Hong-Ming Yin

Quantum dynamics study of the Cl+D2 reaction: Time-dependent wave packet calculations

The quantum dynamics of the Cl+D2 reaction has been studied by means of time-dependent quantum wave packet calculations on the G3 and BW2 potential energy surfaces. Initial state-specific total reaction probabilities and integral cross sections are calculated, and the thermal rate constant is obtained. On the G3 surface, the effect of the reagent’s rotational excitation on the reactivity is negative, while on the BW2 surface, the rotation of reagent has positive effect on the reactivity. Comparison of the thermal rate constants on the G3 and BW2 surfaces with experimental measurement is shown.

Photodissociation dynamics of the S2 state of CH3ONO: State distributions and alignment effects of the NO (X2Π) photofragment

The photodissociation dynamics of methyl nitrite (CH3ONO) was studied using 266 nm laser photolysis, and NO photofragments X 2∏ ν″=0,1,2,3) were probed by single photon laser-induced fluorescence spectroscopy. The ground vibrational state of the NO was found to be most populated, and the rotational distributions of each vibrational level were quite hot. The alignment A0(2) between the electronic transition dipole moment involved in the absorption of the parent molecule and the rotational angular momentum J of the photofragment NO (v″=0) was measured. Polarization experiments showed that the rotational angular momentum of NO was aligned perpendicularly to the transition moment of the parent molecule. The negative A0(2) values and a preferential population of the ∏− doublet state revealed that the dissociation process has some characteristics of in-plane dissociation.

Photodissociation of nitrobenzene at 266 nm: Experimental and theoretical approach

The 266 nm photodissociation of gaseous nitrobenzene has been studied by monitoring the NO X 2Π product using the single-photon laser-induced fluorescence technique. The rotational population and internal energy distributions of fragment NO product were determined. In the experiment, we only observed the rotational state distributions of the NO fragment for v″=0. The rotational state distributions of the nascent NO photofragment can be characterized by a Boltzmann temperature of 3300±300 K. Ab initio calculations were performed to characterize the transition state and to determine the barrier height for the rearrangement of nitrobenzene to phenylnitrite. A clear photodissociation picture has been proposed theoretically.

Photolysis of o-nitrobenzaldehyde in the gas phase: a new OH* formation channel.

Photolysis of gaseous o-nitrobenzaldehyde (o-NBA) with selected different excitation wavelengths (355-400 nm) is investigated, and the nascent OH radical is detected by the single-photon laser-induced fluorescence (LIF) technique. The relative quantum yield and rotational excitation of OH formation are found to be dependent on the excitation energy. The distributions of rotational, spin-orbit, and Lambda-doublet states are obtained at 355-400 nm by analyzing the experimental data. The OH radicals are found to be vibrationally cold at all photolysis wavelengths. The spin-orbit and Lambda-doublet states have nonstatistical distributions. To understand the dissociative process involved in the OH-generating channel, DFT calculations are performed. Based on both experimental and theoretical results, possible photolysis channels of o-NBA leading to the OH fragment are proposed and discussed.

Photodissociation Dynamics of Nitromethane and Nitroethane at 266 nm

Measurements of the nascent OH product from photodissociation of gaseous nitromethane and nitroethane at 266 nm were performed using the single-photon laser induced fluorescence technique. The OH fragment is found to be vibrationally cold for both systems. The rotational state distribution of nitromethane are Boltzmann, with rotational temperature of T-rot=2045 +/- 150 and 1923 +/- 150 K for both (2)Pi(3/2) and (2)Pi(1/2) states, respectively. For nitroethane, the rotational state distribution shows none Boltzmann and cannot be well characterized by a rotational temperature, which indicates the different mechanisms in producing OH radicals from photodissociation of nitromethane and nitroethane. The rotational energy is calculated as 14.36 +/- 0.8 and 4.98 +/- 0.8 kJ/mol for nitromethane and nitroethane, respectively. A preferential population of the low spin-orbit component ((2)Pi(3/2)) is observed for both nitromethane and nitroethane. The dominant population of Pi(+) state in two Lambda-doublet states is also observed for both nitromethane and nitroethane, which indicates that the unpaired pi lobe of the OH fragment is parallel to the plane of rotation.

A density function theory study on the properties and decomposition of CF3OF

The density function theory was used to calculate the potential energy surface for the decomposition of CF3OF. The geometries, vibrational frequencies and energies of all stationary points were obtained. The calculated harmonic frequencies agreed well with the experimental ones. Three decomposition channels of CF3OF were studied. The calculated reaction enthalpy (29.85 kcal/mol) of the elimination reaction CF3OF --> CF2O + F-2 was in good agreement with the experimental value (27.7 kcal/mol). The O-F bond of CF3OF is broken easily by comparing the energies, while the decomposition channel to yield the CF30 and F radicals is the main reaction path

Theoretical study of the reaction H+NF3 -> NF2+HF

The direct transition state theory method is used to study the reaction of H with NF3 to form NF2 and HF. Potential energy information, including equilibrium geometries, first and second energy derivatives and energies, is obtained from the ab initio calculations. To determine the calculated level and basis set of the energies, we calculate the bond dissociation energy at the MP2/6-31G(d), QCISD/6-311G(d,p) and G2(MP2) levels. Some suitable points on the minimum energy path are chosen for calculation of the properties of the reaction path and rate constants. The rate constants and kinetic isotope effect are calculated in the temperature range 300–2500 K by using variational transition state theory plus multidimensional semiclassical tunneling transmission coefficients.

Detection of OH Radical in the Photodissociation of p-Aminobenzoic Acid at 266 nm

Photodissociation of p-aminobenzoic acid at 266 nm was investigated by probing the nascent OH photoproduct employing the laser-induced fluorescence technique. It was found that the nascent OH radical was vibrationally cold and its rotational state distribution conformed to be a Boltzmann behavior, characterized by a rotational temperature of 1040 110 K. The rotational energy of OH was determined to be 8.78 0.84 kJ/mol. Between the two spin-orbit states of OH, 23/2 and 21/2, the former was found to be preferentially populated. The distribution of the (A) state for the -doublet was dominant. Finally, a probable mechanism for the formation of OH produced from the photodissociation of p-aminobenzoic acid is discussed.

Dynamical Lie algebraic treatment for the A+BC scattering

We report the study of translational-vibrational energy transfer in the a + bc scattering using the dynamical lie algebraic approach combined with the intermediate picture. the rotational sudden approximation is applied to treat the rotational motion of the bc molecule, which is regarded as an anharmonic oscillator. the calculated results show that the transition probabilities increase with increasing rotational quantum number. comparison with those obtained in the collinear collision of system a + bc manifests that the transition probabilities here increase indeed. (c) 2001 john wiley sons, inc.