Experimental Studies and Theoretical Predictions for the H + D ₂ → HD + D Reaction

Abstract

The H + H 2 exchange reaction constitutes an excellent benchmark with which to test dynamical theories against experiments. The H + D 2 (vibrational quantum number v = 0, rotational quantum number j = 0) reaction has been studied in crossed molecular beams at a collision energy of 1.28 electron volts, with the use of the technique of Rydberg atom time-of-flight spectroscopy. The experimental resolution achieved permits the determination of fully rovibrational state-resolved differential cross sections. The high-resolution data allow a detailed assessment of the applicability and quality of quasi-classical trajectory (QCT) and quantum mechanical (QM) calculations. The experimental results are in excellent agreement with the QM results and in slightly worse agreement with the QCT results. This theoretical reproduction of the experimental data was achieved without explicit consideration of geometric phase effects.

A fully state- and angle-resolved study of the H+HD→D+H2 reaction: Comparison of a molecular beam experiment to ab initio quantum reaction dynamics

“…These calibrations are essentially determined in the same manner as previously done by Welge and co-workers. 4 The results of the data analysis are the relative state-to-state differential cross sections. To obtain actual numerical values, a single scaling factor taken from the theoretical scattering calculations is multiplied times the experimental results.…”

“…4 -6 A major advance in the design of beam experiments has been the development of the hydrogen Rydberg atom time-of-flight ͑HRTOF͒ detection scheme by Welge and co-workers. 4 The HRTOF technique provides an unparalleled level of resolution in the time-offlight velocity spectrum, which in turn permits very accurate determination of the rovibrationally state-resolved differential cross sections ͑DCS͒. We also note there have been other important recent advances in the molecular beam methodology that have allowed improvements in the resolution and facility of reactive scattering data.…”

High resolution time-of-flight spectrometer for crossed molecular beam study of elementary chemical reactions

“…7 The detailed experimental methods used to study the crossed beam H + D 2 → HD+ H reaction have been described in great detail previously. 8 A detailed description of this technique used for studying molecular photodissociation can also be found in Ref. 9.…”

“…The development of the H atom Rydberg "tagging" time-of-flight technique ͑HRTOF͒ 7 has also provided us with an extremely powerful tool for measurement of state resolved differential cross sections for both unimolecular and bimolecular reactions with unprecedented translational energy resolution and extremely high sensitivity. This technique has been applied successfully to the studies of the important benchmark reaction H + D 2 → HD+ H recently 8 and many important unimolecular dissociation processes. 9 Recent studies on the H 2 O photochemistry, 10 the O͑ 1 D͒ +H 2 reaction 11 and the OH+ D 2 reaction 12 using this technique have further demonstrated the powerfulness of this method in obtaining experimentally the most detailed dynamics of these benchmark systems.…”

Probing Quantum Dynamics of Elementary Chemical Reactions via Accurate Potential Energy Surfaces

“…Welge and coworkers carried out the first rotational state resolved crossed beam experiment on the H + D 2 → HD + D reaction [31,32] using the H atom Rydberg tagging technique which was developed in the early 1990s [33]. HD product ro-vibrational state resolved differential cross sections were measured at different collision energies.…”