نتایج جستجو برای: uv absorption
تعداد نتایج: 195475 فیلتر نتایج به سال:
[1] Nitrogen trifluoride (NF3) is an atmospherically persistent greenhouse gas that is primarily removed by UV photolysis and reaction with O(D) atoms. In this work, the NF3 gas-phase UV absorption spectrum, s(l,T), was measured at 16 wavelengths between 184.95 and 250 nm at temperatures between 212 and 296K. A significant spectrum temperature dependence was observed in the wavelength region mo...
Synthesis of mycosporine-like amino acids (MAAs) can significantly protect phytoplankton cells against damaging ultraviolet (UV) radiation, depending on the concentration, type and cellular distribution of these UV sunscreens. We addressed the hypothesis that MAAs are concentrated around UV-sensitive organelles for improved efficiency, thereby increasing their ‘package effect’. This was investi...
If a gamma ray burst with strong UV emission occurs in a molecular cloud, there will be observable consequences resulting from excitation of the surrounding H 2. The UV pulse from the GRB will pump H 2 into vibrationally-excited levels which produce strong absorption at wavelengths λ 1650Å. As a result, both the prompt flash and later afterglow will exhibit strong absorption shortward of 1650Å,...
We present deep spectropolarimetric observations obtained with the W. M. Keck Telescope of the very high redshift (z=3.79786±0.0024) radio galaxy 4C 41.17. We find that the bright, spatially extended rest-frame UV continuum emission from this galaxy, which is aligned with the radio axis, is unpolarized (P2σ < 2.4%). This implies that scattered AGN light, which is generally the dominant contribu...
Westerbork Radio Synthesis Telescope observations of the redshifted 21cm line absorber against the z em = 0.871 double lobed quasar 3C196 show that the intervening absorber is an L ≈ L * spiral galaxy (3C196-G1) and that the absorbing layer of cold gas extends to radii of at least 30 h −1 50 kpc. The new data solve several long standing puzzles about this system by (1) discovering a second 21cm...
We present a Hubble Space Telescope Space Telescope Imaging Spectrograph spectrum of ASASSN-14li, the first rest-frame ultraviolet (UV) spectrum of a tidal disruption flare (TDF). The underlying continuum is well fit by a blackbody with T 3.5 10 UV 4 = ́ K, an order of magnitude smaller than the temperature inferred from X-ray spectra (and significantly more precise than previous efforts based ...
The compound (n-Bu4N)2Tc2Br8 was prepared by the metathesis of (n-Bu4N)2Tc2Cl8 with HBr (g) in dichloromethane and characterized by X-ray absorption fine structure spectroscopy and UV-vis spectroscopy. Analysis of the data gives a Tc-Tc distance of 2.16(1) A and a Tc-Br distance of 2.48(1) A. The Tc(III) oxidation state was inferred by the position of the edge absorption, which reveals a shift ...
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