifications of the photoionization parameters even for low-Z confined atomic systems. The existence of such confinement enhanced SOIAIC structures are demonstrated for the relativistically split 2p ionization channels of Ar trapped inside fullerene anion. Dramatic modifications are observed not only in the cross-sections but also in the angular distributions, and relative phases between the degenerate channels present. Similar structures are found for the case of confined Kr as well. A detailed analysis of these interesting features is carried out which showed the importance of correlation and relativistic effects on the photoionization dynamics of confined atomic systems.

Confined atomic systems are of great importance owing a multitude of possible applications in various areas of science and technology. Of particular interest are atoms encaged in the $$\hbox {C}_{{60}}$$ molecule, $$\hbox {A}@\hbox {C}_{{60}}$$ , since the near-spherical symmetry of $$\hbox {C}_{{60}}$$ simplifies theoretical studies, and the stability of $$\hbox {C}_{{60}}$$ renders it amenable to experimental examination. A review of investigations of the electronic structure and dynamics of $$\hbox {A}@\hbox {C}_{{60}}$$ is presented in this manuscript focusing on developments in the last decade. Addressed mainly are how the confinement affects electronic structure properties such as ionization potentials, localization of atomic electrons, Shannon entropy, correlation effects, relativistic interactions, and others. In the area of dynamics, photoionization and e- $$\hbox {A}@\hbox {C}_{{60}}$$ scattering are reviewed and summarized, and the major effects of confinement on the dynamical properties, e.g., confinement resonances, hybridization, Wigner time delay, are delineated.

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.