Search NASA⌕ Search

SEARCH · Search NASA

Results for “ABSORPTION SPECTRUM”

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 55 records · Page 3
All sourcesNASA NTRSDOE OSTI
NASA NTRS1977

Ultraviolet absorption spectrum of hydrogen peroxide vapor

The ultraviolet absorption cross sections of hydrogen peroxide vapor have been determined over the wavelength range 210 to 350 nm at 296 K. At the longer wavelengths, the gas phase absorptivities are significantly larger than the corresponding values in condensed phase. The atmospheric H2O2 photodissociation rate for overhead sun at the earth's surface is estimated to be about 1.3 x 10 to the -5th/sec.

Molina, L. T.↗
NASA NTRS1987

Measurement and analysis of the far infrared absorption spectrum of the gaseous mixture H2-CH4

The collision-induced absorption of H2-CH4 mixtures was measured from 20 to 900/cm at 195 and 297 K. By subtracting the absorption due to H2-H2 and CH4-CH4 collisions from that of the mixture, the absorption due to H2-CH4 collisions was obtained. This spectrum was analyzed using the BC model line shape to provide a way of estimating the far-IR spectrum of H2-CH4 for various concentrations of H2 and CH4. Theoretical spectral moments were computed with different potential functions and compared with experimental values.

Birnbaum, George↗
NASA NTRS1982

The anomalous X-ray absorption spectrum of Vela X-1

The HEAO 2 satellite's Solid State Spectrometer and Monitor Proportional Counter was used to observe one orbit of the massive X-ray binary Vela X-1. Using spectral fits to the data as a function of orbital phase, the column density and state of the material along the line of sight to the X-ray source has been inferred. The spectrum near orbital phase 0.2 compares favorably with absorption by neutral material with a column density corresponding to plausible values of stellar wind velocity law and total primary mass loss rate. Spectra at later orbital phases, which show unexpected strong absorption features near 2.0 and 2.5 keV, are interpreted as due to absorption by material with suppressed opacity below 2.0 keV. The opacity required to produce the observed features implies either the presence of an intense soft X-ray flux, or altered elemental abundances in the gas near Vela X-1.

Kallman, T. R.↗
NASA NTRS1992

The ultraviolet absorption spectrum of the quasar H1821+643 (z = 0.297)

High resolution UV observations of the nearby luminous quasar H1821+643 are reported. A complete sample of 38 absorption lines has been constructed. There are five strong extragalactic Ly-alpha absorption lines in the spectrum, all with observed equivalent widths greater than 0.45 A. The local number density of Ly-alpha systems with rest equivalent widths larger than 0.32 A is estimated to be 13 +/- 5 Ly-alpha lines per unit redshift. Some of the Ly-alpha systems with redshifts significantly different from the quasar appear to be associated with galaxies or with clusters of galaxies. Two of the Ly-alpha lines have the same redshift within 400 km/s as that of an emission-line galaxy located at a projected separation from the quasar of about 90 kpc. One of the Ly-alpha systems in H1821+643 occurs at an a absorption redshift approximately equal to the emission-line redshift of the quasar and is accompanied by absorption from the C IV and of VI doublets; this is an example of associated absorption for large-redshift quasars.

Bahcall, John N.↗
NASA NTRS1993

Rotational structure in the near-infrared absorption spectrum of ozone

The lowest energy members of the near-IR absorption bands of ozone possess fine structure which is probably due to the rotation of the molecule in the upper vibronic state, suggesting that this state is metastable. A preliminary analysis of the structures as rotational subbands supports a recent theoretical assignment of the near-IR vibronic features to the 3A2 - 1A1 electronic transition. A binding energy of about 0.1 eV is inferred from the breakoff in the observed structure.

Anderson, Stuart M.↗
NASA NTRS1975

Optical absorption components of light-modulated absorption spectrum of CdS

The amplitude and decay coefficient of light-induced modulation of absorption (LIMA) was measured as a function of wavelength from 535 to 850 nm for single-crystal CdS. The decay coefficient exhibited a discontinuous resonance at 710 nm which was due to the overlap and cancellation of two opposing absorption changes. A method was developed to separate these opposing absorption changes using the measured decay coefficients. The discrete-level-to-band energy for one absorption change was found to be 1.64 eV. An improved model was developed which contains two associated levels in the band gap separated by 0.32 eV.

Conway, E. J.↗
NASA NTRS1970

Ni L self-absorption spectrum

Ni L alpha X ray emission line shape and position as function of bombarding electron energy, observing differential self absorption in anode

Chopra, D.↗
NASA NTRS1981

Investigation of the 1-0 pressure-induced vibrational absorption spectrum of hydrogen at temperatures below ambient

A theoretical fit has been made to laboratory measurements of the 1-0 collisionally induced H2 absorption band over a temperature range of 100-273 K and for densities up to 22 amagats. Both the Birnbaum-Cohen and the MacTaggert-Hunt line shape profiles were used. In addition, an intermolecular potential of either a Lennard-Jones 6-12 or a Morse-spline-van der Waals has been used for each line shape. The best fit resulted in a chi-square of 5%. Line widths have also been derived as a function of temperature. The lifetimes of the states were calculated.

Goorvitch, D.↗