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The solar spectrum region lambda lambda 6327.5 to 6330.0 AA was investigated. Six new telluric lines were found. The behavior of two of them (lambda 6328.51 and lambda 6328.71 A) is the same as identified molecular oxygen lines in the region. The lines lambda 6328.27, 6329.12, and 6329.29 A are more intensive when there are days with high humidity.
A computer code has been developed which is used to calculate ab initio the laboratory shapes and energy shifts of gamma-ray lines from (C-12)(p, gamma/4.438/)p-prime(C-12) and (O-16)(p, gamma/6.129/)p-prime(O-16) reactions and to calculate the expected shapes of these lines from solar flares. The sensitivity of observable solar flare gamma-ray line shapes to the directionality of the incident particles is investigated for several projectile angular distributions. Shapes of the carbon and oxygen lines are calculated assuming realistic proton energy spectra for particles in circular orbits at the mirror points of magnetic loops, for particle beams directed downward into the photosphere, and for isotropic particle distributions. Line shapes for flare sites near the center of the sun and on the limb are shown for both thin-target and thick-target interaction models.
A number of faint filaments in the Puppis A supernova remnant have been found to have spectra with strong oxygen lines, extremely weak Balmer lines, and radial velocities greater than 1500 km/s. These are very different from the bright filaments, which are nitrogen-rich and have velocities less than 300 km/s. The newly discovered filaments are spectroscopically similar to those found in young, oxygen-rich remnants, as typified by the fast-moving knots in Cas A. These Puppis A filaments are interpreted as knots of oxygen-rich supernova ejecta which remain relatively uncontaminated by interstellar material, despite the probable age of Puppis A of several thousand years. Spectra of the newly discovered filaments show, in addition to strong forbidden lines of O I, O II, and O III, permitted lines of O I: 7774, 8446 A. The permitted lines are attributed to recombination of O(+), and their strength relative to H is used to estimate that the O:H mass ratio is about 30.
Zeippen, Seaton, and Morton (1977) recently published profiles of interstellar neutral oxygen lines in Zeta Oph. From a reconsideration of the profiles of visual interstellar lines to that star, it follows that the cloud dominating the O I absorption could have a very small velocity spread, approximately 0.5 km/s. Analysis of the profile of the 1302-A line gives a column density of O I in that cloud of 6.0 + or - 5 x 10 to the 17th per sq cm. This implies an upward revision of the abundance of free oxygen by a factor 1.5 and hence that oxygen is only 25% depleted in the gas to Zeta Oph, contrary to the minimum depletion of a factor 1.8 found by Zeippen, Seaton, and Morton. This small depletion of oxygen in interstellar gas is consistent with the widespread absence of absorption by H2O ice mantles on interstellar dust grains.
High resolution X-ray spectral observations of Puppis A were performed with the FPCS on the Einstein Observatory at three regions of the remnant: the shock front, the bright eastern knot, and the interior. Plasma diagnostics of lines from OVII and OVIII constrain the values of electron temperature, ionization timescale, and hydrogen column density. Results of the diagnostics for these three regions are compared. A nonequilibrium analysis of previously published fluxes of oxygen lines shows that the interior has not yet reached ionization equilibrium.
We analyze the oxygen abundances of a stellar sample representative of the two major Galactic populations: the thin and thick disks. The aim is to investigate the differences between members of the Galactic disks and contribute to the understanding of the origin of oxygen chemical enrichment in the Galaxy. The analysis is based on the [O i] = 6300.30 Å oxygen line in high-resolution spectra (R ∼ 52,500) obtained from the Gaia-ESO public spectroscopic Survey (GES). By comparing the observed spectra with a theoretical data set computed in LTE with the SPECTRUM synthesis and ATLAS12 codes, we derive the oxygen abundances of 516 FGK dwarfs for which we have previously measured carbon abundances. Based on kinematic, chemical, and dynamical considerations, we identify 20 thin and 365 thick disk members. We study the potential trends of both subsamples in terms of their chemistry ([O/H], [O/Fe], [O/Mg], and [C/O] versus [Fe/H] and [Mg/H]), age, and position in the Galaxy. The main results are that (a) [O/H] and [O/Fe] ratios versus [Fe/H] show systematic differences between thin and thick disk stars with an enhanced O abundance of thick disk stars with respect to thin disk members and a monotonic decrement of [O/Fe] with increasing metallicity, even at metal-rich regime; (b) there is a smooth correlation of [O/Mg] with age in both populations, suggesting that this abundance ratio can be a good proxy of stellar ages within the Milky Way; and (c) thin disk members with [Fe/H] ≃ 0 display a [C/O] ratio smaller than the solar value, suggesting a possibly outward migration of the Sun from lower Galactocentric radii.
High-resolution (0.3 A) CCD spectra obtained at the 200 in. coude spectrograph have been analyzed for the abundances of O, Sc, Fe, and La in four stars in the globular cluster M13. Fe/H abundance is found to be = -1.6, as found by many other observers of this cluster. For three stars O/Fe abundance is found to be = +0.3 + or - 0.1, which is similar to O/Fe ratios in other globular clusters and metal-poor field stars. For star II-67, no oxygen line is visible at 6300 A and O/Fe abundance is found to be not greater than -0.4 (for a high carbon content) and not greater than -0.7 (for a low carbon content). The latter is more likely to be correct. Two possible explanations of the oxygen deficiency in II-67 are discussed: primordial deficiency, and CNO cycling at or above a temperature of 25,000,000 K.
The Galactic/Extra Ultra long Duration Balloon Spectroscopic-Stratospheric Terahertz Observatory (GUSTO), is a NASA balloon-borne project and is scheduled for launch in late 2022. The balloon will carry a spectroscopic telescope that will detect three brightest emission lines from interstellar medium. GUSTO measurements will shed light on the life-cycle of the gases in the Milky Way and Large Magellanic Cloud (LMC). In this study, we will discuss the details of a quantum cascade laser used in the local oscillator for detecting the oxygen line at 4.74 THz.
A study of short-gated 10 nanosecond (ns), 100 picosecond (ps), and 100 femtosecond (fs) laser induced breakdown spectroscopy (LIBS) was conducted for fuel-to-air ratio (FAR) measurements in an atmospheric Hencken flame. The intent of the work is to understand which emission lines are available near the optical range in each pulse width regime and which emission ratios may be favorable for generating equivalence ratio calibration curves. The emission spectra in the range of 550–800 nm for ns-LIBS and ps-LIBS are mostly similar with slightly elevated atomic oxygen lines by ps-LIBS. Spectra from fs-LIBS show the lowest continuum background and prominent individual atomic lines, though have significantly weaker ionic emission from nitrogen. A qualitative explanation based on assumed local thermodynamic equilibrium and electron temperatures calculated by the N I I ( 565 n m ) and N I I ( 594 n m ) emissions is presented. In studying line emission ratios for FAR calculation, it is found that H α <#comment/> ( 656 n m ) / N I I ( 568 n m ) is best for FAR measurements with ns-LIBS and remains viable for ps-LIBS, while H α <#comment/> ( 656 n m ) / O I ( 777 n m ) is optimal for the ps-LIBS and fs-LIBS cases. Due to low continuum background and short time delay for spectra collection, fs-LIBS is very promising for high-speed FAR measurements using short-gated LIBS.
Two intense microwave spectra lines exist in the martian atmosphere that allow unique sounding capabilities: water vapor at 183 GHz and the (2-1) rotational line of CO at 230 GHz. Microwave spectra line sounding is a well-developed technique for the Earth's atmosphere for sounding from above from spacecraft and airplanes, and from below from fixed surface sites. Two simple instruments for temperature sounding on Mars (the CO line) and water vapor measurements are described. The surface sounder proposed for the MESUR sites is designed to study the boundary layer water vapor distribution and the temperature/pressure profiles with vertical resolution of 0.25 km up to 1 km with reduced resolution above approaching a scale height. The water channel will be sensitive to a few tenths of a micrometer of water and the temperature profile will be retrieved to an accuracy between 1 and 2 K. The latter is routinely done on the Earth using oxygen lines near 60 GHz. The measurements are done with a single-channel heterodyne receiver looking into a 10-cm mirror that is canned through a range of elevation angles plus a target load. The frequency of the receiver is sweep across the water and CO lines generating the two spectra at about 1-hr intervals throughout the mission. The mass and power for the proposed instrument are 2 kg and 5-8 W continuously. The measurements are completely immune to the atmospheric dust and ice particle loads. It was felt that these measurements are the ultimate ones to properly study the martian boundary layer from the surface to a few kilometers. Sounding from above requires an orbiting spacecraft with multichannel microwave spectrometers such as the instrument proposed for MO by a subset of the authors, a putative MESUR orbiter, and a proposed Discovery mission called MOES. Such an instrument can be built with less than 10 kg and use less than 15 W. The obvious advantage of this approach is that the entire atmosphere can be sounded for temperature and water vapor in a few hours with somewhat better than a scale height resolution. If a bigger mirror is used (greater than 30 cm) limb sounding geometry can be employed and half scale height resolution achieved to altitudes up to at least 60 km. Again, the measurements are immune to dust and ice loads. Water vapor sensitivity of 0.1 micrometer can be achieved (even with a nadir instrument) and temperature profiles retrieved to an accuracy of better than 2 K from the surface to about 60 km. Winds can be measured from the doppler shifts of CO lines in the limb sounding mode.
Ligand-appended pillar[5]arene (LAP) channels are emerging as a promising platform for ion-selective membranes. In this study, we investigated the ion selectivities of three LAP channels functionalized with distinct ligands: diglycolamine, carbamoylmethyl phosphine oxide, and propionamide phosphonic acid. These ligands were chosen based on their demonstrated affinities for lanthanides in solvent extraction studies. We examined the selectivity of each channel toward a series of monovalent, divalent, and trivalent ions: Li + , Na + , K + , Mg 2+ , Ca 2+ , La 3+ , Eu 3+ , and Yb 3+ . To quantify ion-channel interactions and the energetics of translocation, we computed the potential of mean force (PMF) profiles for each ion. These PMFs were subsequently recast into permeability coefficients, enabling a direct evaluation of ion permselectivity. Our results reveal distinct selectivity patterns governed by the chemical nature of the appended ligands. The diglycolamine-functionalized channel exhibits strong interactions with monovalent ions, leading to replication of the Li + bulk hydration shell within the channel. This promotes preferential transport Li + ions while effectively excluding divalent and trivalent species. In contrast, the carbamoylmethyl phosphine oxide-functionalized channel displays a reduced selectivity between monovalent ions while similarly exhibiting an effective rejection of divalent and trivalent ions. This arises from steric hindrance around channel-lining oxygens imposed by the ligand's bulky phenyl groups which limits heavy ion coordination and promotes retention of hydration shells effectively increasing effective ion size. The propionamide phosphonic acid-functionalized channel exhibits a different trend, favoring ions with lower hydration free energies, with K + ions showing enhanced permeation. These findings highlight the critical role of ligand-ion interactions in modulating ion selectivity within LAP channels. In particular, the strong coordination exhibited by diglycolamine and propionamide phosphonic acid ligands significantly influences the ion transport energetics and selectivity profiles.
Mars hosts various auroral processes despite the planet’s tenuous atmosphere and lack of a global magnetic field. To date, all aurora observations have been at ultraviolet wavelengths from orbit. We describe the discovery of green visible-wavelength aurora, originating from the atomic oxygen line at 557.7 nanometers, detected with the SuperCam and Mastcam-Z instruments on the Mars 2020 Perseverance rover. Near–real-time simulations of a Mars-directed coronal mass ejection (CME) provided sufficient lead-time to schedule an observation with the rover. The emission was observed 3 days after the CME eruption, suggesting that the aurora was induced by particles accelerated by the moving shock front. To our knowledge, detection of aurora from a planetary surface other than Earth has never been reported, nor has visible aurora been observed at Mars. This detection demonstrates that auroral forecasting at Mars is possible, and that during events with higher particle precipitation, or under less dusty atmospheric conditions, aurorae will be visible to future astronauts.
The statistical analysis of historic pressure and temperature profiles from radiosonde launches for use in the fitting of molecular oxygen line shapes is presented. As the O 2 mixing ratio is nearly constant throughout the lower atmosphere, only variations in pressure and temperature profiles will affect the fit of observed O 2 features in Laser Heterodyne Radiometry (LHR) spectra. Radiosonde temperature and pressure data are extracted from the Integrated Global Radiosonde Archive (IGRA) for a given station, date, and launch time. Data may be extracted for a single launch, for the same date over several years, and/or within a window centered on a target date. The temperature and pressure profiles are further characterized by the statistical variation in coefficients of polynomial fits in altitude. The properties of the probability distributions for each coefficient are used to constrain fits of O 2 line shapes through Nelder–Mead optimization. The refined temperature and pressure profiles are then used in the retrieval of vertically resolved mixing ratios for greenhouse gases (GHGs) measured in the same instrument. In continuous collections, each vertical profile determination may be treated as a Bayesian prior to inform subsequent measurements and provide an estimate of uncertainties.
Electrophotometric observations on spatial discontinuities of green atomic oxygen line in airglow spectrum
Mars upper atmosphere ionized carbon dioxide and CO emission spectra in 1900-4300 A region measured by Mariner 6, observing atomic hydrogen and oxygen lines
Exospheric evening temperature behavior data, using Fabry-Perot interferometer measurements of atomic oxygen line Doppler broadening
The application of fire resistant spacecraft materials to the interior design of commercial aircraft is discussed. The use of such materials for curtains, upholstery, carpets, decorative panels, cabinets, paper products, and oxygen lines is examined. It is concluded that the highest degree of nonflammability can be obtained with inorganic fibers such as asbestos and fiber glass. The application of various chemical compounds for specific purposes is presented.
By analyzing all existing frequency data of the oxygen molecule in microwave, submillimeter, and infrared spectroscopy, a new set of molecular parameters is obtained. The parameters are tabulated and compared with values obtained by other authors. Observed and calculated frequencies of oxygen lines are also given.