Showing papers by "Lester Andrews published in 1989"

Oxidation of phosphorus(III) halides by red photolysis of ozone complexes in solid argon

Abstract: PCl{sub 3}-O{sub 3} and PBr{sub 3}-O{sub 3} complexes in solid argon photolyze to give phosphoryl halides with red visible radiation that has no effect on isolated ozone. These observations and similar results for PH{sub 3}-O{sub 3} and P{sub 4}-O{sub 3} complexes show that the complex markedly increases the cross section for red photodissociation of ozone and suggest that this increase is due to the complex effectively lowering the barrier to dissociation by providing a strongly exothermic dissociation-recombination process.

Absorption spectra of the phosphorus oxide (PO2 and PO3) radicals in solid argon

Abstract: Observation de nouveaux systemes de bandes electroniques dans l'argon solide a 695 et 300 nm. La bande dans le rouge est attribuee a PO 3 sur la base de comparaisons avec les especes isoelectroniques NO 3 et SO 3 + et de deplacements isotopiques. Le systeme de bandes dans l'UV est attribue a PO 2 en accord avec des positions de bandes d'absorption et d'excitation en phase gazeuse, avec des intervalles vibroniques et avec des deplacements isotopiques

Infrared spectra of arsine-ozone complexes, reaction products, and photolysis products in solid argon

Abstract: Codeposition of AsH{sub 3} and O{sub 3} at high dilution in argon gave a large yield of AsH{sub 3}-O{sub 3} complex and a small yield of reaction products identified as cis- and trans-H{sub 2}AsOH. The complex photolyzed with red light, which showed that a specific interaction within the complex markedly increased the red photodissociation probability for the O{sub 3} submolecule. The red photolysis products were H{sub 3}AsO, H{sub 2}AsOH, and an intermediate species tentatively identified as HAsO. Further blue and near-UV irradiations destroyed HAsO and produced HOAsO{sub 2}. This AsH{sub 3} and O{sub 3} study parallels earlier PH{sub 3} work and shows that AsH{sub 3} is slightly more reactive than PH{sub 3} with O{sub 3}.

Infrared spectra of isotopic (HCl) 3 clusters in solid neon

Abstract: The codeposition of Ne/HCl mixtures at 5 K leads to the formation of a large yield of (HCl)3 which exhibits one sharp fundamental at 2801.5 cm−1 with chlorine isotopic splittings at 2800.2 and 2799.4 cm−1. Deuterium substitution gives rise to the three stretching fundamentals for (HCl)2(DCl) and (HCl)(DCl)2 with resolved chlorine isotopic splittings that identify these clusters. The neon matrix observations confirm the argon matrix assignments and characterization of (HCl)3 as a C3h cyclic species by the Perchard group and predict a strong gas phase band at 2816±3 cm−1.

Matrix infrared study of low-energy electron impact on hydrocarbons

Abstract: Utilisation de la spectrometrie d'absorption IR pour l'etude du processus d'impact electronique sur des melanges gazeux d'argon et d'hydrocarbure. Observation de nombreux fragments neutres

Chemical ionization of chloromethanes for matrix isolation spectroscopy

Abstract: A chemical ionization source from mass spectrometry has been used with CCl 4 , CHCl 3 and CH 2 Cl 2 /argon mixtures for matrix isolation spectroscopy in the IR and visible-near UV regions. The major product absorptions in both regions have been observed and assigned previously. The comparison of positive and negative ion operation is striking for CCl 4 ; the yields of CCl + 3 , CCl + 4 and Cl + 3 are increased and HCl − 2 is not produced in positive ion operation.

Infrared spectra of the tetraarsenic-ozone reaction and photolysis products in solid argon

Abstract: As 4 and O 3 codeposited with excess argon at 14-17 K produced new sharp weak bands at 921.7, 590.3, and 565.4 cm −1 that increased with red-light photolysis. In the early stages of 630-1000-nm irradiation, the upper band was favored, but in later stages the upper band decreased while the lower bands increased. These single O atom species are assigned to AsO complex and bridge-bonded As 4 O formed by decomposition of excited terminally bound As 4 O. New bands in the 700-810-cm −1 region below As 4 O 6 that were favored on UV photolysis are assigned to bridge-bonded As 4 O x (x=2-5) species; As 4 O 6 was also formed on codeposition and increased by UV photolysis. As 4 is more reactive with O 3 than P 4 under the conditions of these experiments

Infrared spectra and ab initio calculations of disilane and methylsilane complexes with hydrogen fluoride in solid argon

Abstract: L'interaction la plus importante dans le complexe disilane… HF se trouve entre l'hydrogene acide et l'hydrogene du silyle. Formation d'une structure cyclique dans les complexes methyl-, dimethyl-, et trimethylsilanes dans laquelle le fluor interagit avec un hydrogene du methyle et l'hydrogene acide de HF interagit avec l'hydrogene du silyle

Oxidation of Phosphorus(III) Halides by Red Photolysis of Ozone Complexes in Solid Argon.

Abstract: PCl{sub 3}-O{sub 3} and PBr{sub 3}-O{sub 3} complexes in solid argon photolyze to give phosphoryl halides with red visible radiation that has no effect on isolated ozone. These observations and similar results for PH{sub 3}-O{sub 3} and P{sub 4}-O{sub 3} complexes show that the complex markedly increases the cross section for red photodissociation of ozone and suggest that this increase is due to the complex effectively lowering the barrier to dissociation by providing a strongly exothermic dissociation-recombination process.

Optical Spectra of Yb Atoms and Dimers in Rare Gas Matrices.

Abstract: Matrix isolated Yb vapor spectra show absorptions due to atoms, dimers, and higher aggregates. The atomic spectrum reveals strong 395 and 344 nm bands and very sharp weaker 267 and 255 nm absorptions in solid argon. The spectrum of Yb2 shows extensive vibrational stucture around 550 nm both in Ar and Kr matrices with a spacing of 48 cm−1. This absorption is assigned to a 6s2(1S0)6s2(1S0)(1Σ+g) →6s2(1S0)6s6p(1P1)(1Σ+u) transition similar to the one observed for group IIA metal dimers. Higher aggregate spectra overlap with the 550 nm dimer and weak atomic band.