Dressed projectile charge state dependence of differential electron emission from Ne atom

We study the projectile charge state dependence of doubly differential electron emission cross section (DDCS) in ionization of Ne under the impact of dressed and bare oxygen ions. Experimental DDCS results measured at different angles are compared with the calculations based on a CDW-EIS approximation using the GSZ model potential to describe projectile active-electron interaction. This prescription gives an overall very good agreement. In general a deviation from the q2-law was observed in the DDCS. The observations crudely identify the dominance of different projectile electron loss mechanisms at certain electron energy range.Fil: Biswas, S.. Tata Institute of Fundamental Research; IndiaFil: Monti, Juan Manuel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Física de Rosario. Universidad Nacional de Rosario. Instituto de Física de Rosario; ArgentinaFil: Rivarola, Roberto Daniel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Física de Rosario. Universidad Nacional de Rosario. Instituto de Física de Rosario; ArgentinaFil: Tribedi, L. C.. Tata Institute of Fundamental Research; Indi

X-ray emission from aluminium under intense, ultrashort irradiation

We present studies of X-ray emission from aluminium under picosecond and femtosecond irradiation in the intensity range ~ 1012-1015 W cm-2. We use a new and simple method to measure spectrally resolved absolute X-ray yields. It is shown that the X-ray yields can be obtained for arbitrary levels of X-ray flux. We present details of the variation of the absolute yields as a function of wavelength, intensity, polarization and pulse duration of the incident laser radiation. Electron temperatures in the keV range are observed at 1015 W cm-2 with femtosecond laser pulses

Two-Center Effect on Low-Energy Electron Emission in Collisions of 1-MeV/u Bare Ions with Atomic Hydrogen, Molecular Hydrogen, and Helium: II. H\u3csub\u3e2\u3c/sub\u3e and He

We have studied the energy and angular distributions of low-energy electron emission in collisions of bare carbon ions of 1-MeV/u energy with He and H2 targets. The double-differential cross sections (DDCS’s) are measured for electrons with energies between 0.5 and 300 eV emitted within an angular range of 15° to 160°. The large forward-backward asymmetry observed in the angular distributions is explained in terms of the two-center effect. Single differential cross sections (SDCS’s) and total cross sections are also derived by integrating the DDCS’s over emission angles and energies. The data are compared with different theoretical calculations based on the first Born, CDW (continuum-distorted-wave), and CDW-EIS (eikonal-initial-state) approximations. The angular distributions of DDCS’s and SDCS’s are shown to deviate largely from the predictions of the B1 calculations, and are in much better agreement with both the continuum distorted-wave models. The CDW approximation provides a better agreement with the data compared to the CDW-EIS approximation, especially at higher electron energies. The total ionization cross sections for all three targets are shown to follow a scaling rule approximately

Two-Center Effect on Low-Energy Electron Emission in Collisions of 1-MeV/u Bare Ions with Atomic Hydrogen, Molecular Hydrogen, and Helium: II. H\u3csub\u3e2\u3c/sub\u3e and He

We have studied the energy and angular distributions of low-energy electron emission in collisions of bare carbon ions of 1-MeV/u energy with He and H2 targets. The double-differential cross sections (DDCS’s) are measured for electrons with energies between 0.5 and 300 eV emitted within an angular range of 15° to 160°. The large forward-backward asymmetry observed in the angular distributions is explained in terms of the two-center effect. Single differential cross sections (SDCS’s) and total cross sections are also derived by integrating the DDCS’s over emission angles and energies. The data are compared with different theoretical calculations based on the first Born, CDW (continuum-distorted-wave), and CDW-EIS (eikonal-initial-state) approximations. The angular distributions of DDCS’s and SDCS’s are shown to deviate largely from the predictions of the B1 calculations, and are in much better agreement with both the continuum distorted-wave models. The CDW approximation provides a better agreement with the data compared to the CDW-EIS approximation, especially at higher electron energies. The total ionization cross sections for all three targets are shown to follow a scaling rule approximately

L-MM Auger electron emission from chlorinated organic molecules under proton impact: angular distribution and total cross section measurement

We have measured absolute total cross section for LMM Auger electron emission of Cl in chlorinated methane and benzene chloride in collision with H+ ion. Projectile energy dependence of the total yield as well as the angular distribution has been studied. Incident proton energy has been varied from 125 keV to 275 keV in steps of 50 keV. C KLL Auger yield have been compared with previous studies and found to be in agreement within the effect of chemical species It has been found that the LMM Auger yield of Cl is much more significantly affected by molecular environment than the C KLL

Fragmentation dynamics of diatomic molecules under proton impact: Kinetic energy release spectra of CO^{q+} and NO^{q+} (q = 2, 3) molecular ions

We report on the fragmentation dynamics of triply charged, diatomic, molecular ions of NO and CO. Dissociative fragmentation after multiple ionization of NO and CO is studied under the impact of 200 keV proton beam using recoil-ion momentum spectrometer. Kinetic Energy Release distributions (KERDs) for various fragmentation channels were obtained. We have also calculated the potential energy curves (PECs) for ground and several excited states of NO^{3+} and CO^{3+} molecular ion. The obtained KERDs are discussed in the background of the calculated PECs as well as the simple Coulomb excitation model. Coulomb breakup of the unstable precursor molecular ion shows a clear preference for the N^{2+} + O^+ (and C^{2+} + O^+) fragmentation channel.Comment: 8 pages, 6 figures, 3 table

Two-Center Effect on Low-Energy Electron Emission in Collisions of 1-MeV/u Bare Ions with Atomic Hydrogen, Molecular Hydrogen, and Helium. I. Atomic Hydrogen

We have investigated ionization mechanisms in fast ion-atom collisions by measuring the low-energy electron emission cross sections in a pure three-body collision involving bare carbon ions (v=6.35 a.u.) colliding with atomic hydrogen targets. The measurements have also been extended to molecular hydrogen and helium targets. In this paper we provide the energy and angular distributions of double differential cross sections of low-energy electron emission for atomic hydrogen targets. The Slevin rf source with a high degree of dissociation was used to produce the atomic H target. It is found that the two-center effect has a major influence on the observed large forward-backward angular asymmetry. A detailed comparison is presented with calculations based on the continuum distorted-wave (CDW) and CDW-EIS (eikonal initial-state) approximations. Both the continuum distorted-wave calculations provide a very good understanding of the data, whereas the first Born calculation predicts almost symmetric forward-backward distributions that do not agree with the data. The two-center effect is slightly better represented by the CDW calculations compared to the CDW-EIS calculation. The total cross sections are, however, in good agreement with the theories used. The results for molecular hydrogen and helium will be discussed in the following paper