Search results for "Bromine"
showing 10 items of 102 documents
The hyperfine structure in the rotational spectra of bromofluoromethane: Lamb-dip technique and quantum-chemical calculations
2008
International audience; The hyperfine structure in the rotational spectra of six isotopic species of bromofluoromethane, namely CH2{79}BrF, CH2{81}BrF, CDH{79}BrF, CDH{81}BrF, CD2{79}BrF, and CD2{81}BrF, has been investigated using the Lamb-dip technique in the submillimeter-wave frequency range. Measurements as well as assignment procedures have been supported by high-level quantum-chemical calculations of the hyperfine parameters at the coupled-cluster level. For all species, the accuracy of the determined rotational and centrifugal distortion constants as well as the bromine quadrupole-coupling constants have been improved with respect to available literature data, whereas the full bromi…
<title>Iodine and bromine resonance lamps in atmospheric research</title>
2003
For the first time previously developed iodine resonance spectra source has been tested in flash photolysis experiment. Quantitative measurements of concentration kinetics of iodine atomic species in a I2+O3 system are possible. The 183.038 nm resonance absorption transition of I(2P3/2) in previously developed EDL has been studied; dependence of self-absorption and self-reversal on iodine partial pressure in the discharge volume has been measured. The search for optimal conditions for an iodine EDL with minimized self-absorption and sufficient intensity were made. In condition of flash photolysis with previously described method it is possible to determine the emission temperature, oscillat…
Determination of Cl/C and Br/C ratios in pure organic solids using laser-induced plasma spectroscopy in near vacuum ultraviolet
2004
Several solid organic compounds containing bromine and chlorine were analyzed with laser-induced plasma spectroscopy. Emission lines were detected in the near vacuum ultraviolet spectral region by using a gas-purged spectrograph and an intensified charge-coupled device detector. The performance of this setup in the determination of the halides in the organic samples was evaluated. Carbon emission lines in the near vacuum ultraviolet were used as internal standards for the measurement of chlorine and bromine. Linear correlation was found between the carbon and halogen emission signal ratio and the corresponding atomic ratio of the compound.
Insight into the mechanism of diazocompounds transformation catalyzed by hetero cuboidal clusters [Mo3CuQ4(MeBPE)3X4]+, (Q=S, Se; X=Cl, Br): The cata…
2008
Abstract Two enantiomerically pure trinuclear compounds of formula (P)-[Mo3S4{(R,R)-Me–BPE}3Br3]Br and (P)-[Mo3Se4{(R,R)-Me–BPE}3Cl3]Cl, (P)-1b.Br and (P)-1c.Cl, respectively, have been synthesized in a good yield and a stereospecific manner by excision of polymeric [Mo3Q7X4]n (Q = S or Se, X = Cl or Br) phases with (R,R)-Me–BPE{1,2-bis[(2R,5R)-2,5-(dimethylphospholan-1-yl)]ethane}. They have been transformed into chiral hetereo cuboidal compounds [Mo3S4{(R,R)-Me–BPE}3Br3]PF6, (P)-2b.PF6, and [Mo3Se4{(R,R)-Me–BPE}3Cl3]PF6, (P)-2c.PF6, by reaction with copper salts. All these compounds have been characterized by 31P NMR, IR, UV–Vis, mass spectrometry, elemental analysis, and chiral dichroism…
Ageing of Dissolved Halogenated Humic Substances and the Microbiological Influence on this Process
2000
The distribution of halogens in various fractions of humic substances (HS), separated by their molecular weight, was found to be different for the different halogens. This was demonstrated for chlorine, bromine, and iodine in sewage and brown water samples by applying inductively coupled plasma mass spectrometry coupled with size-exclusion chromatography. Quantification of the different fractions of iodinated humic substances was obtained by quadrupole mass spectrometry in connection with the isotope dilution technique using an 129I-enriched spike solution. Quantitative analysis was not possible for the corresponding chlorine and bromine species because of spectrometric interferences in the…
Matrix isolation studies and DFT calculations on molecular alkali metal bromates
2009
DFT and MP2 calculations have been carried out on a series of molecular alkali metal bromates MBrO3 (M = Na, K, Rb, Cs), and the results compared with matrix isolation IR studies on the vaporisation of the solid salts. For M = Na, K or Rb, no ternary molecular species were detected in the low temperature matrix, but vaporisation of solid caesium bromate at 730 K resulted in the formation of molecular CsBrO3, which was identified as having a C3v structure involving tridentate coordination. Additionally, the DFT and MP2 calculations provide estimates of the molecular parameters for all four MBrO3 species, and for the related MXO3 species CsClO3 and CsIO3. The proven stability of MBrO3 molecul…
New phosphathiamacrocycles containing polypypiridine units
2006
Abstract A new 2,2′-bipyridine-based phosphadithiamacrocycle: 3,3′-5-phenyl-2,8-dithia-5-phospha[9]-2,2′-bipyridinophane (L) has been synthesized by reacting 6,6′-bis(bromomethyl)-2,2′-bipyridine and dilithium 3-phenyl-3-phosphapenta-1,5-dithiolate. The phosphoryl derivative: 3,3′-5-oxo-5-phenyl-2,8-dithia-5-phospha[9]-2,2′-bipyridinophane (Lox) synthesized by direct oxidation of L at open atmosphere. Both compounds have been isolated as white solids containing different amounts of LiBr. The reaction of acetonitrile solutions of these solids with Fe(II) perchlorate gave the complexes [FeBr(L)](ClO4) · 2H2O and [FeBr(Lox)](ClO4) · 3H2O, which were crystallized as [FeBr(L)]Br · H2O and [ FeBr…
XAFS Studies of High-Valent Porphyrinato Manganèse Complexes with Ozone
1997
We produce strong evidence of the interaction of ozone with a series of Manganese (III) porphyrinato complexes to form a well defined reactive intermediate. In the latter species, the Manganese atom which is formally in a tetravalent (IV) state, is (at least) hexacoordinated with the metal unambiguously lying in the basal plane of the four pyrrolic nitrogens of the porphyrin macrocycle. Substitution of Bromine or Chlorine axial ligands by ozonids is most likely to happen. This conclusion is also supported by XANES and EXAFS spectra recorded at the Chlorine K-edge which suggest that ozone may even form with chlorine a complex anion.
Halogen diffusion in a basaltic melt
2007
Abstract The diffusion of the halogens fluorine, chlorine and bromine was measured in a hawaiitic melt from Mt. Etna at 500 MPa and 1.0 GPa, 1250 to 1450 °C at anhydrous conditions; the diffusion of F and Cl in the melt was also studied with about 3 wt% of dissolved water. Experiments were performed using the diffusion-couple technique in a piston cylinder. Most experiments were performed with only one halogen diffusing between the halogen-enriched and halogen-poor halves of the diffusion couple, but a few experiments with a mixture of halogens (F, Cl and Br) were also performed in order to investigate the possibility of interactions between the halogens during diffusion. Fluorine and chlor…
Direct determination of halogens in powdered geological and environmental samples using isotope dilution laser ablation ICP-MS
2005
Abstract Laser ablation inductively coupled plasma isotope dilution mass spectrometry (LA-ICP-IDMS) with a special laser ablation system for bulk analyses (LINA-Spark™-Atomiser) was applied for direct determinations of chlorine, bromine, and iodine in rock and sediment samples. Special attention was focused on possible inter-halogen fractionations and analyte/spike isotope fractionations by using LA-ICP-MS and LA-ICP-IDMS, respectively. A variation of Br/Cl and I/Cl element intensity ratios by a factor of 1.3–3 was observed when changing the nebulizer gas flow rate in the range of 0.84–1.0 L min−1 and the laser power density in the range of 2–10 GW cm−2, respectively. When using an internal…