A 1+1′ resonance-enhanced multiphoton ionization scheme for rotationally state-selective detection of formaldehyde via the a 1A2←X 1A1 transition

Park, Barratt

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https://hdl.handle.net/2142/96878 Copy

Description

Title

A 1+1′ resonance-enhanced multiphoton ionization scheme for rotationally state-selective detection of formaldehyde via the a 1A2←X 1A1 transition

Author(s)

Park, Barratt

Contributor(s)

• Schaefer, Tim
• Wodtke, Alec
• Meyer, Sven
• Krueger, Bastian C.

Issue Date

2017-06-20

Keyword(s)

Small molecules

Abstract

The formaldehyde molecule is an important model system for understanding dynamical processes in small polyatomic molecules. However, prior to this work, there have been no reports of a resonance-enhanced multiphoton ionization (REMPI) detection scheme for formaldehyde suitable for rovibrationally state-selective detection in molecular beam scattering experiments. Previously reported tunable REMPI schemes are either non-rotationally resolved, involve multiple resonant steps, or involve many-photon ionization steps. In the current work, we present a new $1+1'$ REMPI scheme for formaldehyde. The first photon is tunable and provides rotational resolution via the vibronically allowed $mathrm{tilde{A}}$,$^1mathrm{A}_2leftarrowmathrm{tilde{X}}$,$^1mathrm{A}_1$ transition. Molecules are then directly ionized from the $mathrm{tilde{A}}$ state by one photon of 157~nm. The results indicate that the ionization cross section from the $4^1$ vibrational level of the $mathrm{tilde{A}}$ state is independent of the rotational level used as intermediate, to within experimental uncertainty. The $1+1'$ REMPI intensities are therefore directly proportional to the $mathrm{tilde{A}}leftarrowmathrm{tilde{X}}$ absorption intensities and can be used for quantitative measurement of $mathrm{tilde{X}}$-state population distributions. _x000d_

Publisher

International Symposium on Molecular Spectroscopy

Type of Resource

text

Language

eng

Permalink

http://hdl.handle.net/2142/96878

DOI

https://doi.org/10.15278/isms.2017.TK03

Copyright and License Information

Copyright 2017 Barratt Park

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