Oxygen Emission Intensity Research Articles

Morphology of Traveling Wave Disturbances Recorded in Eastern Siberia in 630 nm Atomic Oxygen Emission

Our paper presents the results of investigating wave structures detected in 630 nm atomic oxygen emission intensity (airglow height is ~180–300 km). The study employs data from a wide-angle optical system installed at the Geophysical Observatory of the ISTP SB RAS (51°48′ N, 103°04′ E). It describes the algorithm to identify wave disturbances and determine their main parameters in the optical system images. The results obtained due to automatic processing of 2014–2021 data archives are presented. The most probable values of the wave disturbances propagation velocity are about 80 m/s. The horizontal wavelengths and periods are in the range of ~30–400 km and 60–120 min, respectively. The predominant direction of disturbances propagation is to the southwest. The received data of optical and radio observations are compared. We found both similarities and differences in the wavelike structures direction, which are to be investigated in the future.

Stellar imaging coronagraph and exoplanet coronal spectrometer: two additional instruments for exoplanet exploration onboard the WSO-UV 1.7-m orbital telescope

The World Space Observatory for Ultraviolet (WSO-UV) is an orbital optical telescope with a 1.7-m diameter primary mirror currently under development. The WSO-UV is aimed to operate in the 115- to 310-nm UV spectral range. Its two major science instruments are UV spectrographs and UV imaging field cameras with filter wheels. The WSO-UV project is currently in the implementation phase, with a tentative launch date in 2023. As designed, the telescope field of view in the focal plane is not fully occupied by instruments. Recently, two additional instruments devoted to exoplanets have been proposed for WSO-UV, which are the focus of this paper. UVSPEX, a UV-spectrograph for exoplanets, aims to determine atomic hydrogen and oxygen abundance in the exospheres of terrestrial exoplanets. The spectral range is 115 to 130 nm, which enables simultaneous measurement of hydrogen and oxygen emission intensities during an exoplanet transit. A study of exosphere transit photometric curves can help differentiate among different types of rocky planets. The exospheric temperature of an Earth-like planet is much higher than that of a Venus-like planet because of the low mixing ratio of the dominant coolant (CO2) in the upper atmosphere of the former, which causes a large difference in transit depth at the oxygen emission line. Thus, whether the terrestrial exoplanet is Earth-like, Venus-like, or other can be determined. A Stellar Coronagraph for Exoplanet Direct Imaging (SCEDI) is aimed to directly detect the starlight reflected from exoplanets orbiting their parent stars or from the stellar vicinity including circumstellar disks, dust, and clumps. SCEDI will create an achromatic (optimized to 420- to 700-nm wavelength range), high-contrast stellocentric coronagraphic image of a circumstellar vicinity. The two instruments, such as UVSPEX and SCEDI, share common power and control modules. The present communication outlines the science goals of both proposed instruments and explains some of their engineering features.

The Methylene Blue Self-aggregation in Water/Organic Solvent Mixtures: Relationship Between Solvatochromic Properties and Singlet Oxygen Production

In this work is presented a spectrophotometry investigation focused on the solvatochromic effects upon Methylene Blue (MB). Measurements were carried out in four different water/organic solvent mixtures: low polarity protic solvent (ethanol), polar non-protic solvent (acetonitrile), highly polar protic solvent (glycerol), and non-polar solvent (dioxane). The results showed that the photophysical behavior of MB is highly affected by self-aggregates formation at 80% of water/organic solvent blends. Besides polarity, the protic character and the coordinating properties of the solvent molecules are the key parameters for its photophysical behavior, since the sulfur atom of the cationic structure can act as a coordination center due to its Lewis acid character. In fact, water and acetonitrile coordinating properties have proved to be important to determine MB interactions intensity and its spectroscopic properties as singlet oxygen emission. It was observed that an increase of the amount of the organic solvent resulted in an enhancement of the singlet oxygen emission intensity. The presence of the water increases the dielectric constant of the medium and favors the self-aggregation process. Besides, the water molecules can act as a quencher and it decreases the quantum yield of the fluorescence of MB. DOI: http://dx.doi.org/10.17807/orbital.v9i4.996

Diagnostics of an AC driven atmospheric pressure non-thermal plasma jet and its use for radially directed jet array

An alternating current atmospheric pressure plasma jet is generated with noble gas or noble gas/oxygen admixture as working gas. A “core plasma filament” is observed at the center of the dielectric tube and extends to the plasma jet at higher peak-to-peak voltages. This type of plasma jet is believed to be of the same nature with the reported plasma bullet driven by pulsed DC power sources. Double current probes are used to assess the speed of the plasma bullet and show that the speed is around 104–105 m/s. The time dependence of the downstream bullet speed is attributed to the gas heating and in turn the increase of the reduced electric field E/N. Optical emission spectra show the dependence of helium and oxygen emission intensities on the concentration of oxygen additive in the carrier gas, with peak values found at 0.5% O2. Multiple radial jets are realized on dielectric tubes of different sizes. As a case study, one of these multi-jet devices is used to treat B. aureus on the inner surface of a plastic beaker and is shown to be more effective than a single jet.

Phase discrimination of uranium oxides using laser-induced breakdown spectroscopy

Nuclear forensics goals for characterizing samples of interest include qualitative and quantitative analysis of major and trace elements, isotopic analysis, phase identification, and physical analysis. These samples may include uranium oxides UO2, U3O8, and UO3, which play an important role in the front end of the nuclear fuel cycle, from mining to fuel fabrication. The focus of this study is to compare the ratios of the intensities of uranium and oxygen emission lines which can be used to distinguish between different uranium oxide materials using Laser-Induced Breakdown Spectroscopy (LIBS). Measurements at varying laser powers were made under an argon atmosphere at 585Torr to ensure the oxygen emission intensity was originating from the sample, and not from the atmosphere. Fifteen uranium emission lines were used to compare experimental results with theoretical calculations in order to determine the plasma conditions. Using a laser energy of 26mJ, the uranium lines 591.539 and 682.692nm provide the highest degree of discrimination between the uranium oxides. The study presented here suggests that LIBS is useful for discriminating uranium oxide phases, UO2, U3O8, and UO3.

Study of Hydrogen and Oxygen and Its Reaction With Host Elements in Sandstone by Laser-Induced Breakdown Spectroscopy (LIBS)

A study of hydrogen and oxygen and its reaction with host elements in a sandstone has been done by laser-induced breakdown spectroscopy (LIBS). The sandstone was irradiated by Nd-YAG laser (1064 nm, 7 ns) with varied energy of 60 mJ till 140 mJ in surrounding air gas pressure of 1 atm and produced plasma. The emission intensities of hydrogen H I 656.2 nm and oxygen O I 777.2 nm in the plasma were captured by HR 2500+ spectrometer and displayed in intensity as a function of wavelength. The data show that the emission intensities of hydrogen and oxygen increase with increasing laser energy at a gradient of 5.4 and 11.8 respectively every increasing laser energy of 20 mJ. To characterize the reaction process between hydrogen and oxygen with the host elements of the sandstone, a 0.2 ml demineralized water was dropped on the sandstone surface and was analyzed as a function of delay time reaction and temperature. The data show that the oxidation reaction between host elements and oxygen occurred after 25 minutes that the oxygen emission intensity increases and the hydrogen emission intensity decreases. Another data also show that the increasing temperature of sandstone until 80 C increased intermolecular bond between oxygen and host element and dehydrogenation took place after reaching this temperature

Characterization of a Plasma Jet Produced by Spark Discharges in Argon Air Mixtures at Atmospheric Pressure

A stark difference in the electrical, optical and thermal properties of an atmospheric pressure plasma jet source exploiting spark discharges in a gas stream was reported when argon is used instead of air in the flow. Electrical probe results are discussed together with optical ones in order to investigate the discharge properties and the temporal structure of the different pulses of electrical current. If air-argon mixtures are used as feeding gas for the discharge, a sharp transition from a hot plume to a cold plasma jet is observed when argon content exceeds 90 %. Characteristics of the source are examined from the point of view of their utility as a tool for plasma treatment of materials. In this respect, a 10 % air in argon mixture corresponds to a promising oxidizing condition, as revealed by the pronounced peak in atomic oxygen emission intensity.

Atomic oxygen emission intensity ratio: Observation and theory

What constitutes reality: observation or theory? In the search for truth, observations can sometimes diverge from theory, forcing scientists to rethink fundamental approaches and question the idea of what it means for a system to exhibit “standard” behavior. In this Forum we argue that agreement among theoreticians on the numerical value of a particular physical parameter must still withstand the test of observation.

A two-dimensional cold atmospheric plasma jet array for uniform treatment of large-area surfaces for plasma medicine

For plasma treatment of inanimate surfaces and living tissues in medicine, it is important to control plasma–sample interactions and to mitigate non-uniform treatments of usually uneven sample surfaces so that effectiveness of application can be reproduced for different biological samples, relatively independently of their varying surface topologies and material characters. This paper reports a scalable two-dimensional (2D) array of seven cold atmospheric plasma (CAP) jets intended to achieve these two important requirements as well as to address the unique challenge of jet–jet interactions. While the CAP jet array can be configured to interact with a biological sample in either a direct mode (used with an in situ sample) or a remote mode (used as an afterglow), this study focuses on the direct mode. Using a downstream planar electrode as a sample model, the spatial distribution of reactive species and electrons delivered by individual jets of the 2D CAP jet array attains excellent uniformity. Specifically, the spatial variation over 100 μs is 5.6 and 7.9%, respectively, for wavelength-integrated optical emission intensity, and for atomic oxygen emission intensity at 845 nm when the oxygen admixture is 0.5% of the helium carrier gas. It is also shown that the highest emission intensity at 845 nm occurs at O2/He=0.5% under the best jet–jet uniformity conditions for O2/He=0.3–0.7%. These results indicate the potential of 2D CAP jet arrays for uniform treatment and for effective control of jet–jet interactions. Furthermore, spatial uniformity is accompanied by rich dynamics of jet–jet interactions and jet–sample interactions. Of the honeycomb-arranged seven CAP jets, the central jet is strongest in the negative half cycle, whereas the six surrounding jets (of uniform strength) are strongest in the positive half cycle. These dynamic features offer possible insights with which to better control jet–jet interactions and plasma–surface interactions in future.

Orography-caused variations in the 557.7 nm atomic oxygen emission intensity

For the first time, the spatial variations caused by the IGW generated in the troposphere when the air flow around the Kopet-Dag mountain ridge are detected based on the measurements of the spatial distribution of the 557.7 nm atomic oxygen emission intensity. The measurements were carried out at Vannovskii station, the Physicotechnical Institute, Academy of Sciences of the Turkmen SSR.

Empirical model of variations in the OI 630 nm emission. 1. Intensity

The empirical model of variations in the atomic oxygen emission intensity depending on different heliogeophysical conditions such as nighttime, lunar time, lunar phase age, season, year, and solar activity level during the 11-year cycle, as well as on cyclic aperiodic activity variations, level of geomagnetic disturbances, and their manifestations in the form of midlatitude subauroral red arcs, has been developed based on the long-term measurements of this emission intensity.

Molecular Formula Determination of Trimethylsilyl Derivatives of Lipids by Gas Chromatography-Microwave-Induced Plasma-Atomic Emission Spectrometry

Gas chromatography-microwave-induced plasma atomic emission spectrometry (GC-MIP-AES) was shown an effective means for determining the empirical formulae of fatty acid (FA), monoacylglycerol (MG) and diacylglycerol (DG) trimethylsilyl (TMS) ester (or ether) derivatives. Negative interference by silicon was demonstrated on an oxygen emission chromatogram. Negative interference and positive oxygen emission intensity decreased with increase in the rate of helium make-up gas flow. At optimal helium make-up gas flow (160mL/min), the oxygen number of the empirical formulae of FA, MG and DG-TMS derivatives were determined within ±0.3 atoms of theoretical formulae, and relative standard deviation (%) was less than 3.1% for FA-TMS, 4.1% for MG-TMS and 4.5% for DG-TMS.

High-power oxygen inductively coupled plasma discharge for spectrochemical analysis

The diagnostics of a high-power (4.2 and 3.2 kW) atmospheric-pressure oxygen inductively coupled plasma (at 27 MHz) reveals spatial temperature fields corresponding to a hot plasma discharge reaching 10200 K surrounded by a relatively low (> 4000 K) but uniform temperature zone. The electron number density is 10 14 to 10 16cm −3 in a zone above the induction coil. Steep thermal gradients exist at a radius of about 3.6mm corresponding to the edge of the luminous discharge. Measured radial temperature distributions from the absolute 0 I 715.7 nm and 615.8 nm line intensities are compared with theoretically calculated distributions. The plasma temperature field is shaped by the oxygen transport properties. The calculated equilibrium oxygen plasma composition indicates high (10 18 cm −3) atomic oxygen concentrations, although the analytical performance should not be limited by oxide formation in the regions of the discharge above 6000 K. Nebulization of water into the oxygen discharge increases the temperature of oxygen plasma and the oxygen emission intensities.

Superoxide, hydrogen peroxide and singlet oxygen in hematoporphyrin derivative-cysteine, -NADH and -light systems

Hematoporphyrin derivative and light in the presence of cysteine or glutathione were found to convert oxygen to superoxide and hydrogen peroxide at pH < approx. 6.5, while at pH > 6.5 no superoxide or hydrogen peroxide production was observed. However, at pH values greater than 6.5 the rate of oxygen consumption increased. This rate paralleled the acid dissociation curve of the cysteine thiol group and is consistent with the chemical quenching of 1O 2 by cysteine. The superoxide and hydrogen peroxide formation observed below pH 6.5 appeared not to be related to the singlet oxygen production of hematoporphyrin derivative. In addition, superoxide and hydrogen peroxide production was observed with hematoporphyrin derivative and light in the presence of NADH, both above and below pH 6.5. Direct detection of singlet oxygen luminescence at 1268 nm in the hematoporphyrin derivative-light system ( 2H 2O as solvent) revealed an apparent linear increase in the singlet oxygen emission intensity as the p 2H was raised from 7.0 to 10.0. Azide efficiently quenched this observed emission. In addition, at p 2H 7.4, 1 mM cysteine resulted in a 40% reduction of the singlet oxygen luminescence, while at p 2H 9.4 the signal was quenched by over 95% (under the experimental conditions employed). In total, we interpret these results as consistent with the chemical quenching of 1O 2 by the ionized thiol group of cysteine.

Plasma etching of organic materials. I. Polyimide in O2–CF4

Gas phase and surface phenomena responsible for etching polyimide in O2–CF4 rf plasmas have been investigated. The dependence of the etch rate of polyimide on the relative concentrations of these two gases was compared with data from optical emission spectra, mass spectra, and x-ray photoelectron spectroscopy (XPS). The increase in O atom number density in the plasma with addition of CF4 to O2 certainly increases etch rates over those achieved in pure oxygen plasmas. However, etch rates do not track identically with atomic oxygen emission intensities. Etch rates are enhanced through the reaction of fluorine in the polyimide surface layer while fluorine present in excess inhibits etching through competition with oxygen atoms, resulting in the formation of CF2 type bonding at the surface. Removal of the resulting passivation is most efficiently accomplished by exposure of the polyimide to a plasma with higher oxygen concentration, probably due to the presence of ions. The position of the maximum in etch rate distribution with respect to CF4 concentration depends on an optimum ratio of O to F atoms in the plasma.