Investigation of collision-induced resonances in nitric oxide using two-color polarization spectroscopy

Chang, Ziqiao

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https://hdl.handle.net/2142/107393 Copy

Description

Title

Investigation of collision-induced resonances in nitric oxide using two-color polarization spectroscopy

Author(s)

Chang, Ziqiao

Contributor(s)

• Lucht, Robert P.
• Satija, Aman

Issue Date

2020-06-26

Keyword(s)

• Lineshapes
• Collisional effects

Abstract

Polarization spectroscopy is a pump-probe technique that utilizes a change in the polarization of the probe beam, due to anisotropic Zeeman state populations created by the pump beam, in order to investigate the line shapes and line strengths of a target molecule. We have developed a two-color laser-induced polarization spectroscopy (TCPS) technique, with independent spectral tuning of the pump and probe beams, for investigating collision induced resonances (CIRs) in nitric oxide (NO). We distinguish CIRs from natural resonances (NRs), which occur when the transitions excited by pump and probe beams share a common upper and/or lower level. CIRs occur because of state-to-state rotational transfer during which the Zeeman state anisotropy is preserved to some extent. In these NO TCPS studies, a circularly-polarized pump beam is tuned to create a Zeeman state anisotropy in the A$^{2}$$\Sigma$$^{+}$-X$^{2}$$\Pi$ (0-0) band of NO molecules. A weak probe beam is then scanned over a range of transitions close to the pump frequency in order to probe NRs and CIRs. Gas mixtures of 1\% NO in the buffer gases N$_{2}$ (Fig. below), He, and Ar were selected for the experiments to investigate the dependence of CIR on collision species. The strongest CIRs were observed in the He buffer gas and the weakest CIRs were observed in the Ar buffer gas. The TCPS technique may also be used for species selective and transition selective NO measurements. \begin{wrapfigure}{l}{0pt} \includegraphics[scale=0.18]{2020_ISMS2.eps} \end{wrapfigure}

Publisher

International Symposium on Molecular Spectroscopy

Type of Resource

Text

Language

eng

Permalink

http://hdl.handle.net/2142/107393

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Copyright 2020 is held by the Author(s)

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