Electron cyclotron resonance ion source plasma characterization by energy dispersive x-ray imaging

Pinhole and CCD based quasi-optical x-ray imaging technique was applied to investigate the plasma of an electron cyclotron resonance ion source (ECRIS). Spectrally integrated and energy resolved images were taken from an axial perspective. The comparison of integrated images taken of argon plasma highlights the structural changes affected by some ECRIS setting parameters, like strength of the axial magnetic confinement, RF frequency and microwave power. Photon counting analysis gives precise intensity distribution of the x-ray emitted by the argon plasma and by the plasma chamber walls. This advanced technique points out that the spatial positions of the electron losses are strongly determined by the kinetic energy of the electrons themselves to be lost and also shows evidences how strongly the plasma distribution is affected by slight changes in the RF frequency. © 2017 IOP Publishing Ltd

Blocking effect on transmission of Ne7+ ions through nanocapillaries

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Conductivity mechanism probed by ion transmission through nanocapillaries during the discharging process

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Preliminary studies of creation of gold nanoparticles on titanium surface towards biomedical applications

This paper is devoted to present the results of creation of gold nanoparticles on titanium surface. We focused on the problem how to create gold nanoparticles on the titanium surface with defined particle size and distribution, which could be interesting for several applications (e.g. providing well-defined substrates for biomedical research, etc.). To do that the sample is affected by the complex physical rout of gold nanoparticles formation: by gold ion implantation, thin Au layer deposition and thermal annealing. The effect of the technology, influence on the surface structure and its parameters were investigated by the X-ray diffraction, Scanning Electron and Atomic Force Microscopy, as well as by Secondary Neutral Mass Spectrometry methods

A systematic mid-infrared spectroscopic study of thermally processed SO 2 ices

We have performed a systematic study of the mid-infrared absorption spectroscopy of SO 2 ices under thermal conditions relevant to astrochemistry

Investigation of silver nanoparticles on titanium surface created by ion implantation technology

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Bombardment of CO ice by cosmic rays: I. Experimental insights into the microphysics of molecule destruction and sputtering

We present a dedicated experimental study of microscopic mechanisms controlling radiolysis and sputtering of astrophysical ices due to their bombardment by cosmic ray ions. Such ions are slowed down due to inelastic collisions with bound electrons, resulting in ionization and excitation of ice molecules. In experiments on CO ice irradiation, we show that the relative contribution of these two mechanisms of energy loss to molecule destruction and sputtering can be probed by selecting ion energies near the peak of the electronic stopping power. We have observed a significant asymmetry, both in the destruction cross section and the sputtering yield, for pairs of ion energies corresponding to same values of the stopping power on either side of the peak. This implies that the stopping power does not solely control these processes, as usually assumed in the literature. Our results suggest that electronic excitations represent a significantly more efficient channel for radiolysis and, possibly, also for sputtering of CO ice. We also show that the charge state of incident ions as well as the rate for CO$^+$ production in the ice have negligible effect on these processes.Comment: Accepted for publication in Ap

Energetic Electron Irradiations of Amorphous and Crystalline Sulphur-Bearing Astrochemical Ices

Laboratory experiments have confirmed that the radiolytic decay rate of astrochemical ice analogues is dependent upon the solid phase of the target ice, with some crystalline molecular ices being more radio-resistant than their amorphous counterparts. The degree of radio-resistance exhibited by crystalline ice phases is dependent upon the nature, strength, and extent of the intermolecular interactions that characterise their solid structure. For example, it has been shown that crystalline CH3OH decays at a significantly slower rate when irradiated by 2 keV electrons at 20 K than does the amorphous phase due to the stabilising effect imparted by the presence of an extensive array of strong hydrogen bonds. These results have important consequences for the astrochemistry of interstellar ices and outer Solar System bodies, as they imply that the chemical products arising from the irradiation of amorphous ices (which may include prebiotic molecules relevant to biology) should be more abundant than those arising from similar irradiations of crystalline phases. In this present study, we have extended our work on this subject by performing comparative energetic electron irradiations of the amorphous and crystalline phases of the sulphur-bearing molecules H2S and SO2 at 20 K. We have found evidence for phase-dependent chemistry in both these species, with the radiation-induced exponential decay of amorphous H2S being more rapid than that of the crystalline phase, similar to the effect that has been previously observed for CH3OH. For SO2, two fluence regimes are apparent: a low-fluence regime in which the crystalline ice exhibits a rapid exponential decay while the amorphous ice possibly resists decay, and a high-fluence regime in which both phases undergo slow exponential-like decays. We have discussed our results in the contexts of interstellar and Solar System ice astrochemistry and the formation of sulphur allotropes and residues in these settings