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In this Letter, we report the first temperature-dependent measurements (at 295, 373, 473 and 573 K) of the O 2 photoabsorption cross sections at the aeronomically important NI airglow and auroral emission lines (at 1200, 1492 and 1742 A) in the far ultraviolet spectral region. A high-current low-voltage argon mini-arc source was used as the light source in the present measurements. The measurements were carried out at a spectral resolution of 0.30 A at full-width-at-half-maximum (FWHM). Direct application of the Beer-Lambert absorption equation yielded the absolute photoabsorption cross sections for O 2 at each NI emission lines of interest.

An investigation concerning possible visible and UV photon emissions by gas phase C(sub 60) ( and C(sub 70)) samples under electron impact excitation was caried out in the 180-750 nm spectral region. Radiation resembling OH (A (sup 2)pi {leads to}X (sup 2){summation}) emission bands and H Balmer series was observed. Based on our investigations, it is concluded that none of the observed emission was associated with the fullerene molecule itself but with the C(sub 60)OH and C(sub 60)H adducts (which are present in the fullerene samples). We also conclude that in these adducts, simultaneous ionization and excitation take place under electron impact and the excited ionic species (C(sub 60)+OH* and C(sub 60)+H*) decay by radiation which was observed in our experiments. These surprising results reveal an interesting new character of buckyball adducts.

We report the first temperature-dependent measurements (at 295, 373, 473, and 573 K) of the O2 photoabsorption cross sections at the aeronomically-important OI-1304 A triplet emission lines. A high current, low voltage argon mini-arc source was used as the light source. The measurements were carried out at a spectral resolution of 0.5 A at full-width-at-ahlf-maximum (FWHM). Direct application of the Beer-Lambert absorption equation yielded the absolute photoabsorption cross sections for O2 at each line of the OI triplet.

The FUV emission spectrum of xenon, which contains five emission lines at 117.04, 119.2, 125.1, 129.56 and 146.96 nm over the wavelength range 110–160 nm, produced by electron impact at 100 eV is presented. The measurements were obtained under near-optically-thin conditions at a spectral resolution of 1.0 nm FWHM. In addition, the absolute emission cross sections at 100 eV electron impact energy were obtained for these emission lines. Most prominent features of the FUV spectrum are the Xe I lines at 146.9 and 119.2 nm with the emission cross sections of 58.5 × 10−18 cm2 and 45.0 × 10−18 cm2, respectively, with an uncertainty of 27%.

We present the extreme ultraviolet (EUV) emission spectrum of CO_2 induced by electronimpact at 200 eV. There are 36 spectral features which are identified with a resolution of 0.5 nmover the wavelength range of 40 to 125 nm. Absolute emission cross sections were obtained for eachof these features. The EUV emission spectrum induced by electron impact consist of atomicmultiplets of CI,II and OI,II,III as well as CO and CO^+ molecular band systems produced bydissociative excitation. The CI (119.4 nm) multiplet is the strongest feature of CI with a peak crosssection of 3.61 x 10^(-19) cm^2 at 200 eV. The strongest feature of OI in the EUV spectrum is theOI (99.0 nm) multiplet with a peak cross section of 3.59 x 10^(-19) cm^2 at 200 eV.

Electron-impact excitation of CO plays an important role in planetary atmospheres and interstellar clouds. At the present time, serious discrepancies exist among excitation cross sections reported in the literature for this molecule. We measured electron-impact excitation cross sections for B 1 Σ + ← X 1 Σ + , C 1 Σ + ← X 1 Σ + and E 1 Π ← X 1 Σ + states of CO at 100 eV impact energy using electron energy-loss spectroscopy.

Total cross sections have been measured for electron scattering on CH 4 in the 4–300 eV energy range utilizing a linear attenuation technique. The present results are compared with existing experimental data of other groups in this energy range. Generally, a good agreement with other experimental data is found except with those of Barbarito, Basta and Caliechio and Sueoka and Mori. The total electron scattering cross sections below 10 eV are inconsistent with available integral elastic scattering cross sections. It is suggested that the elastic data are in error and should be remeasured.