An experimental and theoretical study of the high temperature reactions of the four butyl radical isomers.

The high temperature gas phase chemistry of the four butyl radical isomers (n-butyl, sec-butyl, iso-butyl, and tert-butyl) was investigated in a combined experimental and theoretical study. Organic nitrites were used as convenient and clean sources of each of the butyl radical isomers. Rate coefficients for dissociation of each nitrite were obtained experimentally and are at, or close to, the high pressure limit.

An Experimental and Theoretical Study of the Thermal Decomposition of CH Isomers.

The chemistry of small unsaturated hydrocarbons, such as 1,3-butadiene (1,3-CH), 1,2-butadiene (1,2-CH), 2-butyne (2-CH), and 1-butyne (1-CH), is of central importance to the modeling of combustion systems. These species are important intermediates in combustion processes, and yet their high-temperature chemistry remains poorly understood, with various dissociation and isomerization pathways proposed in the literature. Here we investigate the thermal decompositions of 1,3-CH, 1,2-CH, 2-CH, and 1-CH inside a diaphragmless shock tube, at postshock total pressures of 26-261 Torr and temperatures ranging from 1428 to 2354 K, using laser schlieren densitometry.

Thermal Dissociation and Roaming Isomerization of Nitromethane: Experiment and Theory.

The thermal decomposition of nitromethane provides a classic example of the competition between roaming mediated isomerization and simple bond fission. A recent theoretical analysis suggests that as the pressure is increased from 2 to 200 Torr the product distribution undergoes a sharp transition from roaming dominated to bond-fission dominated. Laser schlieren densitometry is used to explore the variation in the effect of roaming on the density gradients for CH3NO2 decomposition in a shock tube for pressures of 30, 60, and 120 Torr at temperatures ranging from 1200 to 1860 K.

Isotope effects and spectroscopic assignments in the non-dissociative photoionization spectrum of Nâ‚‚.

Photoionization efficiency spectra of (14)N2, (15)N(14)N, and (15)N2 from 15.5 to 18.9 eV were measured using synchrotron radiation at the Advanced Light Source at Lawrence Berkeley National Laboratory with a resolution of 6 meV, and significant changes in peak energies and intensities upon isotopic substitution were observed.