Iodine spectrum fluorescence

Most of the thiazoles studied absorb in the ultraviolet above 254 nm, and the best detection for these compounds is an ultraviolet lamp (with plates containing a fluorescent indicator). Other indicator systems also exist, among which 5% phosphomolybdic acid in ethanol, diazotized sulfanilic acid or Pauly s reagent (Dragendorff s reagent for arylthiazoles), sulfuric anisaldehyde, and vanillin sulfuric acid followed by Dragendorff s reagent develop alkylthiazoles. Iodine vapor is also a useful wide-spectrum indicator. 

Beattie, I.R., Ozin, G.A., and Perry, R.O., Gas phase Raman spectra of P4, P2, As4 and As2. Resonance fluorescence spectrum of 80Se2. Resonance fluores-cence-Raman effects in the gas-phase spectra of sulfur and iodine. Effect of pressure on the depolarization ratios for iodine,. Chem. Soc., Perkin I, 2071, 1970. 

Soon after Dennison had deduced from the specific-heat curve that ordinary hydrogen gas consists of a mixture of two types of molecule, the so-called ortho and para hydrogen, a similar state of affairs in the case of iodine gas was demonstrated by direct experiment by R. W. Wood and F. W. Loomis.1 In brief, these experimenters found that the iodine bands observed in fluorescence stimulated by white light differ from those in the fluorescence excited by the green mercury line X 5461, which happens to coincide with one of the iodine absorption lines. Half of the lines are missing in the latter case, only those being present which are due to transitions in which the rotational quantum number of the upper state is an even integer. In other words, in the fluorescence spectrum excited by X 5461 only those lines appear which are due to what we may provisionally call the ortho type of iodine molecule. 

The Helium-Neon Laser-Induced Fluorescence Spectrum of Molecular Iodine 14... 

S. Landau and E. Stenz examined the effect of low temp, and dissociation on the fluorescence of iodine vapour at low press. Fluorescence decreases as the temp, is raised, but does not cease at 800°. Dissociation destroys both fluorescence and the resonance spectra. It is therefore inferred that the complex vibrating system is not inherent in the atom, but in the molecule that the structure of the atom is relatively simple and that, in all probability, the absorption lines which are so characteristic of diatomic iodine and so sensitive to the action of monochromatic light, do not belong to the absorption spectrum of monatomic iodine. 

W. Steubing found that the intensity of the fluorescence of iodine vapour is weakened between the poles of a powerful electromagnet. The result has nothing to do with the Zeeman effect, and has no connection with effects produced by admixture with gases, solvents, etc. It is produced by a direct action of the magnetic field on the electrons causing the band spectrum weakening the individual vibrations. 

The primary process in the vacuum ultraviolet photolysis of methylene iodide has been studied by Style and Ward,12 who observed that irradiation with light of wavelength 1250-2000 A. excites the fluorescence spectrum of iodine. Attempts to observe any appreciable delay between light absorption and fluorescence were unsuccessful, and the intensity of fluorescence was directly proportional to the light intensity and the pressure of methylene iodide. It was concluded that the excited I2 was produced in the primary process,... 

Substitution in aromatic hydrocarbon naturally shifts the wavelength of fluorescence in agreement with the effect of the same substitution on the absorption spectrum. Alkyl substitution has little effect. Chlorine and bromine weaken the florescence and iodine completely inhibits it. The simplest aromatic heterocyclics, pyridine, pyrrole, furan and thiophene do not show fluorescence. 

Fig. 19. Resonant scattering, absorption and fluorescence of iodine in a 100 pm foil of polyacetylene, CHJ j, near the Lj-absorption edge (X = 2.72 A) at h = 0.1 The very high dispersion of fluorescence and absorption at the short wavelength side of the absorption edge limits the measurement of resonance scattering to the pre-edge region of the spectrum. ( + ) f (E) S,...

Figure 1 Fluorescence spectrum from two-photon excitation of molecular iodine. Top spectrum obtained at ten times sensitivity of bottom. - S transition in fluorescence excited by laser at 28 514 cm-1...

Examples of such studied systems are Cu/Au(lll), Ag/Au(lll), Pb/ Ag(l 11), Cu/Pt(l 11)/I. The fluorescence spectrum of Cu/Pt( 111 )/I detected in situ by X-ray absorption (Figure P. 8) shows a half of copper layer on the face (111) - the face that unites three opposite diagonal comers in a cube, while the monocrystal Pt is used as an electrode within iodine vapor. 

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