State-to-state dynamics of elementary chemical reactions using Rydberg H-atom translational spectroscopy

In this review, a few examples of state-to-state dynamics studies of both unimolecular and bimolecular reactions using the H-atom Rydberg tagging TOF technique were presented. From the H2O photodissociation at 157 nm, a direction dissociation example is provided, while photodissociation of H2O at 121.6 has provided an excellent dynamical case of complicated, yet direct dissociation process through conical intersections. The studies of the O(D-1) + H-2 --> OH+H reaction has also been reviewed here. A prototype example of state-to-state dynamics of pure insertion chemical reaction is provided. Effect of the reagent rotational excitation and the isotope effect on the dynamics of this reaction have also been investigated. The detailed mechanism for abstraction channel in this reaction has also been closely studied. The experimental investigations of the simplest chemical reaction, the H-3 system, have also been described here. Through extensive collaborations between theory and experiment, the mechanism for forward scattering product at high collision energies for the H+HD reaction was clarified, which is attributed to a slow down mechanism on the top of a quantized barrier transition state. Oscillations in the product quantum state resolved different cross sections have also been observed in the H+D-2 reaction, and were attributed to the interference of adiabatic transition state pathways from detailed theoretical analysis. The results reviewed here clearly show the significant advances we have made in the studies of the state-to-state molecular reaction dynamics.

Collisional quantum interference effect on rotational energy transfer in an atom-diatom system

The theoretical model of collisional quantum interference (CQI) in intramolecular rotational energy transfer is described in an atom-diatom system, based on the first Born approximation of time-dependent perturbation theory and considering a long-range interaction potential. The relation between differential and integral interference angles is obtained. For the CO A(1)Pi (v = 0)/e(3)Sigma (-)(v = 1)-He collision system, the calculated integral interference angles are consistent with the experimental values. The physical significance of interference angle and the essential factors it depends on as well as the influence of the short-range interaction on CQI are discussed. (C) 2001 Elsevier Science B.V. All rights reserved.

Selective hydrogenation of cyclopentadiene in mono- and bimetallic catalytic hollow-fiber reactors

The mono- and bimetallic catalytic polymeric hollow-fiber reactors were established with catalytic polymeric cellulose acetate (CA) hollow fibers prepared by supporting the polymer-anchored mono- or bimetallic catalyst in/on the inner wall of the hollow fibers. The selective hydrogenation of cyclopentadiene to cyclopentene was efficiently carried out in the above catalytic polymeric hollow-fiber reactors, especially in the NaBH4 reduced bimetallic PVP-Pd-0.5Co/CA hollow-fiber reactor under mild conditions of 40 degrees C and 0.1 MPa. It was found that there was a remarkable synergic effect of palladium and cobalt reduced by NaBH4 in the bimetallic PVP-Pd-0.5Co/CA hollow-fiber reactor, which results in a 97.5% conversion of cyclopentadiene and a 98.4% selectivity for cyclopentene. (C) 2000 Elsevier Science B.V. All rights reserved.

Hollow fibers of yttria-stabilized zirconia (8YSZ) prepared by calcination of electrospun composite fibers

8YSZ fibers were synthesized by calcination of PVP/zirconium oxychloride/yttrium nitrate composite fibers (PVP-Precursor) obtained by electrospinning. Scanning electron microscopy (SEM) indicated that the 8YSZ fibers are hollow and the gas released during organic binder decomposition resulted in the formation of hollow center in fibers