Rosetta mission: Electron scattering cross sections-data needs and coverage in BEAMDB database

The emission of [O I] lines in the coma of Comet 67P/Churyumov-Gerasimenko during the Rosetta mission have been explained by electron impact dissociation of water rather than the process of photodissociation. This is the direct evidence for the role of electron induced processing has been seen on such a body. Analysis of other emission features is handicapped by a lack of detailed knowledge of electron impact cross sections which highlights the need for a broad range of electron scattering data from the molecular systems detected on the comet. In this paper, we present an overview of the needs for electron scattering data relevant for the understanding of observations in coma, the tenuous atmosphere and on the surface of 67P/Churyumov-Gerasimenko during the Rosetta mission. The relevant observations for elucidating the role of electrons come from optical spectra, particle analysis using the ion and electron sensors and mass spectrometry measurements. To model these processes electron impact data should be collated and reviewed in an electron scattering database and an example is given in the BEAMD, which is a part of a larger consortium of Virtual Atomic and Molecular Data Centre-VAMDC

Study of electron transmission through a metallic capillary

In this work we study the transmission of charged particles through a single cylindrically shaped metallic capillary of microscopic dimensions with a large aspect ratio. We used electrons as projectiles. Our results suggest the existence of guiding of the electron beam by a metallic capillary.29th International Conference on Photonic, Electronic, and Atomic Collisions (ICPEAC), Jul 22-28, 2015, Toledo, Spai

Orange-Reddish Light Emitting Phosphor GdVO 4 :Sm 3+ Prepared by Solution Combustion Synthesis

The gadolinium vanadate doped with samarium (GdVO 4 :Sm 3+ ) nanopowder was prepared by the solution combustion synthesis (SCS) method. After synthesis, in order to achieve the full crystallinity, the material was annealed in air atmosphere at 900°C. Phase identification in the postannealed powder samples was performed by X-ray diffraction, and morphology was investigated by high-resolution scanning electron microscopy (SEM). Photoluminescence characterization of the emission spectrum and time-resolved analysis have been performed using the tunable laser optical parametric oscillator excitation and the streak camera. Several strong emission bands in the Sm 3+ emission spectrum were observed, located at 567 nm ( 4 G 5/2 – 6 H 5/2 ), 604 nm ( 4 G 5/2 – 6 H 7/2 ), and 646 (654) nm ( 4 G 5/2 – 6 H 9/2 ), respectively. The weak emission bands at 533 nm ( 4 F 3/2 – 6 H 5/2 ) and 706 nm ( 4 G 5/2 – 6 H 11/2 ) and a weak broad luminescence emission band of VO 4 3− were also observed by the detection system. We analyzed the possibility of using the host luminescence for two-color temperature sensing. The proposed method is improved by introducing the temporal dependence in the line intensity ratio measurements

New Data on Autoionizing States of Ne Induced by Low-Energy Electrons from 45 to 64 eV

The lowest single and doubly excited autoionizing states of neon have been studied using a non-monochromatic electron beam and a high-resolution electrostatic analyzer at incident electron energies from 43.37 to 202 (±0.4) eV at three ejection angles, 40°, 90° and 130°. The 2s2p63s(3,1S) and 2s2p63p(3,1P) as well as the 2p43s3p doubly excited states have been observed and their energy determined. The influence of the PCI effect in the energy region of the 2s2p63s(3,1S) states has been investigated. New features in the ejected electron spectra in the low kinetic energy region 3–20 eV at 202 eV incident energy have been observed and assigned

The Auger spectra in argon induced by electron impact – new measurements with high resolution

The Auger spectrum of argon in the kinetic energy region (135–235 eV) has been measured using a non-monochromatic electron beam (incident energy from 313 to 2019 eV) at two ejection angles of 60° and 90° with a high resolution electrostatic analyzer. The electron impact energies of 313 and 323 eV have been used in order to disentangle the contribution of the ionization and decay of the 2s state. The systematic analysis of the measured spectra shows the dominance of the Coster-Kronig transitions from the 2s ionization in the energy region 135–159 eV and 208–235 eV, while the Auger transitions from the 2p ionization are dominant in the energy region 160–208 eV. The high resolution of the present work led to the observation of a certain number of new features in two energy regions 135–159 and 208–235 eV, respectively. Recent literature data on the cascade Auger processes and threshold formation of Ar2+ satellite states allow the assignment of some of them, while other have been left without assignments. The influence of the PCI effect on the line-shape, width and energy position of the features in the kinetic energy region 200–208 eV has been also investigated and the PCI shift versus excess energy above threshold compared with previous data and theoretical predictions

Elastic electron differential cross sections for argon atom in the intermediate energy range from 40 eV to 300 eV

Measurements and calculations for electron elastic differential cross sections (DCS) of argon atom in the energy range from 40 to 300 eV are presented. DCS have been measured in the crossed beam arrangement of the electron spectrometer with an energy resolution of 0.5 eV and angular resolution of 1.5∘ in the range of scattering angles from 20∘ to 126∘. Both angular behaviour and energy dependence of DCS are obtained in a separate sets of experiments, while the absolute scale is achieved via relative flow method, using helium as a reference gas. All data is corrected for the energy transmission function, changes of primary electron beam current and target pressure, and effective path length (volume correction). DCSs are calculated in relativistic framework by expressing the Mott’s cross sections in partial wave expansion. Our results are compared with other available data

The role of some collisional processes in AGNs: Rate coefficients needed for modeling

International audienceThe importance of some atom hydrogen collisions in AGN has been investigated. The results are useful for better estimation of the hydrogen Balmer lines fluxes, which usage for effective temperature diagnostics in astrophysical plasma is limited by errors from the line formation models. The data could be also useful for modeling cooler and denser parts of AGN BLR clouds, as well as for the investigation of Rydberg states of hydrogen and for the study of their influence during the cosmological recombination epoch. The results of the present work suggest that the investigated processes are of interest for the research and modeling of such media

Elastic electron scattering cross sections for triethyl phosphate molecule at intermediate electron energies from 50 eV to 250 eV

We present a combined experimental and theoretical study of the electron elastic differential cross sections of triethyl phosphate molecule (C2H5)3PO4 (TEP). The experimental setup based on a crossed beam technique comprising of an electron gun, a single capillary gas needle and a detection system with a channeltron was used to measure differential cross sections. The absolute scale for the cross sections is obtained by relative-flow method using argon gas as a reference. For the interpretation of the measured data we applied the partial expansion method to calculate the elastic cross sections of TEP. We found excellent agreement between the shapes of measured and calculated data

Absolute differential cross-sections for elastic electron scattering from sevoflurane molecule in the energy range from 50–300 ev

We report the results of the measurements and calculations of the absolute differential elastic electron scattering cross-sections (DCSs) from sevoflurane molecule (C4H3F7O). The experimental absolute DCSs for elastic electron scattering were obtained for the incident electron energies from 50 eV to 300 eV, and for scattering angles from 25◦ to 125◦ using a crossed electron/target beams setup and the relative flow technique for calibration to the absolute scale. For the calculations, we have used the IAM-SCAR+I method (independent atom model (IAM) applying the screened additivity rule (SCAR) with interference terms included (I)). The molecular cross-sections were obtained from the atomic data by using the SCAR procedure, incorporating interference term corrections, by summing all the relevant atomic amplitudes, including the phase coefficients. In this approach, we obtain the molecular differential scattering cross-section (DCS), which, integrated over the scattered electron angular range, gives the integral scattering cross-section (ICS). Calculated cross-sections agree very well with experimental results, in the whole energy and angular range