Millimeter-millimeter-wave Double-modulation Double-resonance Spectroscopy

Zingsheim, Oliver

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https://hdl.handle.net/2142/111391 Copy

Description

Title

Millimeter-millimeter-wave Double-modulation Double-resonance Spectroscopy

Author(s)

Zingsheim, Oliver

Contributor(s)

• Schlemmer, Stephan
• Thorwirth, Sven
• Lewen, Frank
• Müller, Holger S.P.
• Bonah, Luis

Issue Date

2021-06-22

Keyword(s)

Instrument/Technique Demonstration

Abstract

Complex organic molecules (COMs) show regularly very rich spectra, sometimes at a line density close to the confusion limit. The plethora of lines often originates from the presence of different conformers and/or low-lying vibrational states. The analysis of spectra may considerably be further complicated by vibration-rotation or other interactions. However, accurate spectroscopic predictions in the millimeter-wave (MMW) region are essential for identifying molecules in space. Double-resonance techniques can help to solve these challenges. We present first MMW$-$MMW double-resonance (DR) spectra to unambiguously assign weak and perturbed rotational lines of propanal (C$_2$H$_5$CHO). As already shown in chirped pulse Fourier transform microwave (CP-FTMW)\footnote{D. Schmitz et al., \textit{J. Phys. Chem. Lett.} \textbf{6} (2015) 1493} and in MW$-$MMW DR experiments,\footnote{K.~M. Roenitz et al., \textit{J. Phys. Chem. A.} \textbf{122} (2018) 6321} the Autler-Townes splitting\footnote{S. H. Autler and C. H. Townes, \textit{Phys. Rev.} \textbf{100} (1955) 703} allows for distinguishing between regressive or progressive energy level schemes. The Autler-Townes splitting is clearly visible in our 2D spectra. Furthermore, implementation of a double-modulation double-resonance (DM-DR) technique, pulse modulation of the pump and frequency modulation of the probe source, allows for confusion- and baseline-free spectra containing only the line(s) of interest. We discuss details of the observed Autler-Townes splitting, benefits of simplified spectra, and possible future applications, such as automatization.

Publisher

International Symposium on Molecular Spectroscopy

Type of Resource

Text

Language

eng

Permalink

http://hdl.handle.net/2142/111391

DOI

10.15278/isms.2021.TI13

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