Fine structure branching ratios and translational energies of O(3P j) atoms produced from collision induced intersystem crossing of O(1D) atoms

Abstract

Collision induced intersystem crossing of O(2p 1D) to O(2p 3Pj) j=0,1,2 was studied by vacuum-ultraviolet laser induced fluorescence. The nascent j-branching ratios of O(3Pj) produced from collision of O(1D) with Xe, Kr, N2, CO2, and CF3H at the collision energy of 15.6, 14.7, 11.4, 13.0, and 14.4 kcal/mol are [O(3P0)]/[O(3P1)]/[O(3P2)]=(0.28±0.04)/(0.58±0.05)/1, (0.33±0.05)/(0.45±0.07)/1, (0.23±0.05)/(0.35±0.05)/1, (0.14±0.05)/(0.41±0.05)/1, and (0.20±0.05)/(0.45±0.05)/1, respectively. The j-branching ratios are discussed in terms of potential curve crossing between singlet and triplet surfaces and nonadiabatic nature of the potential surfaces. Doppler profiles of the product O(3Pj) atoms were measured as a function of time delay between pump and probe laser pulses. By calculating the kinetic energy from the Doppler profiles, electronic energy transfer efficiencies to the internal energy of N2, CO, CO2, and CF3H are obtained to be (30±7), (31±7), (49±3), and (52±5)%, respectively.

Vibrational relaxation of CO2(ν2) by O(3P) in the 142–490 K temperature range

“…Under typical experimental conditions, all of the nascent O( 1 D) is converted to O( 3 P) in less than a microsecond – much faster than the vibrational energy transfer of interest. The O( 3 P J ) spin sublevels will exhibit a nearly statistical distribution following the quenching of O( 1 D) by the abundance of Xe [ Matsumi et al , 1994]. In the upper atmosphere, the sublevels are also likely thermalized at the local kinetic temperature due to the long O‐atom chemical lifetime.…”

Dynamics of the O(1D)+CO2 oxygen isotope exchange reaction

“…This value is consistent with a previous flow tube study which used a higher collision energy of 13.0 kcal/mol; by measuring the product O( 3 P 2 ) Doppler profile at 130.2 nm, it was found that 49Ϯ3% of the available energy was deposited into the product CO 2 . 23 The slow peak, with ͗E t ͘ϭ3.1 kcal/mol, was also fit with a broad P͑E͒. The maximum translational energy of this channel is 7.7 kcal/mol, equal to the collision energy.…”

Reaction Dynamics of O(1D,3P) + OCS Studied with Time-Resolved Fourier Transform Infrared Spectroscopy and Quantum Chemical Calculations

“…44 In reaction 13b, the distribution of spin-orbit states of the product S atom is expected to be statistical because the mechanism is likely similar to the reaction O( 1 D) + CO 2 in which the distribution in respective J states of O( 3 P J ) was reported to be nearly statistical. 45 If Similar to the procedures described for the reaction O ( 3 P) + OCS in Section A, the best fit spectrum was obtained with E* ) 30 000 ( 500 cm -1 , as shown in Figure 6. Trace a is a stick diagram of ∆V 3 ) -1 transitions calculated with the ν 1 /ν 2 polyad approximation, 14 and trace b represents the same distribution convoluted with fwhm ) 4 cm -1 ; the latter provides a practical comparison of vibrational distributions with experimental data.…”