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Vacuum ultraviolet spectrum

The vacuum-ultraviolet spectrum of P406 149) shows two bands at —48900 cm-1 and 63900 cm-1, the first of which exhibits a low-energy shoulder. By analyzing the energies of these bands with respect to the symmetry of the molecule, they can be assigned to fully allowed XAX -> T2 transitions (mainly involving orbital transitions 512 - 3e and 2tx —> 3e, respectively). The experimentally obtained data are reproduced by extended Hiickel and ab initio SCF calculations. [Pg.362]

The molecule is pyramidal, having C3v symmetry with the nitrogen atom at the apex. The molecular dimensions have been determined by electron diffraction (266) and by microwave spectroscopy (161,271). The molecule with this symmetry will have four fundamental vibrations allowed, both in the infrared (IR) and the Raman spectra. The fundamental frequency assignments in the IR spectrum are 1031, vt 642, v2 (A ) 907, v3 (E) and 497 cm-1, v4 (E). The corresponding vibrations in the Raman spectrum appear at 1050, 667, 905, and 515 cm-1, respectively (8, 223, 293). The vacuum ultraviolet spectrum has also been studied (177). The 19F NMR spectrum of NF3 shows a triplet at 145 + 1 ppm relative to CC13F with JNF = 155 Hz (146, 216, 220,249, 280). [Pg.142]

In view of the diverging results it is perhaps worth pointing out that there is a possibility of reinterpreting the vacuum ultraviolet spectrum in terms of a bent form of the radical... [Pg.39]

ABSTRACT. Recent work on radiative processes and collisional excitation in molecular Hydrogen and its deuterated isotopic substitute and in molecular Carbon is reviewed. Particular attention is drawn to non-adiabatic coupling effects on the intensities of Lyman and Werner band systems of the vacuum ultraviolet spectrum of Hj and to the role of nuclear spin on ortho-para transitions in Hj due to collisions. The inter-relation between those processes and state to state chemistry is stressed out. We discuss the implications of these new data in a recent comprehensive model of diffuse interstellar clouds (Viala et al., 1987). [Pg.73]

NON ADIABATIC EFFECTS ON TOE INTENSmES OF LYMAN AND WERNER BAND SYSTEMS OF TOE VACUUM ULTRAVIOLET SPECTRUM OF Hj. [Pg.74]

Osborne, B.A., Marston, G., Kaminski, L., Jones, N.C., Gingell, J.M., Mason, N.J., Walker, I.C., Delwiche, J., Hubin-Franskin, M.-J. Vacuum ultraviolet spectrum of dinitrogen pentoxide. J. Quant. Spectrosc. Radiat. Transf. 64, 67-74 (2000)... [Pg.160]

Jager, M., H. Heydtmann, and C. Zetzsch (1996), Vacuum ultraviolet spectrum and quantum yield of the 193 nm photolysis of phosgene, Chem. Phys. Lett., 263, 817-821. [Pg.1429]

Fig. 2 Vacuum-ultraviolet spectrum of gaseous N2H2. Vibrational assignments show progressions in v 2 and V3. Long progressions belong to v 2 (from [9]). Fig. 2 Vacuum-ultraviolet spectrum of gaseous N2H2. Vibrational assignments show progressions in v 2 and V3. Long progressions belong to v 2 (from [9]).
This teclnhque can be used both to pennit the spectroscopic detection of molecules, such as H2 and HCl, whose first electronic transition lies in the vacuum ultraviolet spectral region, for which laser excitation is possible but inconvenient [ ], or molecules such as CH that do not fluoresce. With 2-photon excitation, the required wavelengdis are in the ultraviolet, conveniently generated by frequency-doubled dye lasers, rather than 1-photon excitation in the vacuum ultraviolet. Figure B2.3.17 displays 2 + 1 REMPI spectra of the HCl and DCl products, both in their v = 0 vibrational levels, from the Cl + (CHg) CD reaction [ ]. For some electronic states of HCl/DCl, both parent and fragment ions are produced, and the spectrum in figure B2.3.17 for the DCl product was recorded by monitoring mass 2 (D ions. In this case, both isotopomers (D Cl and D Cl) are detected. [Pg.2083]

Usually, the ultraviolet and visible regions of the spectrum are recorded. Many of the most intense emission lines lie between 200 nm and 400 nm. Some elements (the halogens, B, C, P, S, Se, As, Sn, N, and O) emit strong lines in the vacuum ultraviolet region (170-200 nm), requiring vacuum or purged spectrometers for optimum detection. [Pg.636]

P-Hydroxy-A-norpregn-3(5)-en-2-one (7) A solution of the hydroxy-methylene steroid (5) (24.8 g) dissolved in 240 ml of acetic acid and 240 ml of ethyl acetate is ozonized at — 10° with one molar equivalent of ozone. The resulting solution is diluted with 240 ml. of water and 60 ml of 30 % hydrogen peroxide and allowed to stand overnight. The solution is diluted with 1.5 liters of water and extracted with 3 x 700 ml portions of ethyl acetate. The combined extracts are washed with water, saturated sodium chloride solution, dried over sodium sulfate and concentrated to dryness under vacuum, leaving 23.4 g of a colorless amorphous residue of crude diacid. This material shows a maximum in the ultraviolet spectrum at 224 mp (s 6,400) indicating a 53 % yield of unsaturated acid (6). It is used without further purification. [Pg.411]

The useful spectral range is usually found between 700 and 200 nm. (The region below 200 nm is the vacuum ultraviolet, which requires special instrumentation and, for this reason, is less important.) The spectrum is the result of measuring the absorption of light versus wavelength. The position of the absorption maximum (wavelength = peak position), is important, as is related to the amount of radiation absorbed (molar absorptivity, e). [Pg.71]

Production of strand breaks by very low energy electrons (5-25 eV) in thin solid DNA films using ultrahigh vacuum systems have been reported in a number of studies [107-109]. Such studies have demonstrated the efficiencies of low energy electrons and photons to induce DNA damage. In the vacuum ultraviolet (UV) region, examination of experimental data [86,110,111] shows that the induction of strand breaks depends on the absorption spectrum of the components in the medium and the sensitivity spectrum of DNA [112]. Introduction of a variable with the wavelength for the induction of SSB by OH radicals, in conjunction with a fixed value for the quantum efficiency for the production of OH radical (sensitivity spectrum for induction of SSB in aqueous system [112]. [Pg.504]

Br(42Pi/2) being rapidly quenched by any Br2 present.76 While Cl(32iVt) would be expected from the photolysis of Cl2, the strongest absorption transition of the excited atom at 1351.7 A (Table IV) was obscured by the molecular spectrum of undissociated Cl2 and only an absorption transition of the ground state atom at 1335.7 A (Table IV) could be detected through a window in the vacuum ultraviolet molecular spectrum.29... [Pg.26]


See other pages where Vacuum ultraviolet spectrum is mentioned: [Pg.190]    [Pg.237]    [Pg.80]    [Pg.6]    [Pg.7]    [Pg.190]    [Pg.54]    [Pg.35]    [Pg.162]    [Pg.190]    [Pg.237]    [Pg.80]    [Pg.6]    [Pg.7]    [Pg.190]    [Pg.54]    [Pg.35]    [Pg.162]    [Pg.1330]    [Pg.402]    [Pg.300]    [Pg.562]    [Pg.71]    [Pg.159]    [Pg.10]    [Pg.70]    [Pg.133]    [Pg.35]    [Pg.10]    [Pg.32]    [Pg.71]    [Pg.181]    [Pg.11]    [Pg.736]    [Pg.823]    [Pg.71]    [Pg.10]   
See also in sourсe #XX -- [ Pg.336 ]




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Vacuum-ultraviolet spectrum, molecular

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