Quantum state-resolved gas/surface reaction dynamics probed by reflection absorption infrared spectroscopy

Abstract

We report the design and characterization of a new molecular-beam/surface-science apparatus for quantum state-resolved studies of gas/surface reaction dynamics combining optical state-specific reactant preparation in a molecular beam by rapid adiabatic passage with detection of surface-bound reaction products by reflection absorption infrared spectroscopy (RAIRS). RAIRS is a non-invasive infrared spectroscopic detection technique that enables online monitoring of the buildup of reaction products on the target surface during reactant deposition by a molecular beam. The product uptake rate obtained by calibrated RAIRS detection yields the coverage dependent state-resolved reaction probability S(θ ). Furthermore, the infrared absorption spectra of the adsorbed products obtained by the RAIRS technique provide structural information, which help to identify nascent reaction products, investigate reaction pathways, and determine branching ratios for different pathways of a chemisorption reaction. Measurements of the dissociative chemisorption of methane on Pt(111) with this new apparatus are presented to illustrate the utility of RAIRS detection for highly detailed studies of chemical reactions at the gas/surface interface. © 2013 AIP Publishing LLC.

Quantum state resolved gas–surface reaction dynamics experiments: a tutorial review

“…11. 16 The adsorbates on the surface will absorb IR light when the frequency is in resonance with a vibrational transition, leading to a decrease in the detected infrared intensity. Taking the ratio of the spectrum measured during the molecular beam deposition with a background spectrum recorded before the start of the deposition for a clean surface produces the final RAIR spectrum.…”

Bond-Selective and Mode-Specific Dissociation of CH3D and CH2D2 on Pt(111)

“…22 Therefore, we only briefly summarize its most important features and the experimental procedure used here. A triply differentially pumped molecular beam source is coupled to a UHV camber containing a single crystal surface mounted on a home-built four-axis manipulator.…”

Quantum state resolved molecular beam reflectivity measurements: CH4 dissociation on Pt(111)

“…The experimental apparatus has been described in detail previously 48 and only the most relevant features will be presented here. The setup consists of a differentially pumped molecular beam source attached to an ultrahigh vacuum (UHV) surface science chamber, with a base pressure of 5 × 10 −11 mbar.…”