The recombination reaction H + O2 (+M) → HO2 was studied by laser flash photolysis in a high pressure flow cell, over the temperature range 300–900 K, 1.5–950 bar and bath gases M = He N2. Earlier experiments Hahn et al. (Phys. Chem. Phys. 2004, 6, 1997) gas Ar were also extended. data analyzed terms of unimolecular rate theory employing new calculations relevant molecular parameters. Improved energy transfer parameters for He, Ar, N2, H2O could thus be obtained complete falloff curves...

Abstract Expressions for representing the pressure dependence of unimolecular dissociation and reverse recombination reactions are compared. Situations considered where broadening corresponding falloff curves is particularly pronounced, i.e. factors at center curves, F cent , very small correspondingly become “broad”. Such situations arise when molecules with large numbers low-frequency modes high-temperature considered. Recombination polyatomic species in atmospheric chemistry combustion...

The potential energy surface of the HO+O⇔HO2⇔H+O2 reaction system is characterized by ab initio calculations. complex-forming bimolecular then treated statistical rate theory, using adiabatic channel and classical trajectory calculations for HO+O⇔HO2 HO2⇔H+O2 association/dissociation processes. Specific constants k(E,J) both reactions as well thermal are calculated over wide ranges conditions. Open shell quantum effects important up to room temperature. good agreement with experimental...

Master equations for thermal unimolecular reactions and the reverse recombination are solved a series of model reaction systems evaluated with respect to broadening factors. It is shown that weak collision center factors $F_{cent}^{wc}$Fcentwc can approximately be related efficiencies βc through relation ≈ max {βc0.14, 0.64(±0.03)}. In addition, it investigated what extent falloff curves in general expressed by limiting low high pressure rate coefficients together central Fcent only. there...

The dissociation/recombination reaction CH4 (+M) ⇔ CH3 + H is modeled by statistical unimolecular rate theory completely based on dynamical information using ab initio potentials. results are compared with experimental data. Minor discrepancies removed fine-tuning theoretical energy transfer treatment accounts for transitional mode dynamics, adequate centrifugal barriers, anharmonicity of vibrational densities states, weak collision and other effects, thus being “complete” from a point view....

The temperature dependences of the rate constants and product branching ratios for reactions FeO(+) with CH4 CD4 have been measured from 123 to 700 K. 300 K are 9.5 × 10(-11) 5.1 cm(3) s(-1) reactions, respectively. At low temperatures, Fe(+) + CH3OH/CD3OD channel dominates, while at higher FeOH(+)/FeOD(+) CH3/CD3 becomes majority channel. data were found connect well previous experiments translational energies. kinetics simulated using a statistical adiabatic model (vibrations during...

A comparably simple new analytical expression of the potential energy surface for HO+O⇔HO2⇔H+O2 reaction system is designed on basis previous high precision ab initio calculations along minimum path HO2→H+O2 and HO2→HO+O dissociations. Thermal rate constants HO+O→H+O2 are determined by extensive classical trajectory calculations. The results depend policy to solve zeropoint problem. We show that, with chosen policy, there nearly equal amounts statistical nonstatistical backdissociations...

The potential energy surface of the reaction H+O2→HO2 is characterized by ab initio calculations. Based on these results, classical trajectory calculations capture T, D, H, and muonium O2 are made. Thermal rate constants as well energy- angular momentum-specific determined. calculated high pressure recombination at 300 K agree with limited experimental information available so far which gives confidence in computed temperature dependence (calculations over range 30 to 5000 K). coefficients...

The addition of atoms to linear molecules forming or nonlinear adducts is treated using standardized valence potentials. dynamics analyzed with a combination classical trajectory (CT) and statistical adiabatic channel (SACM) calculations. For conditions, the two approaches coincide. transition from nonadiabatic investigated CT low-temperature quantum range studied by SACM. Thermal capture rate constants are represented in analytical form. rigidity factors expressed terms molecular parameters...

The reactions of FeO+ with H2, D2, and HD were studied in detail from 170 to 670 K by employing a variable temperature selected ion flow tube apparatus. High level electronic structure calculations performed compared previous theoretical treatments. Statistical modeling the isotope dependent rate constants was found reproduce all data, suggesting reaction could be well explained efficient crossing sextet quartet surface, rigid near thermoneutral barrier accounting for both inefficiency...

Classical trajectory calculations of ion–permanent quadrupole+induced dipole capture processes are performed over wide ranges conditions. The results expressed in two-parametric analytical form, and analyzed with respect to the transition from sudden adiabatic dynamics. compared statistical channel model (SACM). For this purpose, potential curves approximate form. agreement between classical SACM is excellent range quasiclassical motion collision partners. Analytical expressions can well...

The reactions of FeO⁺ with H₂ and Fe⁺ N₂O were studied respect to the production reactivity electronically excited ⁴Fe⁺ cations.

Classical trajectory calculations of ion–permanent+induced dipole capture processes are performed over very wide ranges conditions. The results represented in a simple, two-parametric analytical form high precision. transition from adiabatic to nonadiabatic dynamics is expressed terms the Massey parameter. In range, perfect agreement (better than 0.4%) derived thermal rate constants classical trajectories and accurate statistical channel (SACM) obtained.

Classical trajectory (CT) calculations of dipole–dipole capture processes are performed over wide ranges conditions. Besides the anisotropic potential, an isotropic dispersion potential is accounted for. The Massey parameter system characterizes transition between adiabatic and nonadiabatic (sudden) dynamics. In limit, under classical conditions, CT statistical channel model (SACM) give identical thermal rate constants which can be expressed in simple parametrized form. from quantum to SACM...

Statistical adiabatic channel model/classical trajectory (SACM/CT) calculations have been performed for transitional mode dynamics in the simple bond fission reactions of C6H6+ → C6H5+ + H and n-C6H5C4H9+ C7H7+ n-C3H7. Reduced-dimensionality model potentials designed that take advantage ab initio results as far available. Average anisotropy amplitudes were fitted by comparison calculated specific rate constants k(E,J) with measured values. The kinetic shifts k(E) curves corresponding...

The combination of two linear rotors forming or nonlinear adducts is treated using standardized valence potentials. Classical trajectory (CT) and statistical adiabatic channel (SACM) calculations are used for the calculation thermal capture rate constants. At very low temperatures, only SACM applies. intermediate temperatures CT approach each other; however, Landau–Zener-type multiple crossings potentials introduce local nonadiabaticity which has to be accounted for. high-temperature...

The rates of the reactions Fe⁺ + N₂O → FeO⁺ N₂ and CO CO₂ are modeled by statistical rate theory accounting for energy- angular momentum-specific constants formation primary secondary cationic adducts their backward forward reactions.

Electronically nonadiabatic transitions in a collinear H2 + H+ system have been studied both quantum mechanically and with classical mechanics using diatomics-in-molecules type potential energy surface fitted to recent ab initio data. The dynamical calculations are carried out by employing standard close-coupling method hyperspherical coordinates the quasiclassical trajectory were basic hopping method. Special emphasis is placed on qualitative analysis of physical mechanisms electronically...

Transitional modes in simple unimolecular bond fission and the reverse recombination reactions are characterized quantitatively by statistical adiabatic channel (SACM) classical trajectory (CT) calculations. Energy E- angular momentum J-specific numbers of open channels (or activated complex states) W(E,J) capture probabilities w(E,J) determined for a series potentials such as ion—dipole, dipole–dipole, various model valence potentials. SACM CT treatments shown to coincide under conditions....