William A. Guillory

Products of the Vacuum‐Ultraviolet Photolysis of Germane Isolated in an Argon Matrix

The vacuum‐ultraviolet photolysis of germane and the four deuterogermanes isolated in an argon matrix at temperatures between 4 and 25°K produces significant concentrations of several reactive species. Absorptions at 1839, 1813, 928, and 850 cm−1 have been assigned to a pyramidal GeH3 molecule and those at 1887, 1864, and 920 cm−1 have been assigned to a nonlinear GeH2 molecule. Digermane and the products of its photolysis are also produced and contribute considerably to the infrared spectra in the region below 1000 cm−1.

Study of H+NO2 in an Argon Matrix between 4 and 14°K; The Infrared Spectra of Matrix‐Isolated cis‐ and trans‐HONO

The matrix‐isolated infrared spectra of cis‐ and trans‐nitrous acid molecules have been obtained in argon at low temperatures by the reaction of H atoms with NO2. The spectra, which include 15N‐ and 18O‐substituted molecules, are not complicated by the stabilization of the acid in the presence of large concentrations of NO, NO2, and H2O. All six fundamentals of the cis and three of the trans isomers have been identified, and found generally to confirm the assignments of a previous study where some uncertainty did exist. The normal coordinate calculation performed for the cis molecule predicted the average frequencies of the four 15N‐ and 18O‐substituted species with an error of 0.60 cm−1 or 0.068%.

Vacuum‐Ultraviolet Photolysis of GeH3Cl; the Infrared Spectrum of Matrix‐Isolated GeH2Cl

The vacuum‐ultraviolet photolyses of GeH3Cl and GeD3Cl in argon and carbon monoxide matrices have been performed between 4 and 25°K. The major product of photolysis appears to be the free radical species GeH2Cl, and possibly some GeHCl as a result of secondary photolysis. Evidence that H atom detachment plays a major role in the photodissociation process is obtained by the formation of HCO in carbon monoxide matrix experiments. All six fundamental vibrational frequencies of GeH2Cl are observed and assignments are made for ν2 (GeH2valence bend), ν3(GeCl stretch), ν4(GeH2wag), and ν6(GeH2twist). Tentative assignments for the GeH stretching frequencies ν1(sym stretch) and ν5(antisym stretch) are made. A normal coordinate calculation using a six‐constant valence potential function suggests that the molecule is pyramidal with approximate sp3 hybridization. The structure, bonding, and thermodynamlc properties of GeH2Cl are also discussed and compared with other Group IV species.

Vacuum‐Ultraviolet Photolysis of GeCl4, HGeCl3, and H2GeCl2; The Matrix‐Isolated Infrared Spectra of GeCl3 and GeCl2

The vacuum‐ultraviolet photolysis of HGeCl3 and GeCl4 has resulted in evidence suggesting the stabilization of GeCl3 in argon, nitrogen, and carbon monoxide matrices at 4°K. Dichlorogermane photolysis has led to the stabilization and isolation of GeCl2. Additional evidence has been obtained for H‐atom photodetachment resulting in the isolation of a GeCl3 species having two stretching frequencies, and therefore is pyramidal in shape. A normal coordinate calculation using a four‐constant valence potential function suggests that the angle between the threefold symmetry axis and any of the GeCl bonds is approximately 73° (Cl–Ge–Cl angle, 111°), slightly greater than the sp3 hybridization angle.

Ultraviolet Photolysis of GeH3Br; Infrared Spectra of Matrix‐Isolated GeH2Br and GeHBr

The ultraviolet photolyses of GeH3Br and GeD3Br in an argon matrix have been performed between 8 and 24°K. The major products resulting from photolysis appear to be GeH2Br and GeHBr and their deuterated counterparts. All the fundamental vibrational frequencies of these species are observed with the exceptions of one of the GeH stretches and the GeH2 and GeD2 valence bends (ν2) of GeH2Br and GeD2Br, respectively. The results of the normal coordinate and self‐consistent extended Huckel calculations are consistent with the experimental observations and suggest that GeH2Br and GeHBr are pyramidal and bent, respectively. Structural and bonding properties of these species are also discussed.

Matrix-isolation study of the vacuum-ultraviolet photolysis of NF3: The electronic spectrum of the NF2 free radical

Abstract The vacuum-ultraviolet photolysis of NF 3 in an argon or a carbon monoxide matrix at 14°K leads to the production of NF 2 , identified by its infrared absorption. F-atom photodetachment also leads to the appearance of FCO in the carbon monoxide matrix studies. The photodissociation of NF 2 by 2537 A radiation has been confirmed. The appearance of a band system near 2600 A with position and band spacings close to those previously reported for NF 2 in the gas phase demonstrates that the lower state of the gas-phase transition is the ground state of the molecule and confirms the assignment of the observed structure to a progression in the upper-state bending vibration.

The bonding, structure, and photochemistry of some stable and unstable germanium species

Abstract The ultraviolet and vacuum-ultraviolet photolyses of GeH 4 , GeH 3 Cl, GeH 2 Cl 2 , GeHCl 3 , GeCl 4 , GeH 3 Br, and GeH 2 Br 2 in argon and carbon monoxide matrices have been performed between 4° and 24° K. The results of these experiments support the successful isolation and characterization of a variety of germanium free-radical species produced as a result of primary and secondary photolytic processes. In order to control, characterize and understand the various elementary processes (photochemical and fragment diffusion) occurring in the matrix, both in situ photolysis as well as simultaneous deposition and photolysis were performed as a function of photolyzing radiation, temperature (of the cold window), and concentration (M/ R = matrix/reactive material). The identification and structure of the photochemically produced free radicals were obtained from the vibrational (infrared) spectrum before and after photolysis. In some cases, complete vibrational assignments were possible. Force field (normal coordinate) calculations were also performed in order to corroborate these assignments, within the limitation of their application to matrix isolated spectra. Finally, the structural and bonding properties of these free radicals, as reflected by their vibrational frequencies, are compared with similar stable and unstable Group IVA species in an effort to understand the major effect(s) controlling their geometry. The geometries obtained on the basis of the experimental observations are compared with those predicted by Walshs semiempirical MO treatment and Self-Consistent Extended Huckel calculations. In addition, a simple thermodynamic argument in conjunction with elementary quantum mechanics is used as a tool for predicting the structure of some of these simple free-radical species.