Recent progress in state-resolved kinetic models of thermal relaxation and dissociation of oxygen based on highfidelity transition rate coefficients is presented. Specifically, three types of collisions encountered in high-temperature flows are discussed: O2–O, O2–N, and O2–N2. For these molecular systems, the thermal relaxation times and dissociation rate coefficients, obtained from extensive ...

In this paper we report slice imaging polarization experiments on the state-to-state photodissociation at 42 594 cm 1 of spatially oriented OCS(v2 = 1|JlM = 111) CO(J) + S(D2). Slice images were measured of the three-dimensional recoil distribution of the S(D2) photofragment for different polarization geometries of the photolysis and probe laser. The high resolution slice images show well separ...

ion in the NH3+ IH20 system. 34 The D2 molecule can interact directly with the electron density on the nitrogen in this configuration. Other configurations such as the above but with the D2 rotated by 90· or an in-plane approach appear less favorable. Ab initio and semiempirical calculations of portions of the NH/ potential energy surface indicate that the above configuration represents a minim...

The reaction path is an important concept of theoretical chemistry. We employ the definitions of the intrinsic reaction coordinate (IRC), the gradient extremal (GE), and the Newton trajectory (NT). The usual imagination in chemistry is that a minimum energy path is in a convex region of the potential energy surface. We describe different schemes of convexity to handle the situation. It comes ou...

Femtosecond ~fs! dynamics of reactions of cyclic ethers, symmetric and asymmetric structures, are reported. The diradical intermediates and their b-cleavages, which involve simultaneous C-C, C-H s-bond breakage and C-O, C-C p-bond formation, are observed and studied by fs-resolved mass spectrometry. To compare with experiments, we present density functional theory calculations of the potential ...

The task of finding saddle points on potential energy surfaces plays a crucial role in understanding the dynamics of a micromolecule as well as in studying the folding pathways of macromolecules like proteins. The problem of finding the saddle points on a high dimensional potential energy surface is transformed into the problem of finding decomposition points of its corresponding nonlinear dyna...

Quartic force fields for the ground electronic states of the most stable C4 radical isomers [l-C4(X 3 g ) and r-C4(X Ag)] are computed at the same level of theory. These computations are performed using interaction configuration ab initiomethods and the cc-pVTZ basis set. These force fields on symmetry-adapted coordinates are derived from full six-dimensional potential energy surfaces generated...

We present some new theoretical and computational results for the stationary points of bulk systems. First we demonstrate how the potential energy surface can be partitioned into catchment basins associated with every stationary point using a combination of Newton-Raphson and eigenvector-following techniques. Numerical results are presented for a 256-atom supercell representation of a binary Le...

A femtosecond negative ion-neutral-positive ion charge reversal apparatus has been developed, following the concept of Wöste and Berry, to carry out spectroscopy of transient neutral species along the reaction coordinate. We report studies of the ultrafast dynamics of linear Ag3 produced by photodetachment of linear Ag3. The background-free time-resolved multiphoton ionization spectra of Ag3 ta...

Multidimensional Kramers rate theory is employed to examine the influence exerted by double bonds on the kinetics of conformational transitions of single bonds in trans-polybutadiene and poly(transpropenylene). For both molecules, a detailed discussion of the geometric and potential energy factors that determine the transition rates of the various types of single bonds is presented. Single bond...