Nederlandse Organisatie voor Wetenschappelijk Onderzoek (NWO)
Hydrogen is the most abundant element of the universe, and the third-most abundant element on earth. Hydrogen forms compounds with more chemical elements than any other element of the periodic table. Reactions involving the transfer of H or H+ are important to a range of chemical subfields, including atmospheric, combustion, and interstellar chemistry, and the chemistry of life. The goal of the research program is to push our fundamental understanding of complex chemical reactions involving hydrogen to a significantly higher level. This requires a quantum approach to the hydrogen motion, and the hardware and computational methods needed in such an approach are now available. In the research we ask funding for a set of two novel, complementary methods - a new version of quantum transition state theory and the time-dependent wave packet method - will be further developed and applied to three types of reactions that are representative of a broad range of important chemical reactions involving hydrogen, with applications mainly to atmospheric and interstellar chemistry. These are (i) the reaction of two molecules with each other on an ice surface involving proton transfer, (ii) the gas phase four-atom reaction of oriented OH with CO, and (iii) the radiative association of C+ and H2 producing CH2+. Key questions considered in the projects are: does the proton transfer between two reactant molecules on ice occur directly from one molecule to the other, or through the ice lattice? Can OH react with CO if its H atom points to CO, by a mechanism in which a long-lived collision complex is formed first? Does the radiative association of C+ and H2 take place by vibrational radiative transitions, or are electronic transitions more important? All three projects are highly challenging, in that reactions of such complexity have not been studied before by quantum theories. The projects we ask funding for are to be carried out by two postdocs (to work on their projects for three years each) and one PhD student. The first project (bimolecular reactions on ice surfaces involving proton transfer) will concern atmospherically important reactions. We are planning to complement this project with research on astrochemically important reactions on amorphous ice surfaces, to be carried out in a three-year postdoc project on funding from van Dishoeck's Spinoza price. The second project is of both atmospheric and astrophysical interest, whereas the third project is of astrophysical interest.