Leah Dodson (University of Maryland, Chemistry and Biochemistry)

Date: Thu. November 7th, 2024, 4:00 pm-5:00 pm
Location: Rockefeller 301
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Low-Temperature Reaction Kinetics Tools for Quantum-State-Resolved Chemistry

Many laboratory methodologies have grown out of developments in the field of atomic, molecular, and optical physics that are ripe for breakthrough studies in the hands of physical chemists. Exquisite control over quantum-state populations now enables chemical reactions to be studied to a level of detail not previously attainable. In this talk, I will describe how we have adopted buffer-gas-cooling (sympathetic/collisional cooling) techniques along with radiofrequency ion traps to investigate chemical reactions that depend sensitively on the initial quantum state of the reactants.

I will describe our work to measure reaction rate constants for radiative-association reactions, a special class of chemical reactions that is most relevant under the low-temperature, low-pressure conditions of space. In these experiments, gaseous atomic metal ions are generated in a glow-discharge ion source, mass selected, and trapped in a multipole ion trap. Reaction kinetics are monitored in real time by mass spectrometry. In a parallel experiments we have developed the tools needed to prepare cold neutral molecules—referring to both their rotational and translational energies—and I will describe our successes in producing the neutral co-reactants at 20 K using buffer-gas cooling and probing them spectroscopically using cavity-ringdown spectroscopy. Future directions in measuring collisional cross sections will be discussed.