James S. Shirk

The infrared laser photoisomerization of HONO in solid N2 and Ar

The IR induced photoisomerization of HONO in solid N2 and Ar is a single photon process. The isomerization is not first order but follows a rate law (d [HONO]/dt) = (kc/π r2l)[I0−I][HONO]. Extensive energy migration occurs in these solids. The reaction occurs at sites where the isomerization is least hindered by the cage. There is evidence for the importance of direct coupling of the excited mode and the reaction coordinate.

Isomerization of hono in solid nitrogen by selective vibrational excitation

Abstract The cis—trans photoisomerization rates of HONO in solid nitrogen after single-photon excitation into two different vibrational modes of each isomer were measured. The rates are inconsistent with RRKM predictions and raise the possibility of mode-selective reactions in matrices. The barrier to HONO isomerization is estimated to be 3250 ± 100 cm −1 above the zero-point energy of trans-HONO.

Infrared Spectrum of AlCl3 and Al2Cl6 Isolated in Solid Argon

The infrared spectra of monomeric and dimeric aluminum chloride trapped in solid argon have been observed. For the monomer AlCl3 four infrared‐active fundamentals including the symmetric stretch are observed, implying a pyramidal equilibrium structure. Other experimental data for AlCl3 are consistent with such a structure. A normal coordinate analysis suggests a Cl–Al–Cl angle near 112°. The structures of the aluminum halides are compared with observed trends in alkaline‐earth dihalides.

Infrared laser photoisomerization of 2-fluoroethanol in argon

Abstract Different products result from single-photon IR photolysis of 2-fluoroethanol in solid argon depending upon the vibrational mode that is excited. Irradiation of the OH stretch causes an interconversion of the two most stable isomers T 1 and G g . Irradiation of one CH stretch results in the formation of significant yields of the less stable G 1 and T g isomers. The isomers of 2-fluoroethanol can be photooriented in argon by IR irradiation.

Infrared spectra of monomeric gallium trihalides in solid argon

We have observed the infrared spectra of GaCl3, GaBr3, and GaI3 in solid argon. Some absorptions due to the dimers are also reported. Isotopic shifts were partially resolved in several cases. The observed spectra are all consistent with a planar D3h structure for each of these molecules.

Infrared spectra of AlF3 in solid argon

Abstract Three infrared absorptions are assigned to AlF3 isolated in solid argon: ν2 = 286.2 cm−1, ν3 = 909.4 cm−1, and ν4 = 276.9 cm−1. The multiplet pattern previously reported near 950 cm−1 is not present in carefully isolated AlF3. Our spectra do not conclusively rule out a pyramidal structure for AlF3; however, no infrared absorptions can be confidently assigned to ν1, the symmetric stretch.

Double beam intracavity laser spectrometers I. Flash lamp pumped

Abstract We describe a double beam intracavity dye laser spectrometer which is capable of a direct quantitative measurement of the absorbance of weak absorbers. The instrument is sensitive to broad band absorptions. The spectrometer can be modeled to allow a prediction of its sensitivity. Experimentally, the spectrometer reported here is about as sensitive as earlier flash lamp pumped intracavity spectrometers.

Infrared spectra of AlCl2Br, AlClBr2, and AlBr3 in solid argon

We report the ir spectra of AlCl2Br, AlClBr2, and AlBr3. It is pointed out that the vibrational spectra of AlCl2Br and AlClBr2 can provide a novel and sensitive test for small deviations from planarity of AlCl3. The observed spectra imply a planar D3h structure for each of these trihalides.

Oxygen atom reactions with SiHCl3 in solid argon: The infrared spectrum of SiCl3OH

Abstract SiCl 3 OH is identified as a major reaction product of uv photolysis of SiHCl 3 O 3 and vacuum uv photolysis of SiHCl 3 O 2 mixtures in solid argon. The ir spectrum of normal and isotopically substituted SiCl 3 OH molecules is reported. The frequencies were fitted to a general valence force field.

The infrared spectrum of InCl3 in solid argon

Abstract We report the infrared spectrum of InCl 3 in solid argon. The observed spectrum is consistent with a planar D 3 h structure for this molecule.