A new supersonic molecular beam-surface scattering apparatus permits eigenstate-resolved measurements of gas-surface reactivity. Infrared light from a narrow-bandwidth tunable laser intersects a supersonic molecular beam and prepares an ensemble of molecules in a single rotational and vibrational quantum state. The energized molecules, with their well-defined translational, vibrational, and rotational energies, pass into an ultrahigh vacuum chamber and impinge on a single crystal metal surface where their reactivity is quantified. The apparatus provides independent control over translational, vibrational, and rotational degrees of freedom and permits highly detailed studies of gas-surface reactivity. In this article we describe the design and characterization of our apparatus and illustrate its use to study the dissociative chemisorption of methane on Ni(100).
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