Showing papers by "Bruce S. Ault published in 2010"

Characterization of iso-CF2I2 in frequency and ultrafast time domains

Abstract: The photolysis of diiododifluoromethane (CF2I2) in condensed phases was studied by a combination of matrix isolation and ultrafast time-resolved spectroscopy, in concert with ab initio calculations. Photolysis at wavelengths of 355 or 266 nm of CF2I2:Ar samples (1:5000) held at ∼8 K yielded iso-CF2I2 (F2C–I–I), a metastable isomer of CF2I2, characterized here for the first time. The infrared (IR) spectra of this isomer were recorded in matrix experiments, and the derived positions of the C–F stretching modes are in very good agreement with the predictions of high level ab initio calculations, which show that the iso-form is a minimum on the CF2I2 ground state potential energy surface. The formation of this isomer following 350 nm excitation of CF2I2 in room temperature CCl4 solutions was monitored through its intense C–F stretching mode by means of ultrafast time-resolved IR absorption. Together, matrix isolation and ultrafast IR absorption experiments suggest that the formation of iso-CF2I2 occurs via re...

Infrared matrix isolation and theoretical study of the initial intermediates in the reaction of ozone with cis-2-butene.

Abstract: Matrix isolation studies combined with infrared spectroscopy of the twin jet codeposition of ozone and cis-2-butene into argon matrices have led to the first observation of several early intermedia...

Investigation of the thermal and photochemical reactions of ozone with 2,3-dimethyl-2-butene.

Abstract: The matrix isolation technique, combined with infrared spectroscopy and twin jet codeposition, has been used to characterize intermediates formed during the ozonolysis of 2,3-dimethyl-2-butene (DMB). Absorptions of early intermediates in the twin jet experiments grew up to 200% upon annealing to 35 K. A number of these absorptions have been assigned to the elusive Criegee intermediate (CI) and secondary ozonide (SOZ) of DMB, transient species not previously observed for this system. Also observed was the primary ozonide (POZ), in agreement with earlier studies. The wavelength dependence of the photodestruction of these product bands was explored with irradiation from λ ≥ 220 to ≥580 nm. Merged jet (flow reactor) experiments generated “late” stable oxidation products of DMB. A recently developed concentric jet method was also utilized to increase yields and monitor the concentration of intermediates and products formed at different times by varying the length of mixing distance (d = 0 to −11 cm) before rea...