Negative ions formed in N₂/CH₄/Ar discharge – a simulation of Titan's atmosphere chemistry

The formation of negative ions produced in a negative point-to-plane corona discharge fed by a Ar/N2//CH4/ gas mixture has been studied using mass spectrometry. The measurements were carried out in flowing regime at ambient temperature and a reduced pressure of 460 mbar. The CN ? anion has been found to be the most dominant negative ion in the discharge and is believed to be the precursor of heavier negative ions such as C3/N ? and C5/N ? . The most likely pathway for the formation of such molecular anions is H-loss dissociative electron attachment to HCN, H3/CN and H5/CN formed in the discharge. These same anions have been detected in Titan's atmosphere and the present experiments may provide some novel insights into the chemical and physical mechanisms prevalent in Titan's atmosphere and hence assist in the interpretation of results from the Cassini Huygens space mission

Absolute cross sections for dissociative electron attachment and dissociative ionization of cobalt tricarbonyl nitrosyl in the energy range from 0 eV to 140 eV

We report absolute dissociative electron attachment (DEA) and dissociative ionization (DI) cross sections for electron scattering from the focused electron beam induced deposition (FEBID) precursor Co(CO)3NO in the incident electron energy range from 0 to 140 eV. We find that DEA leads mainly to single carbonyl loss with a maximum cross section of 4.1 × 10−16 cm2, while fragmentation through DI results mainly in the formation of the bare metal cation Co+ with a maximum cross section close to 4.6 × 10−16 cm2 at 70 eV. Though DEA proceeds in a narrow incident electron energy range, this energy range is found to overlap significantly with the expected energy distribution of secondary electrons (SEs) produced in FEBID. The DI process, on the other hand, is operative over a much wider energy range, but the overlap with the expected SE energy distribution, though significant, is found to be mainly in the threshold region of the individual DI processes

Organic chemistry of NH₃ and HCN induced by an atmospheric abnormal glow discharge in N₂-CH₄ mixtures

The formation of the chemical products produced in an atmospheric glow discharge fed by a N2-CH4 gas mixture has been studied using Fourier Transform InfraRed (FTIR) and Optical Emission Spectrometry (OES). The measurements were carried out in a flowing regime at ambient temperature and pressure with CH4 concentrations ranging from 0.5% to 2%. In the recorded emission spectra the lines of the second positive system CN system and the first negative system of N2 were found to be the most intensive but atomic Hα, Hβ, and C (247 nm) lines were also observed. FTIR-measurements revealed HCN and NH3 to be the major products of the plasma with traces of C2H2. These same molecules have been detected in Titan's atmosphere and the present experiments may provide some novel insights into the chemical and physical mechanisms prevalent in Titan's atmosphere with these smaller species believed to be the precursors of heavier organic species in Titan's atmosphere and on its surface

Adaptive Equipment at Home: increased health literacy in patient resources

Adaptive Equipment at Home is an educational health-literate patient resource designed for older adults with limited health literacy, with a focus on improving the understanding of adaptive equipment in an accessible way. Many patient resources are not health literate, leading to decreased functional independence, quality of life, and safety, especially in the older adult population. Adaptive Equipment at Home follows health literacy guidelines founded upon evidence-based research while applying the core principles from andragogy theory and the rehabilitative frame of reference. The ultimate goal of Adaptive Equipment at Home is to increase functional independence in older adults while improving the policies regarding health literacy in patient resources in healthcare facilities

Absolute ozone densities in a radio-frequency driven atmospheric pressure plasma using two-beam UV-LED absorption spectroscopy and numerical simulations

International audienceThe efficient generation of reactive oxygen species (ROS) in cold atmospheric pressure plasma jets (APPJs) is an increasingly important topic, e.g. for the treatment of temperature sensitive biological samples in the field of plasma medicine. A 13.56 MHz radio-frequency (rf) driven APPJ device operated with helium feed gas and small admixtures of oxygen (up to 1%), generating a homogeneous glow-mode plasma at low gas temperatures, was investigated. Absolute densities of ozone, one of the most prominent ROS, were measured across the 11 mm wide discharge channel by means of broadband absorption spectroscopy using the Hartley band centred at lambda = 255 nm. A two-beam setup with a reference beam in Mach--Zehnder configuration is employed for improved signal-to-noise ratio allowing high-sensitivity measurements in the investigated single-pass weak-absorbance regime. The results are correlated to gas temperature measurements, deduced from the rotational temperature of the N2 (C 3 {{{\Pi }}}u \to B 3 {{{\Pi }}}g , upsilo = 0 \to 2) optical emission from introduced air impurities. The observed opposing trends of both quantities as a function of rf power input and oxygen admixture are analysed and explained in terms of a zero-dimensional plasma-chemical kinetics simulation. It is found that the gas temperature as well as the densities of O and O2(b{}1{{{Sigma }}}g ) influence the absolute O3 densities when the rf power is varied

The Influence of CO2 Admixtures on Process in Titan's Atmospheric Chemistry

The exploration of planetary atmosphere is being advanced by the exciting results of the Cassin-Huygens mission to Titan. The complex chemistry revealed in such atmospheres leading to the synthesis of bigger molecules is providing new insights into our understanding of how life on Earth developed. In our experiments Titan's atmosphere is simulated in a glow discharge formed from a mixture of N2:CH4:CO2 gas. Samples of the discharge gas were analysed by GC-MS and FTIR. The major products identified in spectra were: hydrogen cyanide, acetylene and acetonitrile. The same compounds were detected in the FTIR: hydrogen cyanide, acetylene and ammonia. Whilst many of these compounds have been predicted and/or observed in the Titan atmosphere, the present plasma experiments provide evidence of both the chemical complexity of Titan atmospheric processes and the mechanisms by which larger species grow prior to form the dust that should cover much of the Titan's surface

Supplementary information for: "Dissociative electron attachment and electronic excitation in Fe(CO)(5)"

Geometry of Fe(CO)5 (xyz coordinates); Excited states: Spin and dipole allowed transitions; Spin allowed, dipole forbidden transitions; Singlet-triplet transitions.The supplementary information for: Allan, M., Lacko, M., Papp, P., Matejcik, S., Zlatar, M., Fabrikant, I. I., Kocisek, J.,& Fedor, J. (2018). Dissociative electron attachment and electronic excitation in Fe(CO)(5). Physical Chemistry Chemical Physics, Royal Soc Chemistry, Cambridge., 20(17), 11692-11701. [https://doi.org/10.1039/c8cp01387j]The published version of the article: [https://cer.ihtm.bg.ac.rs/handle/123456789/2312]The peer-reviewed version of the article: [http://cer.ihtm.bg.ac.rs/handle/123456789/2659

Modelling of the effect of ELMs on fuel retention at the bulk W divertor of JET

Effect of ELMs on fuel retention at the bulk W target of JET ITER-Like Wall was studied with multi-scale calculations. Plasma input parameters were taken from ELMy H-mode plasma experiment. The energetic intra-ELM fuel particles get implanted and create near-surface defects up to depths of few tens of nm, which act as the main fuel trapping sites during ELMs. Clustering of implantation-induced vacancies were found to take place. The incoming flux of inter-ELM plasma particles increases the different filling levels of trapped fuel in defects. The temperature increase of the W target during the pulse increases the fuel detrapping rate. The inter-ELM fuel particle flux refills the partially emptied trapping sites and fills new sites. This leads to a competing effect on the retention and release rates of the implanted particles. At high temperatures the main retention appeared in larger vacancy clusters due to increased clustering rate