W. H. Parkinson

High resolution absorption cross section measurements and band oscillator strengths of the (1, 0)−(12, 0) Schumann-Runge bands of O2

Abstract Cross sections of O 2 at 300 K have been obtained from photoabsorption measurements at various pressures throughout the wavelength region 179.3–201.5 nm with a 6.65 m photoelectric scanning spectrometer equipped with a 2400 lines mm −1 grating and having an instrumental width (FWHM) of 0.0013 nm. The measured absorption cross sections of the Schumann-Runge bands (12, 0) through (1, 0) in this wavelength region are absolute, i.e., independent of the instrumental width, a result not achieved previously. The measured cross sections are presented graphically and are available at wavenumber intervals of > sim; 0.1 cm −1 as numerical complications stored on magnetic tape from the National Space Science Data Center, NASA/Goddard Space Flight Center, Greenbelt, MD 20771, U.S.A. Band oscillator strengths of the (12, 0) through (1, 0) bands have been determined by direct numerical integration of the measured cross sections.

Absorption cross section measurements of carbon dioxide in the wavelength region 118.7–175.5 nm and the temperature dependence

Abstract Laboratory measurements of the relative absorption cross sections of CO 2 at the temperatures 195 and 295 K have been made throughout the wavelength region 118.7–175.5 nm. Laboratory measurements of the absolute absorption cross sections of CO 2 at the temperature 195 and 295 K have been made at 12 different wavelengths in the region 118.7–175.5 nm. These absolute values have been used to put the relative cross section measurements of CO 2 at 195 and 295 K on an absolute basis throughout the region 118.7–175.5 nm. Almost no temperature dependence was observed in the peak cross sections of the strong bands at 130 nm region, but large temperature effects are seen in the other regions.

High resolution absorption cross sections in the transmission window region of the Schumann-Runge bands and Herzberg continuum of O2

Abstract The absorption cross sections of the Schumann-Runge bands in the window region between the rotational lines have been measured in the wavelength region 180–195 nm. The measurements have been done with many different pressures of oxygen, 2.5−760 torr, so that the pressure-dependent absorption can be separated from the main cross sections. The published cross sections [Yoshino et al. . Planet. Space Sci. 31 , 339 (1983)] in the window region are superseded by the present cross sections. The combined cross sections are presented graphically here and are available at wavenumber intervals of 0.1 cm −1 as numerical compilations stored on magnetic tape, from the National Space Science Data Center, NASA/ Goddard Space Flight Center, Greenbelt, MD 20771, U.S.A. The Herzberg continuum cross sections are derived after subtracting calculated contributions from the Schumann-Runge bands and are significantly smaller than any previous measurements.

High resolution absorption cross-section measurements of ozone at 195 K in the wavelength region 240–350 nm

Cross-sections of the Hartley-Huggins bands of 03 at the temperature 195 K have been obtained from photoabsorption measurements at column densities in the range 2 × 1017−1 × 1021 cm−2 throughout the wavelength region 240–350 nm with a 6.65 m photoelectric scanning spectrometer equipped with a 2400 lines mm−1 grating and operated at an instrumental width (FWHM) of 0.003 nm. The assumptions made in putting the measured relative cross-sections on an absolute basis are discussed. Fine structure in the cross-section observed in the Huggins bands is illustrated in the region 323–327 nm where shallow features of width 0.01–0.02 nm occur superposed on a stronger apparent continuum exhibiting broader wavy structure.

Atlas of the Schumann–Runge Absorption Bands of O2 in the Wavelength Region 175–205 nm

After a critical summary of previous wavelength measurements and rotational line assignments of the Schumann–Runge absorption bands of O2, the results of the present study performed at high resolution with a 6.65 m vacuum spectrograph are given. These include (a) an atlas of the Schumann–Runge absorption bands of O2 at 300 K showing detailed rotational line assignments in the wavelength region 175–205 nm containing the bands (v′,0) with v′=0–21 and (v′,1) with v′=2–16; (b) tables of wave numbers measured for rotationally assigned principal branch lines belonging to the bands (v′,0) with v′=0–17 and (v′,1) with v′=2–17; (c) a table of measured wave numbers of lines in the region near the dissociation limit where many unassigned lines exist; (d) a table of wave numbers calculated for satellite and forbidden lines belonging to the bands (9,0)–(17,0) together with the few values obtained from our measurements; and (e) a table of term values for the upper state B 3Σ−u vibration–rotation levels with v′=9–17 cal...

High resolution absorption cross section measurements of SO2 at 213 K in the wavelength region 172–240 nm

Abstract Laboratory measurements at high resolution of the absorption cross section of SO2 at the temperature 213 K have been performed in the wavelength region 172–240 nm with a 6.65 m scanning spectrometer/spectrograph operated at an instrumental width of 0.002 nm. The measured cross sections are presented graphically in representative wavelength regions and are available throughout the region 172–240 nm at wavenumber intervals of 0.4–0.1 cm−1 as a numerical tabulation stored on magnetic tape from the National Space Science Data Center, NASA/Goddard Space Flight Center, Greenbelt, MD 20771, U.S.A. The measured cross sections, which are relevant to the photochemistry of planetary atmospheres, possess significantly more spectroscopic structure, and are more accurate, than previous measurements made at lower resolution.

Molecular spectroscopic constants of O2(B3Σu−): The upper state of the Schumann-Runge bands

Abstract Spectroscopic constants of the B3Σu− state of O2 for 0 ≤ v′ ≤ 17 have been determined from the experimental data of K. Yoshino, D. E. Freeman, and W. H. Parkinson [J. Phys. Chem. Ref. Data 13, 207–227 (1984)] on the high-resolution absorption spectrum of the Schumann-Runge bands. The effective spin-spin parameters, λ, and spin-rotation constants, γ, have been expressed in power series of ( v′ + 1 2 ) for the levels with v′ = 0−2, 7, 9−12, which correspond to bands with partially or fully resolved triplet structure. Values of λ and γ have been obtained by interpolation for the levels with v′ = 3−6, 8, which correspond to bands with unresolved triplet structure. Comparison is made with previous determinations of the spectroscopic constants.

Absolute absorption cross section measurements of CO2 in the wavelength region 163–200 nm and the temperature dependence

Abstract Laboratory measurements of the absorption cross section of CO 2 at the temperatures 195 and 295 K have been made throughout the wavelength region 163–200 nm by using a high resolution grating spectrometer. Cross sections at 195 K are smaller than those at 295 K, and the band structures are more emphasized as expected. In combining with our previous measurements [J. Quant. Spectrosc. Radiat. Transfer, 55 (1996) 53], the absorption cross sections of CO 2 are available in the wavelength region 117.8–200.0 nm at 295 K and 117.8–192.5 nm at 195 K.

The extreme-ultraviolet spectrum of a solar active region.

Extreme-ultraviolet spectra (280-1370 A) of the brightest point in McMath Region 10266 and of the quiet solar atmosphere are presented as measured by the Harvard scanning spectrometer on OSO-6. Line identifications and physical parameters of the active region are discussed. (auth)

Predissociation linewidths of the (1,0)-(12,0) Schumann-Runge absorption bands of O2 in the wavelength region 179-202 nm

A nonlinear least‐squares method of retrieving predissociation linewidths from the experimental absolute absorption cross sections of Yoshino et al. [Planet. Space Sci. 31, 339 (1983)] has been applied to the (1,0)–(12,0) Schumann–Runge bands of oxygen. Predissociation linewidths deduced for the Schumann–Runge bands are larger than the theoretical predictions of Julienne [J. Mol. Spectrosc. 63, 60 (1976)] and the latest measurements of Lewis et al. [J. Quant. Spectrosc. Radiat. Transfer 36, 187 (1986)]. The larger linewidths found will have an impact on calculations of solar flux penetration into the Earth’s atmosphere and of the photodissociation rates of trace species in the upper atmosphere. Systematic variation of predissociation linewidths with rotational quantum number is observed in the bands (v’,0) with v’=6, 8, 9, 11, and 12.