Alan Snelson

Infrared Spectrum of LiF, Li2F2, and Li3F3 by Matrix Isolation

The infrared spectrum of the vapor species above lithium fluoride has been examined in the frequency range 4000–200 cm−1 using the matrix isolation technique. The spectrum is interpreted in terms of monomer, dimer, and trimer molecules. Isotope shifts are consistent with a planar cyclic configuration for the dimer. The 7Li dimer has the following infrared‐active fundamentals: v(B3u)=655 cm−1, v(B2u)=570 cm−1, and v(B1u)=300 cm−1. The remaining infrared‐inactive frequencies of the dimer are estimated at v(Ag)=560 cm−1, v(Ag′)=280 cm−1, and v(B1g)=490 cm−1. The following frequencies are tentatively assigned to the infrared active fundamentals of the 7Li trimer, 230, 267, 509, and 736 cm−1.

Gas phase generation of O2(+Δg) at atmospheric pressure by direct laser excitation☆

Abstract O 2 ( 1 Δ g ) was generated in the gas phase at atmospheric pressure by direct laser excitation. A Holobeam model 255 Nd—YAG laser with an output at 1065 nm was used to achieve the transition O 2 ( 3 Σ g − , v = 0) → O 2 ( 1 Δ g , v = 1) The mean lifetime τ of the resulting excited oxygen species in the gas phase at atmospheric pressure was measured to be 0.124 ± 0.012 s. This corresponds to a bimolecular rate constant k 2 for the overall reaction O 2 ( 1 Δ g , v = 1) + O 2 ( 3 Σ g − ) → 2O 2 ( 3 Σ g − ) of (3.3 ± 0.4) × 10 −19 molecule −1 cm 3 s −1 , a factor of 10 below the currently accepted value for ground state oxygen deactivation of singlet oxygen. Possible reasons for this difference are discussed.

IR matrix isolation spectra of some perfluoro organic-free radicals Part 1. C2F5

Abstract The pentafluoro ethyl radical has been prepared by the pyrolysis of C 2 F 5 I in a platinum effusion tube at ⋍650°C and isolated in an argon matrix. By elimination of absorption bands attributable to known fluorine compounds and from relative intensity measurements on the remaining bands, twenty frequencies were assigned C 2 F 5 in the spectral range 4000–200 cm −1 . Fourteen of these frequencies were assigned as fundamentals of C 2 F 5 , with C s symmetry, and the remainder to combination or overtone modes of the radical.

Pressure dependence of the CO + OH rate constant in O2 + N2 mixtures

Abstract The rates of production of CO 2 in the reactions, CO + OH and CO + OH + iso-C 4 H 10 , have been used to determine the pressure dependence of the CO + OH rate constant at 31.5°C. Total reaction pressures of 100–600 torr were used with O 2 + N 2 mixtures for the “make up gas”. Photolysis of H 2 O 2 provided the hydroxyl radical source. CO 2 production was measured by gas chromatography. A high pressure ( P ⩾ 300 torr) value for k (OH + CO) = (2.69 ± 0.40) × 10 −13 cm 3 molecule −1 s −1 was determined. The change from the low to the high pressure rate constant occurs in the region 100 torr P k (OH + iso-C 4 H 10 ) = (1.59 ± 0.18) × 10 −12 cm 3 molecule −1 s −1 was obtained at 100 torr relative to the low pressure value of k (OH + CO) = 1.50 × 10 −13 cm 3 molecule −1 s −1 .

The infrared matrix isolation spectra and normal coordinate analysis of LiBeF3 and the related species Li2BeF4 and (LiBeF3)2

Abstract Beryllium fluoride vapor was reacted with 6 Lif: and 7 LiF at 900–1000 °C in an effusion tube. The infrared spectrum of the effusate was obtained in a neon matrix, in the range 4000-190 cm −1 . One mixed halide, LiBeF 3 was identified and the existence of (LiBeF 3 ) 2 or Li 2 BeF 4 inferred. For LiBeF 3 seven of the possible nine infrared frequencies were observed. A normal coordinate analysis for LiBeF 3 is presented and used to assign the experimental frequencies. Calculated mean amplitudes of vibration and calculated frequencies from normal coordinate analyses of Li 2 BeF 4 and (LiBeF 3 ) 2 are reported.

Gas phase observation of the 1.27-μ emission of singlet delta oxygen generated at atmospheric pressure by heterogeneous photosensitization

Singlet oxygen was generated in the gas phase using heterogeneous photosensitization and atmospheric pressure. The emission of O2 (1Δ → 3Σg) at 1.27-μ has been observed.

Gas phase generation of singlet oxygen at atmospheric pressure

Abstract Evidence is presented for the gas phase generation of singlet oxygen using heterogeneous photosensitization and atmospheric pressure.

Solubility of ozone in some flourocarbon solvents

Abstract The solubilities of ozone 0-6 Wt% in air or oxygen, in 14 Fluorocarbon solvents have been determined at ambient temperature. Solubilities ranged from 50 to 700 ppm (wt) for a gas phase 0 3 concentration of 6 Wt%. Compounds with 0 3 solubilities 3 solubilities >200 ppm (wt) showed apprarent marked Henrys Law deviations.

Kinetics of the Homogeneous Gas Phase Hydrolysis of CCl3COCl, CCl2HCOCl, CH2CICOCl and COCl2

The homogeneous gas phase hydrolysis kinetics of the above compounds has been investigated in the 470° to 620°K temperature range. The following biomolecular rate constants were obtained: k(CCl3COCl) = 2.54 × 106 exp (−18,350 ± 1750)/RT, k(CClH2COCl) = 1.14 × 108 exp (−22,630 ± 780)/RT, and fr(COCl2) = 9192 exp (−14,200 ± 2100)/RT liter mole−1 sec−1. Experimental difficulties prevented data being obtained for CHCl2COCl. The half lives of these species with respect to homogeneous gas phase hydrolysis in the atmosphere have been estimated and it is concluded that this is not an efficient conversion process. Heterogeneous hydrolysis by water droplets may be a more efficient atmospheric scavenging process for these compounds.

Electron paramagnetic resonance and X-ray studies in doped silver carbonate.

For Y(III)‐ or Gd(III)‐doped silver carbonate with the ratio of dopant to Ag, nu2009≥u20090.005, a new orthorhombic crystal structure is reported with au2009=u200913.94 A, bu2009=u20095.97 A, and cu2009=u20095.30 A, determined from x‐ray studies. Electron paramagnetic resonance investigations on γ‐irradiated Y(III)‐doped silver carbonate also indicate the presence of a new crystal structure. The same new crystal structure is thermally attained in undoped carbonate at ∼150°C under 3 atm of CO2.