Significantly Improved Detection of Molecular Oxygen by Two-Color Resonance-Enhanced Multiphoton Ionization

Abstract

We report a new spectroscopic detection scheme for molecular oxygen that achieves roughly two orders of magnitude higher sensitivity for fully rotationally resolved spectra than the current state of the art. Two-color (2 + 1′) resonance-enhanced multiphoton ionization (REMPI) via the 3d Rydberg complex yields state-selective spectra with signal comparable to the intense but diffuse C 3sσ 3 Π g ← X 3 Σ g − (2 + 1) REMPI bands without significant saturation or broadening. The resulting increase in sensitivity permitted observation of the very weak 3dπ 1 Δ 2 ← X 3 Σ g − transitions and is independent of the intermediate state. This advance in ionization efficiency and quantum state-selective sensitivity for O 2 promises to aid physical and chemical studies across a wide variety of fields.Letter pubs.acs.org/JPCL

Vibrational energy transfer in collisions of molecules with metal surfaces

“…Spectroscopic methods for O 2 are subject to the consequences of rapid predissociation in excited electronic states -these consequences must be dealt with for example with picosecond SEP or employing new REMPI detection schemes. 132 The interactions of NO with Cu are also interesting as dissociation is also likely here. As the lightest coinage metal, copper's higher reactivity than silver and gold led early experiments to focus on NO interactions only with oxidized copper due to the difficulty in maintaining clean copper under molecular beam exposure.…”

“…Spectroscopic methods for O 2 are subject to the consequences of rapid predissociation in excited electronic states – these consequences must be dealt with for example with picosecond SEP or employing new REMPI detection schemes. 132 …”