Vacuum-ultraviolet spectrum, molecular

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). 

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). 

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... 

CO has been detected in the interstellar absorption spectrum of f Ophiuchi and has thus become the second interstellar molecule to be detected by rocket ultraviolet spectroscopy. Smith and Stecher (1971) have detected eight transitions in the fourth positive system of 12C160 and four of 13C160, which yielded a 12C/13C ratio of 105. It seems likely that interstellar molecular detections in the vacuum ultraviolet will follow, especially of polyatomic molecules like H20. 

The electronic spectra of the five-membered ring compounds have been intensively studied by the experimental and theoretical works. These molecules are fundamental units in many important biological systems. Furthermore, their excitation spectra are benchmark examples for theoretical studies of molecular excited states [51,55-58]. For furan and thiophene, various types of excitation spectra were measured the vacuum ultraviolet (VUV) spectrum, electron energy-loss (EEL) spectrum and magnetic circular dichroism (MCD) spectrum. The SAC-Cl method offered consistent interpretations of these electronic spectra [51-53]. 

The availability of tunable lasers in the visible and infrared wavelength regions has made possible significant advances in atomic and molecular spectroscopy. At the present time, however, there is a lack cjf lasers and especially of tunable lasers in the ultraviolet (UV), vacuum ultraviolet (VUV, from 200 to 100 nm), and extreme ultraviolet (XUV, I from 100 to ZO nm) regions of the spectrum. In fact, only a few lasers have been made to operate at these short wavelengths, in spite of considerable efforts being made in the past decade. The excimer lasers, such as XeF (315 nm), XeCl (308 nm), KrF (248 nm), ArF (193 nm), Xe2 ( 170 nm), and Ara ( 120 nm), and the H2 laser ( llO nm) have been available for some time now, but these emit at discrete wavelengths or are tunable only over their relatively narrow band-widths. 

Fig. 9 OMT bands for NiOEP, associated with transient reduction (1.78 V) and transient oxidation (—1.18 V). Data obtained from a single molecule in a UHV STM. The ultraviolet photoelectron spectrum is also shown, with the energy origin shifted (by the work function of the sample, as discussed in [25]) in order to allow direct comparison. The highest occupied molecular orbital, n, and the lowest unoccupied molecular orbital, %, are shown at their correct energy, relative to the Fermi level of the substrate. As in previous diagrams,

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