The potential energy surfaces for the butoxy radical dissociation into R·＋O on the six low-lying electronic states have been determined with the combined CASSCF and MR-CI methods. The isomerization reactions between the different conformers of 1- and 2-butoxy radicals at the X and B states have been also investigated with the MP2, B3LYP, and CASSCF methods. The non-radiative decay mechanisms of butoxy radicals at the B state have been characterized with the computed potential energy surfaces and intersections. Supported by recent LIF experimental results, it was predicted that the t-butoxy radical would predissociate via the B/C intersection. As to 1- and 2-butoxy radicals, the relative energies of the transition states for the isomerization reactions between conformers at the B state are much lower than those of the B/C intersections, resulting in the predominance of the isomerization in the decay of the B state for 1- and 2-butoxy radicals.
The effects of the pressure and discharge voltage on the spectral intensities of the second positive and first negative systems were studied in a pulsed nitrogen discharge supersonic flee-jet. The results show that a stabilized discharge condition was reached when the vacuum chamber pressure increased to 100 Pa. Both N2（C^3∏u） and N＋（B^2∑u^＋） states were highly populated at a pressure of 100 Pa to 130 Pa. The active state N2（C^3∏u）could be selectively populated at a low pressure of 10 Pa and a discharge voltage of 4500 V. Different populating mechanisms under the experimental conditions for N2（C^3∏u） and N＋（B^2∑u^＋） states were proposed to account for the experimental results.
