Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “high-resolution spectroscopy”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 19 records

Detection of O2 dayglow emission from Mars and the Martian ozone abundance

High-resolution spectroscopy of Mars in the vicinity of 1.27 microns has revealed the presence of emission lines of O2 which are interpreted as the result of production of O2(1 delta g) in the ultraviolet photolysis of Martian ozone. In the equatorial region of Mars, the dayglow intensity implies an ozone abundance near 0.2 microatm, which seems consistent with theoretical models which utilize the measured water-vapor abundance. A much larger ozone abundance exists in the atmosphere at high winter latitude, in agreement with direct measurement of ozone absorption performed by the Mariner spacecraft.

Noxon, J. F.↗

High-resolution threshold photoelectron spectroscopy by electron attachment

A new technique for measuring high-resolution threshold photoelectron spectra of atoms, molecules, and radicals is described. It involves photoionization of a gaseous species, attachment of the threshold, or nearly zero electron to some trapping molecule (here SF6 or CFCl3), and mass detection of the attachment product (SF6/-/ or Cl/-/ respectively). This technique of threshold photoelectron spectroscopy by electron attachment was used to measure the spectra of argon and xenon at 11 meV (FWHM) resolution, and was also applied to CFCl3.

Ajello, J. M.↗

A high-resolution Fourier Transform Spectrometer for planetary spectroscopy

The employment of a high-resolution Fourier Transform Spectrometer (FTS) is described for planetary and other astronomical spectroscopy in conjunction with the 88-inch telescope at Mauna Kea Observatory. The FTS system is designed for a broad range of uses, including double-beam laboratory spectroscopy, infrared gas chromatography, and nuclear magnetic resonance spectroscopy. The data system is well-suited to astronomical applications because of its great speed in acquiring and transforming data, and because of the enormous storage capability of the magnetic tape unit supplied with the system. The basic instrument is outlined 2nd some of the initial results from the first attempted use on the Mauna Kea 88-inch telescope are reported.

Cruikshank, D. P.↗

Galactic X-ray polarimetry and high-resolution X-ray spectroscopy.

Stellar X-ray spectroscopy and polarimetry are discussed in terms of the source parameters that can be determined through such studies and in terms of the constraints that these studies will place on theoretical models. The spectroscopic and polarimetric results that have been obtained to date are reviewed. These include the recent discovery of X-ray polarization in the Crab Nebula and the recent evidence for X-ray coronal line emission in the Cygnus Loop. Finally, the properties and predicted performance of a number of satellite-borne spectrometers and polarimeters are presented.

Novick, R.↗

Stratospheric composition measurements of earth and Titan using high-resolution tunable diode laser spectroscopy

Field and laboratory measurements of species of atmospheric interest made as part of the JPL diode laser spectroscopy program are presented. Stratospheric measurements of NO2, NO, CO2, and H2O made in November 1985 using the BLISS instrument are reported, together with recent laboratory measurements of spectral line parameters of HNO3 and HO2NO2. In addition, a novel diode laser instrument concept for the in situ sensing of Titan's atmosphere is described for the Saturn Orbiter/Titan Probe (SOTP) Cassini Mission.

Webster, Christopher R.↗

Self-scanned Digicon - A digital image tube for astronomical spectroscopy

We have successfully fabricated, tested, and operated a digital image tube consisting of a magnetically focused image intensifier tube in which a self-scanned linear array of 1024 silicon photodiodes operating in the EBS mode serves as the photoelectron image detector, amplifier, and intermediate image storage device. Integral on-chip MOS shift registers driven by an external clock sequentially interrogate the photodiodes through MOS FET multiplex switch arrays. Each output frame is a sequence of 256 analog pulses on each of four video lines. Laboratory and observing tests show that the output signal is photoelectron shot noise limited over at least a range of 1-100,000 detected photoelectrons per picture element, indicating that single photon detection is achieved. High-resolution astronomical spectroscopy has been carried out in the coude spectrograph of the 2.7-m telescope at McDonald Observatory. Examples are shown.

Tull, R. G.↗

Study of carbon compounds in Apollo 12 and 14 lunar samples.

The results of gas-chromatography and high-resolution mass spectroscopy studies of gases released on deuterium fluoride dissolution of Apollo 12 and 14 lunar samples are reported. The results confirm previous observations that CH4 and C2H6 are released as well as CD4, C2D4, C2D6, and higher deuterated hydrocarbons. The yields correlate with the total carbon content of the samples, and the CH4 and C2H6 released may be regarded as indigenous, while the deuterated products result from hydrolysis of carbide material. The results provide the first experimental confirmation of the hypothesis that the CH4 derives from solar wind interactions.

Holland, P. T.↗

Auger electron spectroscopy at high spatial resolution and nA primary beam currents

An experimental Auger microprobe system is described which incorporates a field-emission electron gun and total beam currents in the nanoampere range. The distinguishing characteristics of this system include a large multistation UHV specimen chamber, pulse counting and fully digital Auger signal-processing techniques, and digital referencing methods to eliminate the effects of beam instabilities. Some preliminary results obtained with this system are described, and it is concluded that field-emission electron sources can be used for high-resolution Auger electron spectroscopy with primary-beam spots of less than 100 nm and beam currents of the order of 1 nA.

Todd, G.↗

Balloon-borne transform spectroscopy

The design and construction of a high-resolution far-infrared Fourier-transform spectrometer for use on the Smithsonian balloon-borne one-meter telescope is described. The instrument will operate at a resolution of about 0.1 kayser in the region from 25 to 150 microns. It will be used to obtain spectra of Jupiter, Venus, Orion, and other H II and molecular cloud regions, as well as the terrestrial stratosphere.

Traub, W. A.↗

Accretion flows in binary X-ray systems

Recent developments in the study of accretion flows in binary X-ray systems are reviewed, concentrating on issues concerning the gas flows rather than the radiation mechanisms. A model for Her X-1 is presented which illustrates the main structures expected to exist in the case where mass transfer is by Roche-lobe overflow and the X-ray source is a rotating magnetized neutron star. A model for Cyg X-1 is given which shows the accretion-flow structures to be expected if the compact object is a black hole, including an accretion wake and a very small accretion disk around the black hole. Physical parameters of the accretion flows in these two instances are examined along with some scale lengths that may be derived from these parameters by dimensional analysis. Detailed attention is given to neutron-star magnetospheres (for slow, intermediate, and fast rotators), accretion-disk structure, accretion from stellar winds, and the relationship between X-rays and the gas dynamics of accretion flows. It is suggested that accretion flows in binary X-ray systems be observed directly by means of high-resolution UV and X-ray spectroscopy.

Mccray, R.↗

Improved source of infrared radiation for spectroscopy

Radiation from a crimped V-groove in the electrically heated metallic element of a high-resolution infrared spectrometer is more intense than that from plane areas adjacent to the element. Radiation from the vee and the flat was compared by alternately focusing on the entrance slit of a spectrograph.

Burkhard, D. G.↗

Atmospheric absorption measurements in the region of 1 mm wavelength.

A Froome-type plasma-metal-junction device (1962) was used in high-resolution radiation transmission measurements in the atmosphere at wavelengths from 0.5 to 3.0 mm. The experimental and theoretical results for water vapor absorption lines in two submillimeter wavelength windows were compared, showing that this technique provided a much higher wavelength accuracy than more conventional optical-type spectroscopy.

Emery, R.↗

The Telecommunications and Data Acquisition Report

This quarterly publication provides archival reports on developments in programs managed by JPL's Office of Telecommunications and Data Acquisition (TDA). In space communications, radio navigation, radio science, and ground-based radio and radar astronomy, it reports on activities of the Deep Space Network (DSN) in planning, supporting research and technology, implementation, and operations. Also included are standards activity at JPL for space data and information systems and reimbursable DSN work performed for other space agencies through NASA. The preceding work is all performed for NASA's Office of Space Communications (OSC). The TDA Office also performs work funded by another NASA program office through and with the cooperation of OSC. This is the Orbital Debris Radar Program with tile Office of Space Systems Development. The TDA Office is directly involved in several tasks that directly support the Office of Space Science (OSS), with OSC funding DSN operational support. In radio science, The TDA Progress Report describes the spacecraft radio science program conducted using tile DSN. For the High-Resolution Microwave Survey (HRMS), the report covers implementation and operations for searching the microwave spectrum. In solar system radar, it reports on the uses of the Goldstone Solar System Radar for scientific exploration of the planets, their rings and satellites, asteroids, and comets. In radio astronomy, the areas off support include spectroscopy, very long baseline interferometry, and astrometry.

Edward C Posner↗

Solar flares

A review of the knowledge about solar flares which has been obtained through observations from the earth and from space by various methods. High-resolution cinematography is best carried out at H-alpha wavelengths to reveal the structure, time history, and location of flares. The classification flares in H alpha according to either physical or morphological criteria is discussed. The study of flare morphology, which shows where, when, and how flares occur, is important for evaluating theories of flares. Consideration is given to studies of flares by optical spectroscopy, radio emissions, and at X-ray and XUV wavelengths. Research has shown where and possibly why flares occur, but the physics of the instability involved, of the particle acceleration, and of the heating are still not understood.

Zirin, H.↗

Far-infrared spectroscopy of the Orion Nebula

A coarse-resolution spectrum of the Orion Nebula between 75 and 120 microns closely fits the color dependence of a 75 K blackbody. A high-resolution search for O III at 88.16 microns yields an upper limit below theoretical predictions.

Ward, D. B.↗