Gases Ne Research Articles

Atomistic Insights into Carbon Dioxide Sequestration in Natural Gas Hydrates in the Presence of Mixture of Flue and Noble Gases

AbstractThe exchange of carbon dioxide with methane in natural gas hydrates (NGHs) is one of the sustainable approaches for the sequestration of carbon dioxide in NGHs. However, the formation of mixed CH4─CO2 hydrates during CH4─CO2 exchange in NGHs reduces the rate of CH4─CO2 exchange in NGHs. It is reported that molecular level insights into CH4─CO2 exchange in NGHs using quaternary‐gas systems of CH4, CO2, and a mixture of flue (H2S and N2) and noble (Ne, Ar, Kr, and Xe) gases in heterogeneous medium using molecular dynamics simulation techniques. The sequestration of gases other than CH4 in the new hydrate cages besides the interface is the highest in CO2:H2S:Ar (2:1:1) system among all the reported quaternary‐gas systems. The results show that Ar enhances CO2 sequestration in NGHs in the presence of H2S rather than N2. The hydrate growth occurs due to the formation of dual hydrate cages. Among the methane molecules released from the hydrate slab in a binary‐gas (CH4─CO2) system, > 60 % of the released methane molecules reform new cages beside the interface. On the other hand, only ≈ 50 % of the released methane molecules reform new hydrate cages besides the interface in CO2:H2S:Ar (2:1:1) system.

The thermal equation of state of xenon: Implications for noble gas incorporation in serpentine minerals and their transport to depth

Isotopic signatures of heavy noble gases in the Earth's mantle contain a major component recycled by subduction. The experimental and field studies reported in the literature show increasing evidence that serpentine minerals can hold large quantities of noble gases, potentially serving as their primary vectors to depth. However, at present, their retention mechanism in these minerals is not fully understood. Additionally, noble gas solubilities from field and experimental studies show large differences in terms of elemental concentrations. Here, we performed crystal chemical modeling to evaluate the incorporation mechanism of noble gases and their solubilities in serpentine minerals along subduction zone geotherms. To this end, we determined the thermal equation of state of xenon using in situ X-ray diffraction and absorption up to 60 GPa and 728 K. In this range, the xenon equation of state is well-adjusted using the Mie-Grüneisen-Debye formalism with relevant fitting parameters. We show that the experimentally observed solubility trend, which follows the order Ne < He < Ar < Kr < Xe, can be explained by the incorporation of noble gases at two distinct crystallographic sites. The light noble gases He and Ne are most likely retained at the van der Waals hydrogen-oxygen bond position between the layers, while the heavy and larger noble gases enter the voids between the six-membered SiO4 rings. It should be noted that octahedral sites can potentially host xenon, but cannot accommodate argon and krypton. Indeed, this would require unrealistic flexibility of the crystal lattice. Our models extended to mantle wedge conditions predict decreasing solubilities, particularly for light noble gases, in agreement with observations from natural samples. Compared to the noble gas concentrations determined experimentally in serpentine, natural concentrations are much higher and very variable. Our solubility model confirms that equilibrium processes cannot explain these observations. We therefore suggest that the high and variable noble gas concentrations found in natural samples must be due to hybrid hydration processes in ultramafic rocks that involve different degrees of water activities.

Cross-calibration of quantum atomic sensors for pressure metrology

Quantum atomic sensors have shown great promise for vacuum metrology. Specifically, the density of gas particles in vacuum can be determined by measuring the collision rate between the particles and an ensemble of sensor atoms. This requires preparing the sensor atoms in a particular quantum state, observing the rate of changes of that state, and using the total collision rate coefficient for state-changing collisions to convert the rate into a corresponding density. The total collision rate coefficient can be known by various methods, including quantum scattering calculations using a computed interaction potential for the collision pair, measurements of the post-collision sensor-atom momentum recoil distribution, or empirical measurements of the collision rate at a known density. Observed discrepancies between the results of these methods call into question their accuracy. To investigate this, we study the ratio of collision rate measurements of co-located sensor atoms, 87Rb and 6Li, exposed to natural abundance versions of H2, He, N2, Ne, Ar, Kr, and Xe gases. This method does not require knowledge of the test gas density and is, therefore, free of the systematic errors inherent in efforts to introduce the test gas at a known density. Our results are systematically different at the level of 3% to 4% from recent theoretical and experiment measurements. This work demonstrates a model-free method for transferring the primacy of one atomic standard to another sensor atom and highlights the utility of sensor-atom cross-calibration experiments to check the validity of direct measurements and theoretical predictions.

Synergistic Effect of He for the Fabrication of Ne and Ar Gas-Charged Silicon Thin Films as Solid Targets for Spectroscopic Studies.

Sputtering of silicon in a He magnetron discharge (MS) has been reported as a bottom-up procedure to obtain He-charged silicon films (i.e., He nanobubbles encapsulated in a silicon matrix). The incorporation of heavier noble gases is demonstrated in this work with a synergistic effect, producing increased Ne and Ar incorporations when using He-Ne and He-Ar gas mixtures in the MS process. Microstructural and chemical characterizations are reported using ion beam analysis (IBA) and scanning and transmission electron microscopies (SEM and TEM). In addition to gas incorporation, He promotes the formation of larger nanobubbles. In the case of Ne, high-resolution X-ray photoelectron and absorption spectroscopies (XPS and XAS) are reported, with remarkable dependence of the Ne 1s photoemission and the Ne K-edge absorption on the nanobubble's size and composition. The gas (He, Ne and Ar)-charged thin films are proposed as "solid" targets for the characterization of spectroscopic properties of noble gases in a confined state without the need for cryogenics or high-pressure anvils devices. Also, their use as targets for nuclear reaction studies is foreseen.

Deuterium retention in tungsten co-deposits with neon and argon inclusions

Deuterium (D) retention in tungsten (W) co-deposited layers, in the presence of neon (Ne) and argon (Ar), was investigated using the bipolar High Power Impulse Magnetron Sputtering (BP-HiPIMS) technique. The deposited layers have a polycrystalline structure, with a preferential growth of W(110) phase. The concentration of D and noble gases (Ne and Ar) is almost constant throughout the depth of the layers. In a D2-Ar discharge, the deposited layers exhibit compressive stress, indicating that Ar is mostly incorporated into the interstitial sites of the W crystal lattice. D retention increases when Ne is added in the discharge, especially when the deposited layer is bombarded with highly energetic ions. Low energy Ne ions (below the W damaging threshold) induce compressive stress, indicating that Ne atoms occupy interstitial sites in the W crystal lattice. High energy Ne ions induce tensile stress, a sign that Ne is trapped in the grain boundaries as inert-gas-vacancy defects, leading to a grain-boundary relaxation. In the presence of Ne, the ion acceleration towards the layer from 0 V to 300 V results in an increase of the D content of about three times, from 3.2 at.% to 8.6 at.%.

Intracavity heterodyne laser interferometry. Studies of the features of optical Kerr effect in the atmosphere

The features of high-sensitivity frequency and phase measurements in a He–Ne gas laser at a wavelength of 0.63 μm are considered. The single-frequency mode of this laser with a large excess of the lasing threshold is implemented due to longitudinal mode selection using an ultra-thin nickel metal film placed in the standing field node of the cavity. With such an excess of the lasing threshold, the natural linewidth component is very small (∼10−3Hz), which was determined from the heterodyne method of measuring natural fluctuations of lasing frequency. This method can be used in combination with the multibeam intracavity interferometry for measuring phase modulation at a level of 10−9 rad Hz−1/2. To demonstrate the capabilities of the method, the electro-optical Kerr effect in air at atmospheric pressure in linearly polarized light was studied separately for extraordinary and ordinary waves. The Kerr and the Havelock constants were measured. A deviation from a purely quadratic dependence determined by the fourth power of the amplitude of a low-frequency electric field was found. A possible explanation of the detected deviation from the Kerr effect is the electrostriction.

Experimental Characterization and Simulation of a Dipole Plasma Antenna for VHF Band and Effect of Ar–Ne Gas Composition

Experimental Characterization and Simulation of a Dipole Plasma Antenna for VHF Band and Effect of Ar–Ne Gas Composition

Paticularities of radiation defect formation in ceramic barium cerate

The results of the investigations are presented on the effect of irradiation with electrons, ions of inert gases (Ne, Ar, Kr) and oxygen on the structure and properties of Nd-doped barium cerate by the methods of X-ray diffraction analysis, scanning electron and atomic force microscopy, thermal desorption spectroscopy. It is shown that the low-energy irradiation with Ne and Ar ions stimulates the blistering processes on the surface, whereas the high energy ion irradiation by Ne, Ar, Kr ions the cerate surface undergoes the following stages of the spherulite growth - nucleation, growth (view of cauliflower), formation of spherulitic crust, correspondingly. The similar structures were not observed in the case of irradiation with high-energy oxygen ions. It is noticed that the irradiation of cerates with electrons leads to the formation of nano-sized acicular structures on the surface. The radiation of lowenergy ions of inert gases led to the conversion of most of the neodymium into a tetravalent state, as has been shown, accompanied by an increase in oxygen release and a decrease in water compared to non-irradiated cerate, as well as the independence of the amount of gases from the type of ions. Based on the data on thermal desorption of water and oxygen molecules from the irradiated barium cerate it was assumed that the irradiation stimulates the oxidation to Nd4+.

Inter-laboratory re-determination of the atmospheric 22Ne/20Ne

Accurate knowledge of the Ne isotopic composition of air is essential for planetary science. While the uncertainty of the noble gas isotopic composition of air has been drastically reduced to the level of ∼0.1% in the last few years thanks to modern techniques, the most widely accepted value of the 22Ne/20Ne ratio of air (0.102 ± 0.0008, Eberhardt et al., 1965) has an uncertainty of ±0.78% (1σ). Here we present the first multi-laboratory re-determination of the atmospheric 22Ne/20Ne. An artificial, high purity mixture of 20Ne and 22Ne was prepared and the 22Ne/20Ne (0.11888 ± 0.00001, 1σ) and 20Ne/22Ne (8.4118 ± 0.0007, 1σ) determined gravimetrically. This gas was used to determine the mass fractionation of five mass spectrometers allowing the air 22Ne/20Ne to be determined (n = 234 analyses). Each laboratory sampled their own local air, used a different gas preparation system and analysis procedure as well as doing their own expansion of the high-pressure artificial Ne gas. Individual air 22Ne/20Ne determinations have uncertainties in the range of 0.01–0.08%. The overall reproducibility of the calculated 22Ne/20Ne of air between the laboratories shows no overdispersion with respect to the individual uncertainties. We report a global value for the atmospheric 22Ne/20Ne of 0.10196 ± 0.00007 (0.07%, 1σ), equivalent of 20Ne/22Ne of 9.808 ± 0.007. This is almost identical to the Eberhardt et al. (1965) value although its uncertainty shows a 12 times reduction. Our study did not verify any of the other previous determinations of atmospheric 22Ne/20Ne. This highly accurate and precise atmospheric 22Ne/20Ne value provides a new reference for atmospheric 21Ne/20Ne determinations and we recalculate (21Ne/20Ne)air of five recent determinations. While this exercise resulted in no significant change to the absolute values, it gives more confidence with respect to the correctness of (21Ne/20Ne)air. We suggest that the revised value for atmospheric 22Ne/20Ne be used routinely in all geoscience applications.

The effect of inert gases (Xe, Ar, Ne, He) on decomposition reactions of N2O, CH4 and CO2 at high pressures

In a pulsed compression reactor (PCR) experiments were done with N2O (4%mol), CH4 (1%mol) and CO2 (2%mol) diluted in the inert gases Xe, Ar, Ne and He. The mixtures were compressed up to 250 bar, reaching temperatures of up to 4000 K. At equal temperature, pressure and volume, significant differences (up to 20%) were measured in the conversion of the three species in different noble gases. The measurements with N2O decomposition showed that the reaction is the fastest in the most heavy noble gas tested. The conversion decreased as the molar mass of the noble gas decreased. Likewise, methane pyrolysis was measured to be the fastest in xenon and slowed down in accordance with the mass of the inert molecule. A reverse trend was measured for the decomposition of CO2 to CO and O⋅, which is explained by the dominant role of the reverse reaction. As a result, the CO2 data is also explained by conversion rates that are higher in heavier gases. This paper provides a first attempt to understand the observed influence of the molar mass of the inert bathing gas on the reaction rate in the high pressure domain. A theory is proposed based on a Newtonian description of reactant activation by the inert bathing gas.

A Critical Analysis of Target Ionization and Projectile Electron Loss in Neutral– and Ion–Atom Collisions

Electron removal (target ionization and/or projectile electron loss) in neutral–atom collisions is theoretically studied for the impact of H0, He0 and He+ beams on noble gases (He, Ne and Ar). These reactions are investigated theoretically within the Continuum Distorted Wave-Eikonal Initial State model. New features have been included in the theoretical model: (i) a scaled projectile charge depending on its velocity and charge, (ii) a dynamic projectile-effective-charge depending on the momentum transfer, and (iii) a dynamic target-effective-charge depending on the kinematics of the emitted electron. The energy and angular spectra of emitted electrons from the target and from the projectile are calculated and compared with the available experimental data. Also, the influence of each one of the corrections on the resulting spectra will be studied.

Geochemical evidence for a lithospheric origin of the Comoros Archipelago (Indian Ocean) as revealed by ultramafic mantle xenoliths from La Grille volcano

Petrology and fluid inclusions (FI) geochemistry are increasingly used in tandem to constrain the compositional features and evolution of the lithospheric mantle. In this study, we combine petrography and mineral chemistry with analyses of noble gases (He, Ne and Ar) and CO2 in olivine, orthopyroxene- and clinopyroxene-hosted FI, as well as radiogenic isotope (Sr-Nd-Pb) systematics of ultramafic xenoliths collected at La Grille volcano in Grande Comore Island, aiming at better characterizing one of the most enigmatic and controversial portions of the western Indian Ocean lithospheric mantle. Xenoliths have been divided in three groups on the basis of their textural features: Group 1 (Opx-bearing), Group 2 (Opx-free) and Group 3 (Cumulate). Overall, petrographic observations and mineral phase compositions indicate that the sampled lithospheric portion experienced variable degrees of melting (from 5% to 35%), recorded by Group 1 most refractory harzburgites and lherzolites, as well as modal metasomatic processes as evidenced by the crystallization of cpx at the expense of opx in Group 1 fertile lherzolites and wehrlite and by Group 2 xenoliths. Crystallization of slightly oversaturated basic silicate melts seems also to have occurred, as shown by Group 3 xenoliths. A positive trend between temperature and ƒO2 is evident, with Group 2 and 3 xenoliths testifying for hotter and more oxidised conditions than Group 1. The variability of the 4He/40Ar* ratio (0.02–0.39) in Group 1, significantly below typical values of a fertile mantle (4He/40Ar* = 1–5), can be explained by the variable degrees of partial melting coupled to metasomatic enrichment that may account for modifying 4He/40Ar*, as also indicated by the mineral composition. He-Ar-CO2 relationships support the presence of a metasomatic CO2-rich process post-dating the melt extraction and the cumulate formation. The air-corrected 3He/4He isotopic ratios (6.30 to 7.36 Ra) are intermediate between the MORB mantle signature (8 ± 1Ra) and the SCLM (6.1 ± 0.9 Ra). The Ne and Ar isotopic signatures (20Ne/22Ne, 21/Ne/22Ne and 40Ar/36Ar) are consistent with mixing between an air-derived component and a MORB-like mantle, supporting the hypothesis for a lithospheric origin of the Comoros magmas, and arguing against any deep mantle plume-related contribution. This is also corroborated by combining Ne with He isotopes, showing that La Grille ultramafic xenoliths are far from the typical plume-type compositions. Sr-Nd-Pb isotope systematics in opx and cpx from La Grille additionally support a MORB-type signature for the lithospheric mantle beneath the area.

Simultaneous observation of noble gases and highly charged ions in an electron beam ion trap for accurate wavelength calibration of optical transitions

Spectral lines of buffer noble gases injected into an electron beam ion trap (EBIT) have recently been used as a reference to aid accurate determination of the wavelengths of optical transitions of highly charged ions (HCIs). Simultaneous observation of emission lines of HCIs along with those of neutral atoms or singly charged ions represents a reliable method for wavelength calibration that suppresses systematic uncertainties. Here, we present visible and infrared emission spectra of buffer Ne and Ar gases in an EBIT and briefly review the buffer gas calibration method. The experimental conditions required for implementing the calibration method are discussed by investigating the dependence of the emission spectra of mixtures of HCIs and noble gases on electron beam’s parameters and gas pressure.

Light noble gases in 11 achondrites: Cosmic ray exposure ages, gas retention ages, and preatmospheric sizes

AbstractWe report light noble gas (He, Ne, and Ar) concentrations and isotopic ratios in 11 achondrites, Tafassasset (unclassified primitive achondrite), Northwest Africa (NWA) 12934 (angrite), NWA 12573 (brachinite), Jiddat al Harasis (JaH) 809 (ureilite), NWA 11562 (ungrouped achondrite), four lodranites (NWA 11901, NWA 7474, NWA 6685, and NWA 6484), NWA 2871 (acapulcoite), and Sahara 02029 (winonaite), most of which have not been previously studied for noble gases. We discuss their noble gas isotopic composition, determine their cosmogenic nuclide content, and systematically calculate their cosmic ray exposure (CRE) and gas retention ages. In addition, we estimate their preatmospheric radii and preatmospheric masses based on the shielding parameter (22Ne/21Ne)cos. None of the studied meteorites shows evidence of contribution from solar cosmic rays (SCRs). JaH 809 and NWA 12934 show evidence of 3He diffusive losses of &gt;90% and 40%, respectively. The winonaite Sahara 02029 has lost most of its noble gases, either during or before analysis. The average CRE age of Tafassasset of ~49 Ma is lower than that reported by Patzer et al. (2003), but is consistent with it within the uncertainties; this confirms that Tafassasset and CR chondrites are not source paired, CR chondrites having CRE ages from 1 to 25 Ma (Herzog &amp; Caffee, 2014). The ureilite JaH 809 has a CRE age of ~5.4 Ma, which falls into the typical range of exposure ages for ureilites; the angrite NWA 12934 has a CRE age of ~49 Ma, which is within the main range of exposure ages reported for angrites (0.2–56 Ma). We calculate a CRE age of ~2.4 Ma for the brachinite NWA 12573, which falls into a possible “cluster” in the brachinite CRE age histogram around ~3 Ma. Three lodranites (NWA 11901, NWA 7474, and NWA 6685) have CRE ages higher than the average CRE ages of lodranites measured so far, NWA 11901 and NWA 6685 having CRE ages far higher than the CRE age already reported by Li et al. (2019) on NWA 8118. The measured 40K‐40Ar gas retention ages fit well into established systematics. The gas retention age of Tafassasset is consistent, within respective uncertainties, with that previously calculated by Patzer et al. (2003). Our study indicates that Tafassasset originates from a meteoroid with a preatmospheric radius of ~20 cm, however discordant with the radius of ~85 cm inferred in a previous study (Patzer et al., 2003).

Total neutron emission from deuteron fusion and plasma pinch compression in a medium-sized plasma focus operating with D2 and D2 + Ne gas mixtures—Experimental results

Newly obtained results on hot and dense deuterium and deuterium-neon plasma compression in a z-pinch electrical discharge configuration are presented. The investigated plasma was generated and compressed using 269 high-current discharges in a medium-sized (dense) plasma focus device. The experimental chamber of the device was filled with deuterium and deuterium-neon gas mixtures under constant total mass/density conditions. Magnetic and electric probes, beryllium neutron activation counter, and high-speed four-frame vacuum ultraviolet/soft x-ray pinhole camera were used to study the plasma dynamics and radiation emission. The results obtained experimentally for the first time confirmed clearly a decrease in the minimum radius of plasma columns with an increase in initial neon fraction. Simultaneously, a decrease in the total neutron emission from deuteron fusion was found. The observed plasma/discharge evolution revealed that the classical description of plasma-focus discharges can be approximately correct up to the moment of maximum compression. Including, existence of quasi-equilibrium plasma compression is probable. It is also possible that the homogeneity of plasma columns during the slow compression phase and maximum compression moment increases with the increase in initial neon fraction. The effect of higher stabilization (repeatability) of discharges was confirmed, for higher initial neon fractions. The dependency of the total neutron emission yield on the parameters describing the full discharge dynamics and the maximum discharge voltage was confirmed. The existence of this type of dependency, for a minimum pinch radius is also possible. In contrast, there was little dependency to the total discharge current parameters measured in the collector area.

Ancient atmospheric noble gases preserved in post-impact hydrothermal minerals of the 200 Ma-old Rochechouart impact structure, France

The evolution of Earth's atmosphere over billions of years provides important constraints on the geological history of our planet. However, major challenges in studying this have been finding samples in which ancient atmospheric signals are reliably preserved and precisely determining the age of the trapped atmosphere. Hydrothermal minerals can preserve fluid inclusions that formed from air-saturated waters. However, the use of hydrothermal minerals as paleo-atmospheric proxies is often limited by contamination by deeply-sourced crustal gases (e.g., radiogenic noble gases) and the difficulty of providing precise age constraints on the crystallization of the hydrothermal minerals.In this study, we tested the hypothesis that meteorite impact craters could provide an untapped archive of atmospheric evolution by investigating noble gases (Ne, Ar, Kr and Xe) contained in fluid inclusions within post-impact hydrothermal minerals from the Rochechouart impact structure (France). Impact craters can be dated using a variety of methods and because meteorite impacts cause localized fracturing of country rocks and the development of minor thermal anomalies, they are often associated with short-lived (up to a few Ma, depending on the size of the crater) and shallow hydrothermal systems dominated by surface-derived hydrothermal fluids.We found that the elemental ratios of noble gases in quartz from Rochechouart are close to the elemental ratios of modern Air. Furthermore, most noble gas isotope ratios are close to modern atmosphere, except for rare deviations caused by radiogenic ingrowth, nucleogenic effects and/or minor mass fractionation. After a minor correction for post-entrapment decay of 40K, an upper limit for the 40Ar/36Ar ratio of the ∼200 Ma atmospheric component trapped in Rochechouart quartz is determined as 292.7 ± 3.6 (2σ s.d.), which is significantly lower than the modern value of 298.6 ± 0.3. A Mesozoic 40Ar/36Ar ratio lower than 292.7 ± 3.6 is in line with the existing paleo-atmospheric dataset and existing models of the temporal evolution of the atmospheric 40Ar/36Ar ratio and conclusively proves the preservation of an ancient atmospheric component in rocks from Rochechouart. Given that meteorite impacts have occurred throughout the entire Earth's history they might collectively provide a unique, yet unexplored, repository of the atmospheric evolution. The same approach might also be applicable to investigating the atmospheric evolution of other terrestrial planets.

Visible and Ultraviolet Plasma Lines of the He–Ne Gas Laser

A study of helium–neon laser plasma lines was done using a double grating spectrometer and a helium-neon laser with an emission wavelength of 632.8 nm (15 802 cm−1). The absolute wavenumber, measured to within [Formula: see text]0.2 cm−1, and wavelength of each plasma line are presented, along with intensity and shift relative to the main laser line. Several of the measured lines have not been reported in the literature and are observed at shifts between 0 and 1500 cm−1 from the laser line, a spectral region commonly probed by optical Raman scattering experiments. Accounting for the possibility of second-order diffraction permitted many previously unassigned lines to be attributed to known neon electronic transitions with wavelengths in the ultraviolet region of the electromagnetic spectrum.

Modeling of Inert Gas Sensors Using First Principles Methods

The detection of inert gases is difficult due to their inactive nature what makes preparation of the applicable gas sensor a challenging task. This work reports comprehensive first principles investigations to design inert gas sensors. Graphene (Gr) sheets decorated with palladium clusters Pd <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">n</sub> (n = 2-6) were optimized after which adsorption of inert gases He, Ne, Ar, Kr, Xe and Rn was carried out using density functional theory (DFT) based formalism. The reactivity of the sensors comprising of Pd cluster-decorated-defected-graphene is significantly higher than that of the sensor with bare and defect free graphene sheet. The adsorption caused redistribution of the electronic structure which provides basis for sensing of the adsorbate. The gas sensor Pd <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> -Gr exhibited good sensitivity towards neon and xenon while Pd <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> -Gr appeared more effective in the detection of krypton gas. Helium is appropriately detected by Pd <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</sub> -Gr sensor and Pd <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">5</sub> -Gr sensor is found capable of sensing radon and argon gases. Pd <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">6</sub> -Gr sensor is not a favorable sensor for sensing of the inert gases. The findings of this work are beneficial for fabrication of inert gas sensors for small and industrial scale applications.

Flying characterization of colliding partners by hyperfine splitting frequency of neutral paramagnetic atoms.

The pseudopotentials and dispersion potentials are applied to a theoretical study of the hyperfine splitting frequencies of the ground-state paramagnetic hydrogen (H) and alkali-metal (Li, Na, K, Rb, and Cs) atoms in noble gases (He, Ne, Ar, Kr, and Xe). Using classical turning points for statistical averages, we find that numerical calculations based on second-order perturbation theory fit the measured frequency shifts well over a wide temperature range. The characteristic energy, pseudopotential height, and electric-dipole polarizability allow us to consistently determine the van der Waals radii and electron scattering lengths of noble-gas atoms. This study shows that the hyperfine splitting frequency of alkali-metal atoms is a good measure for investigating colliding partners.

Investigating noble gases and nitrogen in Zag (H3-6) and ALH 77216 (L3.7–3.9): The ordinary chondrites with solar type neon and argon

Concentrations and isotopic compositions of noble gases (He, Ne, Ar, Kr, and Xe) and nitrogen in two ordinary chondrites (OCs), Zag (H3-6) and ALH 77216 (L3.7–3.9), are presented. The aim of the study is to examine the cosmic ray exposure history, radiogenic ages and isotopic signatures of trapped gases in them. The results of stepwise heating analyses indicate that light noble gases (He and Ne) are mixture of trapped and cosmic ray produced components. Neon isotopes are enriched from solar wind (SW), while shows a trend towards galactic cosmic ray (GCR) region in both the meteorites. Phase-Q neon is not observed in any of the meteorite. The heavy noble gases Ar, Kr and Xe indicate mixture of Q-HL-SW and cosmogenic. Elemental ratios of trapped 36Ar, 84Kr and 132Xe indicate that noble gases in Zag and ALH 77216 are mixtures of the three components Q, HL and SW. The cosmic-ray exposure (CRE) ages calculated from neon for Zag and ALH 77216 are 5.6 ± 0.3 Ma and 28.5 ± 0.4 Ma, respectively. These ages are within the range typically observed for the respective meteorite types of OCs. Nitrogen isotopes indicate presence of multiple components in both the chondrites. Isotopic signature of trapped nitrogen in both the chondrites is distinct from that of SW, Q and HL, indicating additional source of nitrogen in the meteorites.