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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.

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At least 109 records · Page 6
All sourcesNASA NTRSDOE OSTI
NASA NTRS1975

Molecular spectroscopy and collisional excitation

The paper examines the basic principles underlying the molecular transitions responsible for interstellar molecular spectra. The energy levels of molecules are discussed in detail with special attention given to the Born-Oppenheimer approximation, the electronic Hamiltonian, and the parameters of vibrational and rotational energy. The probabilities for radiative and collisional transitions are calculated. A brief review of techniques for molecular spectroscopy is presented along with methods used to determine collision cross sections on both an experimental and a theoretical basis.

Green, S.↗
NASA NTRS1983

Comparison of CARS combustion temperatures with standard techniques

This paper describes a comparative study of temperatures measured with Coherent Anti-Stokes Raman Spectroscopy (CARS) and those using standard measurement techniques. CARS temperatures from nitrogen vibrational-rotational spectra have been obtained in a premixed hydrogen-air laboratory flame supported on a flat flame burner over a temperature range from about 1000 K to 2100 K. The techniques used for comparison were sodium line reversal, thin wire thermocouples and heat balance calculations. These studies show a good agreement over the entire temperature range studied.

Antcliff, R. R.↗
NASA NTRS1996

Small Business Innovations

Under a Small Business Innovation Research (SBIR) contract to Kennedy Space Center, EIC Laboratories invented a Raman Spectrograph with fiber optic sampling for space applications such as sensing hazardous fuel vapors and making on-board rapid analyses of chemicals and minerals. Raman spectroscopy is a laser-based measurement technique that provides through a unique vibrational spectrum a molecular 'fingerprint,' and can function in aqueous environments. EIC combined optical fiber technology with Raman methods to develop sensors that can be operated at a distance from the spectrographic analysis instruments and the laser excitation source. EIC refined and commercialized the technology to create the Fiber Optic Raman Spectrograph and the RamanProbe. Commercial applications range from process control to monitoring hazardous materials.

Source record↗
NASA NTRS2005

NASA Tech Briefs, May 2005

Topics covered include: Fastener Starter; Multifunctional Deployment Hinges Rigidified by Ultraviolet; Temperature-Controlled Clamping and Releasing Mechanism; Long-Range Emergency Preemption of Traffic Lights; High-Efficiency Microwave Power Amplifier; Improvements of ModalMax High-Fidelity Piezoelectric Audio Device; Alumina or Semiconductor Ribbon Waveguides at 30 to 1,000 GHz; HEMT Frequency Doubler with Output at 300 GHz; Single-Chip FPGA Azimuth Pre-Filter for SAR; Autonomous Navigation by a Mobile Robot; Software Would Largely Automate Design of Kalman Filter; Predicting Flows of Rarefied Gases; Centralized Planning for Multiple Exploratory Robots; Electronic Router; Piezo-Operated Shutter Mechanism Moves 1.5 cm; Two SMA-Actuated Miniature Mechanisms; Vortobots; Ultrasonic/Sonic Jackhammer; Removing Pathogens Using Nano-Ceramic-Fiber Filters; Satellite-Derived Management Zones; Digital Equivalent Data System for XRF Labeling of Objects; Identifying Objects via Encased X-Ray-Fluorescent Materials - the Bar Code Inside; Vacuum Attachment for XRF Scanner; Simultaneous Conoscopic Holography and Raman Spectroscopy; Adding GaAs Monolayers to InAs Quantum-Dot Lasers on (001) InP; Vibrating Optical Fibers to Make Laser Speckle Disappear; Adaptive Filtering Using Recurrent Neural Networks; and Applying Standard Interfaces to a Process-Control Language.

Source record↗
NASA NTRS2012

The Composition of Comet C/2009 P1 (Garradd) from Infrared Spectroscopy: Evidence for an Oxygen-Rich Heritage?

Comets retain relatively primitive icy material remaining from the epoch of Solar System formation, however the extent to which their ices are modified remains a key question in cometary science. One way to address this is to measure the relative abundances of primary (parent) volatiles in comets (i.e., those ices native to the nucleus). High-resolution (lambda/delta lambda greater than 10(exp 4)) infrared spectroscopy is a powerful tool for measuring parent volatiles in comets through their vibrational emissions in the approximately 3-5 micrometer region. With modern instrumentation on world-class telescopes, we can quantify a multitude of species (e.g., H2O, C2H2, CH4, C2H6, CO, H2CO, CH3OH, HCN, NH3), even in comets with modest gas production. In space environments, compounds of keen interest to astrobiology could originate from HCN and NH3 (leading to amino acids), H2CO (leading to sugars), or C2H6, and CH4 (suggested precursors of ethyl- and methylamine). Measuring the abundances of these precursor molecules and their variability among comets contributes to understanding the synthesis of the more complex prebiotic compounds.

DiSanti, M. A.↗
NASA NTRS2012

The Composition of Comet C/2009 PI (Garradd) from Infrared Spectroscopy: Evidence for an Oxygen-Rich Heritage?

Comets retain relatively primitive icy material remaining from the epoch of Solar System for111ation, however the extent to which their ices are modified remains a key question in cometary science. One way to address this is to measure the relative abundances of primary (parent) volatiles in comets (i.e., those ices native to the nucleus). High-resolution (lambda/delta lambda greater than 10(exp 4)) infrared spectroscopy is a powerful tool for measuring parent volatiles in comets through their vibrational emissions in the ~ 3-5 micrometer region. With modern instrumentation on worldclass telescopes, we can quantify a multitude of species (e.g., H2O, C2H2, CH4, C2H6 CO, H2CO, CH3OH, HCN, NH3), even in comets with modest gas production. In space environments, compounds of keen interest to astrobiology could originate from HCN and NH3 (leading to amino acids), H2CO (leading to sugars), or C2H6 and CH4 (suggested precursors of ethyl- and methylamine). Measuring the abundances of these precursor molecules and their variability among comets contributes to understanding the synthesis of the more complex prebiotic compounds.

DiSanti, M. A.↗
NASA NTRS1996

Visualizing Infrared (IR) Spectroscopy with Computer Animation

IR Tutor, an interactive, animated infrared (IR) spectroscopy tutorial has been developed for Macintosh and IBM-compatible computers. Using unique color animation, complicated vibrational modes can be introduced to beginning students. Rules governing the appearance of IR absorption bands become obvious because the vibrational modes can be visualized. Each peak in the IR spectrum is highlighted, and the animation of the corresponding normal mode can be shown. Students can study each spectrum stepwise, or click on any individual peak to see its assignment. Important regions of each spectrum can be expanded and spectra can be overlaid for comparison. An introduction to the theory of IR spectroscopy is included, making the program a complete instructional package. Our own success in using this software for teaching and research in both academic and industrial environments will be described. IR Tutor consists of three sections: (1) The 'Introduction' is a review of basic principles of spectroscopy. (2) 'Theory' begins with the classical model of a simple diatomic molecule and is expanded to include larger molecules by introducing normal modes and group frequencies. (3) 'Interpretation' is the heart of the tutorial. Thirteen IR spectra are analyzed in detail, covering the most important functional groups. This section features color animation of each normal mode, full interactivity, overlay of related spectra, and expansion of important regions. This section can also be used as a reference.

Charles B. Abrams↗
NASA NTRS1990

Determination of molecular spectroscopic parameters and energy-transfer rates by double-resonance spectroscopy

The spectroscopy of small to medium-size polyatomic molecules can be extremely complex, especially in higher-lying overtone and combination vibrational levels. The high density of levels also complicates the understanding of inelastic collision processes, which is required to model energy transfer and collision broadening of spectral lines. Both of these problems can be addressed by double-resonance spectroscopy, i.e., time-resolved pump-probe measurements using microwave, infrared, near-infrared, and visible-wavelength sources. Information on excited-state spectroscopy, transition moments, inelastic energy transfer rates and propensity rules, and pressure-broadening parameters may be obtained from such experiments. Examples are given for several species of importance in planetary atmospheres, including ozone, silane, ethane, and ammonia.

Steinfeld, J. I.↗
NASA NTRS1974

On the ionization potential of molecular oxygen

The ionization potential of O2 was measured by the technique of high resolution photoelectron spectroscopy taking into account the influence of rotational structure on the shape of the vibrational bands. A value of 12.071 + or - .001 eV (1027.1 + or - 0.1 A) was found for the ionization potential. A lowering of the ionization potential caused by a branch-head when delta N = -2 gave an appearance potential for ionization of 12.068 + or - .001 eV (1027.4 + or - 0.1 A).

Samson, J. A. R.↗
NASA NTRS1994

Imaging spectroscopy of the solar CO lines at 4.67 microns

We analyze spatially and temporally resolved spectra of the fundamental vibration-rotation transitions of carbon monoxide (CO) in the solar spectrum at 4.67 micrometers. Our observations imply that, in the quiet Sun, spatial variations in CO intensity are largely dynamical in nature, reinforcing the suggestion that dynamical effects play a key role in the formation of the dark CO cores. Time sequences of resolved spectra exhibit mainly 3 minute power in line-core intensity but mainly a 5 minute period in Doppler shift. The weak 7-6 R68 line shows normal Evershed flow in the penumbra of a sunspot; we find evidence for the onset of inverse Evershed flow in the strong 3-2 R14 line. Spectra at the limb indicate that 3-2 R14 emission extends approximately 360 km beyond the continuum limb.

Uitenbroek, Han↗
NASA NTRS1985

Molecular spectroscopy from the Kuiper Airborne Observatory

Interstellar and circumstellar molecules are investigated through medium-resolution infrared spectrosocpy of the vibration-rotation and pure rotational transitions. A primary goal was the construction and improvement of instrumentation for the near and middle infrared regions, wavelengths between 2 and 10 microns. The main instrument was a cooled grating spectrometer with an interchangeable detector focal plane which could be used on the Kuiper Airborne Observatory (KAO) for airborne observations, and also at ground-based facilities. Interstellar shock waves were investigated by H2 emission from the Orion Nebula, W51, and the proto-planetary nebulae CRL 2688 and CRL 618. The observations determined the physical conditions in shocked molecular gas near these objects. From these it was possible to characterize the energetic history of mass loss from both pre- and post-main sequence stars in the regions.

Beckwith, S.↗
NASA NTRS1989

High-resolution near-infrared spectroscopy of water dimer

High-resolution near-infrared spectra are reported for all of the O-H stretch vibrational bands of the water dimer. The four O-H vibrations are characterized as essentially independent proton-donor or proton-acceptor motions. In addition to the rotational and vibrational information contained in these spectra, details are obtained concerning the internal tunneling dynamics in both the ground and excited vibrational states. These results show that, for tunneling motions which involve the interchange of the proton donor and acceptor molecules, the associated frequencies decrease substantially due to vibrational excitation. The predissociation lifetimes for the various states of the dimer are determined from linewidth measurements. These results clearly show that the predissociation dynamics is strongly dependent on the tunneling states, as well as the Ka quantum number, indicating that the internal tunneling dynamics plays an important role in determining the dissociation rate in this complex.

Huang, Z. S.↗
NASA NTRS1996

The v4 Band of FNO2

We report the first high resolution infrared spectra of nitryl fluoride, FNO(sub 2). The intense V(sub 4) band, associated with the NO(sub 2) antisymmetric streteching vibration, has been observed.

high resolution spectroscopy infrared b-type trans↗
NASA NTRS1982

Effect of hydrogen bonding on the vibrational dephasing time in glycerol

The vibrational dephasing of the methyl CH2 symmetric stretch mode in glycerol was directly measured over an extended temperature range using picosecond coherent Raman pump and probe spectroscopy. The dephasing time was found to increase dramatically as the temperature of the supercooled liquid was lowered. This observation is attributed to the increased hydrogen bonding with decreasing temperature which hinders the dephasing of the CH2 vibration by reducing molecular motions.

Dorsinville, R.↗
NASA NTRS1979

Optical constants of alcohols in the infrared

The spectral reflectances at near-normal incidence for methanol, ethanol, 1-propanol, 1-butanol, and 1-pentanol are reported for the spectral range 6700-350 kaysers. The real and imaginary parts of the complex index of refraction of these liquids are obtained in the range 4000-400 kaysers by use of Kramers-Kronig phase-shift analysis. For all of the alcohols studied, the strength for the OH-stretch bands is directly proportional to the number of OH groups per unit volume; similar relations are established for CH- and CO-stretch bands. Absorption cross sections for stretch vibrations of the three groups are considered, and the role of characteristic group intensities in intensity spectroscopy is discussed.

Sethna, P. P.↗
NASA NTRS1980

A laboratory study on the dissociative recombination of vibrationally excited O2/+/ions

The dissociative recombination of vibrationally excited O2(+) ions is studied in light of the possible importance of this reaction in upper atmospheric chemistry. A plasma spectroscopy experiment was performed in a microwave cavity filled by an argon-oxygen mixture, with O(1S) production monitored by measurements of the 5577-A afterglow, the O2(+) density and the electron concentration. Plasma and optical data reveal the predominant afterglow ions to be Ar2(+) and O2(+), with an effective O(1S) dissociative recombination coefficient of 2.1 x 10 to the -8th cu cm/sec, corresponding to a quantum yield of 10%. Experiments with an argon-krypton-oxygen mixture reveal that vibrationally excited O2(+) ions are the chief source of the O(1S) atoms, with a specific recombination coefficient for the dissociation of O2(+)(2 pi g) into O(1S) and O(1D) of 4.2 x 10 to the -9th cu cm/sec. A comparison of the laboratory results with Atmospheric Explorer data on the 5577-A airglow implies that O2(+) ions in the sunlit ionosphere are vibrationally excited to the same degree as in the laboratory, with the vibrational relaxation of these ions much slower than dissociative recombination. Results also predict a dawn-twilight asymmetry in the effective O(1S) yield due to the normal variation of electron content.

Zipf, E. C.↗