The Hydrogen Games and Other Adventures in Chemistry

Abstract

I seem to have started off on the wrong foot in life, but I am extremely fortunate that I soon found my footing in the company of physical chemists. I consider myself to be very lucky to be doing something that constantly brings me in contact with bright minds, stimulating conversations, and exciting experiments. My work has allowed me to learn astounding facts about the molecules and atoms that make up our surroundings and ourselves. For this article, I focus on one aspect of my research, understanding the fundamental principles of the simple reaction between a hydrogen atom and a hydrogen molecule. Although my group and others have been studying this seemingly simple reaction for well over 30 years, it continues to provoke questions about the properties of matter.

Is the simplest chemical reaction really so simple?

“…Study of this benchmark system and its related isotopic cousins has led to a number of firsts in reaction dynamics: the first potential energy surface with chemical accuracy (less than 1 kcal/mol deviation over the surface), the concept of a transition state, the idea of quantum tunneling in reaction dynamics, the use of transition-state theory to predict reaction rates, the concept of resonances in the reactive scattering cross-section, etc. (1)(2)(3). The extension of these concepts to the F + HD and Cl + HD reactions has also been very fruitful (4,5).…”

“…To answer this question, we conducted experiments on the related reaction H + D 2 → HD + D, in which the deuterium atom D is a heavy isotope of the hydrogen atom having one additional neutron in its nucleus (3). The use of isotopes allows us to distinguish readily the products from the reactants.…”

High resolution crossed molecular beams study of the H+HD→H2+D reaction

“…xmyang@dicp.ac.cn, xawang@ustc.edu.cn our understanding of chemical reaction dynamics [8][9][10][11][12][13]. Futhermore, the hydrogen-atom exchange reaction has also played an important role in the development of many key concepts in reaction dynamics [1,2,4,6,14,15].…”

Coherent superposition of M-states in a single rovibrational level of H2 by Stark-induced adiabatic Raman passage

“…To compare a benchmark atom-diatom scattering experiment (H + H 2 ) with theory without the statistical averaging over a thermal distribution of initial states, there is much interest in preparing the target molecule (H 2 ) in a well-defined rovibrational M-eigenstate, |vJ M . 1 For this purpose we report the preparation of H 2 molecules in a molecular beam in a coherent superposition of eigenstates for a particular rovibrational level, (v = 1, J = 2). A coherent superposition of input channels might allow us to observe the geometrical phase effect which is otherwise hidden by the thermal averaging over uncorrelated initial (v, J, M) states.…”