Far ultraviolet

Ultraviolet and visible spectra arise from transitions between the electronic states in molecules. The terms electronic spectra and ultraviolet and visible spectra are synonymous and cover the range 200-800 mp.. The far-ultraviolet region 100-200 mp, only partially transmitted by quartz and appreciably absorbed by air, will not be considered. 

Radio TV Microwave Millimetre wave Mid-infrared Near- infrared Visible Near- ultraviolet Far- ultraviolet X-ray Y-ray... 

Far-ultraviolet Microwave discharge in noble gases Lyman discharge LiF (or no windows) Grating Photomultiplier photodiode photographic plate... 

Transient species, existing for periods of time of the order of a microsecond (lO s) or a nanosecond (10 s), may be produced by photolysis using far-ultraviolet radiation. Electronic spectroscopy is one of the most sensitive methods for detecting such species, whether they are produced in the solid, liquid or gas phase, but a special technique, that of flash photolysis devised by Norrish and Porter in 1949, is necessary. 

Promotion of an electron in Hc2 from the (7 15 to a bonding orbital produces some bound states of the molecule of which several have been characterized in emission spectroscopy. For example, the configuration ((J l5 ) ((7 l5 ) ((7 25 ) gives rise to the 2i and bound states. Figure 7.24(a) shows the form of the potential curve for the state. The A-X transition is allowed and gives rise to an intense continuum in emission between 60 nm and 100 nm. This is used as a far-ultraviolet continuum source (see Section 3.4.5) as are the corresponding continua from other noble gas diatomic molecules. 

Fig. 6. The far ultraviolet rotatory dispersion of native calf skin collagen - in 0.01 molar acetic solution. The ultraviolet rotatory dispersion of the same preparation of calf skin collagen heated at 50 °C for 30 min, coded to 25 °C and measured immediately, O-O-O. Concentrations were between 0.0076 and 0.076%. Data from Blout et al.18a)...

Fig. 7. The far ultraviolet rotatory dispersions of poly-L-proline II and L-proline 0-0-0 in...

Direct photochemical reactions in the stratosphere induced by far ultraviolet solar light are well known to be important for the chemistry of the atmosphere. However, only a small fraction of the solar energy flux is in this spectral region. 

Paramagnetic Species of Biological Interest (Ehrenberg). Photoprotection from Far Ultraviolet Effect in Cells 7 602... 

Fig. 10. (A) Far-ultraviolet CD spectra of fragment 206-316 of thermolysin at different temperatures in 20 raM Tris-HCl buffer, pH 7.2. Numbers near the curves indicate temperature in degrees Celsius. The peptide concentration was 0.2 mg/ml. (B) Temperature dependence of [0]/[0]o at 220 nm of fragment 206-316, where [0]o is the mean residue ellipiticity at 22°C. Reprinted with permission from Peptides Proceedings of the Fifth American Peptide Symposium, John Wiley Sons, Inc., 1977. Copyright by John Wiley Sons, Inc.

FUSE (Far Ultraviolet Space Explorer) combs the sky in search of the spectra of hot bright background objects (quasars and stars) modified by absorption lines due to interposed clouds (both extragalactic and interstellar). Its main prey is deuterium, an atom of major cosmological significance. It shonld also establish a detailed breakdown of interstellar gases. FUSE is a NASA project with French participation. ... 

Ausloos, P. Lias, S.G. Far ultraviolet photochemistry of organic compunds. In Chemical Spectroscopy and Photochemistry in the Vacuum Ultraviolet, Sandorfy, C. Ausloos, P. Robin, M.B., Eds. Chemical Spectrospy and Photochemistry in Vacuum Ultraviolet Reidel Dordecht, 1974 Vol. 8, Ser. 6, 465 pp. 

Huebert, B. J., and R. M. Martin, Gas-Phase Far-Ultraviolet Absorption Spectrum of Hydrogen Bromide and Hydrogen Iodide, J. Phys Chem., 72, 3046-3048 (1968). 

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