Signature of two-electron interference in angular resolved double photoionization of Mg

The double photoionization of Mg has been studied experimentally and theoretically in a kinematic where the two photoelectrons equally share the excess energy. The observation of a symmetrized gerade amplitude, which strongly deviates from the Gaussian ansatz, is explained by a two-electron interference predicted theoretically, but never before observed experimentally. Similar to the Cooper minima in the single photoionization cross section, the effect finds its origin in the radial extent and oscillation of the target wave function

A procedure to extract the complex amplitudes of He photodouble ionization from experimental data

A procedure to extract the two complex amplitudes that govern the He photodouble ionization process from the experimental data is proposed. The results are compared with the predictions of the convergent close coupling and hyperspherical R-matrix with semiclassical outgoing wave theories

Photo-double-ionization of water at 20 eV above threshold

The photodouble ionization of the water molecule is studied at 20 eV excess energy in a combined experimental and theoretical investigation. In the experiments, two photoelectrons of equal kinetic energy are detected in coincidence after energy and angular selection. On the theoretical side, a generalized Sturmian function approach is implemented to describe accurately the correlated two-electron continuum, while separable products of Moccia orbitals [J. Chem. Phys. 40, 2164 (1964)JCPSA60021-960610.1063/1.1725489] are used for the initial electronic state of the water molecule. The theoretical triple-differential cross sections (TDCSs) are averaged over all possible molecular orientations in order to be compared with the experiments. The measured TDCSs display rich angular distributions that are in large part well reproduced by the adopted first-order treatment of the interaction with a two-active-electron target.Fil: Randazzo, Juan Martin. Comisión Nacional de Energía Atómica. Gerencia del Área de Energía Nuclear. Instituto Balseiro; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte; ArgentinaFil: Turri, G.. Embry-riddle Aeronautical University, Physical Sciences; Estados UnidosFil: Bolognesi, P.. CNR-Istituto di Struttura della Materia; ItaliaFil: Mathis, J.. Embry-riddle Aeronautical University, Physical Sciences; Estados UnidosFil: Ancarani, L. U.. Université de Lorraine; FranciaFil: Avaldi, L.. CNR-Istituto di Struttura della Materia; Itali

Signature of two-electron interference in angular resolved double photoionization of Mg

The double photoionization of Mg has been studied experimentally and theoretically in a kinematic where the two photoelectrons equally share the excess energy. The observation of a symmetrized gerade amplitude, which strongly deviates from the Gaussian ansatz, is explained by a two-electron interference predicted theoretically, but never before observed experimentally. Similar to the Cooper minima in the single photoionization cross section, the effect finds its origin in the radial extent and oscillation of the target wave function

A Combined Experimental and Theoretical Study of Photodouble Ionization of Water at 32 eV Excess Energy and Unequal Energy Sharing

In this paper we present a part of our investigation of the photodouble ionization (PDI) of gaseous water. Synchrotron radiation from ELETTRA storage ring was used to ionize the water molecule, and the two emitted electrons were collected in coincidence after angle and energy selection. We have compared the measured dication states with those known from literature and showed the angular distributions of the two photoelectrons measured for the first time, for different excess energies and under different energy sharing conditions. A detailed comparison with theoretical calculations is given to help understand some details of the PDI mechanism.Fil: Penson, Conner. Embry-riddle Aeronautical University; Estados UnidosFil: Turri, Giorgio. Full Sail University; Estados UnidosFil: Avaldi, Lorenzo. Consiglio Nazionale delle Ricerche; ItaliaFil: Randazzo, Juan Martin. Comisión Nacional de Energí­a Atómica. Gerencia del Area Investigación y Aplicaciones No Nucleares. Gerencia de Física (Centro Atómico Balseiro). División Colisiones Atómicas; Argentina. University of Central Florida; Estados Unidos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte; ArgentinaFil: Ancarani, Lorenzo Ugo. Université de Lorraine; FranciaFil: Bolognesi, Paola. Consiglio Nazionale delle Ricerche; Itali

Two electron interference in angular resolved double photoionization of Mg

The signature of the target wavefunction has been observed in the symmetrized amplitude of the resonant double photoionization of Mg. This observation is based on our experimental study of angle-resolved double photoionization of Mg at the photon energy of 55.49 eV (2p → 3d resonance) under equal energy sharing conditions

Interplay of the volume and surface plasmons in the electron energy loss spectra of C60_{60}

The results of a joint experimental and theoretical investigation of the C60 collective excitations in the process of inelastic scattering of electrons are presented. The shape of the electron energy loss spectrum is observed to vary when the scattering angle increases. This variation arising due to the electron diffraction of the fullerene shell is described by a new theoretical model which treats the fullerene as a spherical shell of a finite width and accounts for the two modes of the surface plasmon and for the volume plasmon as well. It is shown that at small angles, the inelastic scattering cross section is determined mostly by the symmetric mode of the surface plasmon, while at larger angles, the contributions of the antisymmetric surface plasmon and the volume plasmon become prominent.Comment: 11 pages, 3 figure

Interplay of post collision interaction and photoelectron recapture in the near threshold inner shell ionization of rare gases

The Ar 2p?11/2 n?, Kr 3d1/2?1 n? and Xe 4d?11/2 n? resonances have been photoexcited and the angular distributions of the low energy electrons ejected in the autoionistaion to the lower spin orbit component of the respective ions have been measured. The observed lineshapes can be described by a combination of the post-collision interaction effects and the electron recapture probability in the very near threshold region

An experimental and theoretical study of the resonant Auger spectrum of the ethene molecule

Resonant Auger spectra of the ethene molecule excited at energies across the C1s → π* energy band are reported. Our measurements address the unexpected variation of the intensity of the A state with respect to the other singly ionized valence states. An approach, based on group theory and calculations using Coulomb 4-center integrals, is proposed to explain the behaviour of the intensity of the ground state and excited states of the ion upon resonant excitation. The new method provides a calculationally inexpensive route to predict relative intensities of different resonant Auger bands in polyatomic molecules, without the need for an exhaustive knowledge of the potential energy surfaces of the electronic states involved

H2O ̇+ and OH+ reactivity versus furan: experimental low energy absolute cross sections for modeling radiation damage

Radiotherapy is one of the most widespread and efficient strategies to fight malignant tumors. Despite its broad application, the mechanisms of radiation-DNA interaction are still under investigation. Theoretical models to predict the effects of a particular delivered dose are still in their infancy due to the difficulty of simulating a real cell environment, as well as the inclusion of a large variety of secondary processes. This work reports the first experimental study of the ion-molecule reactions of the H2O ̇+ and OH+ ions, produced by photoionization with synchrotron radiation, with a furan (c-C4H4O) molecule, a template for deoxyribose sugar in DNA. The present experiments, performed as a function of the collision energy of the ions and the tunable photoionization energy, provide key parameters for the theoretical modelling of the effect of radiation dose, like the absolute cross sections for producing protonated furan (furanH+) and a radical cation (furan ̇+), the most abundant products, which can amount up to 200 Å2 at very low collision energies (<1.0 eV). The experimental results show that furanH+ is more fragile, indicating how the protonation of the sugar component of the DNA may favor its dissociation with possible major radiosensitizing effects. Moreover, the ring opening of furanH+ isomers and the potential energy surface of the most important fragmentation channels have been explored by molecular dynamics simulations and quantum chemistry calculations. The results show that, in the most stable isomer of furanH+, the ring opening occurs via a low energy pathway with carbon-oxygen bond cleavage, followed by the loss of neutral carbon monoxide and the formation of the allyl cation CH2CHCH2+, which instead is not observed in the fragmentation of furan ̇+. At higher energies the ring opening through the carbon-carbon bond is accompanied by the loss of formaldehyde, producing HCCCH2+, the most intense fragment ion detected in the experiments. This work highlights the importance of the secondary processes, like the ion-molecule reactions at low energies in the radiation damage due to their very large cross sections, and it aims to provide benchmark data for the development of suitable models to approach this low collision energy range