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MO: Fachverband Molekülphysik
MO 20: Poster – Molecular Spectroscopy and Dynamics
MO 20.18: Poster
Wednesday, March 12, 2025, 17:00–19:00, Tent
Simplifying rotational spectra: A broadband double resonance approach in millimeter wave spectroscopy — •Prachi Misra, Luis Bonah, Mariyam Fatima, and Stephan Schlemmer — I. Physikalisches Institut, Universität zu Köln, Köln, Germany
Rotational spectroscopy is an important technique for understanding molecular structures, as rotational constants are directly linked to the molecular mass distribution and interatomic distances. In Cologne, high-resolution rotational spectra are measured using Chirped-Pulse Fourier Transform (CP-FT) spectroscopy1 in gas phase.
Analyzing rotational spectra for complex molecules is often complicated by weak features arising from low-lying vibrationally excited states, hyperfine splitting, and internal rotation. To address these challenges, the well-established technique double-resonance spectroscopy is employed. This method uses a probe radiation source to record spectra while a pump source modifies specific transitions due to the Autler-Townes effect. By identifying the connected transitions we can piece together the energy term diagram experimentally. This technique has previously been implemented using absorption spectroscopy2, and is now adapted for use with CP-FT spectroscopy allowing for broadband coverage, eliminating the need for frequency-by-frequency scanning of both the pump and probe radiation sources. Proof-of-concept experiments conducted in the 75-110 GHz range using a new signal generation and acquisition board on the CP-FT spectrometer3 are presented.
1. Park,G.B.(2016)J.Chem.Phys.,144(20) 2. Zingsheim,O.(2021)J. Mol.Spectrosc.,381,111519 3. Hermanns,M.,(2023)Rev.Sci.Inst.,94(3)
Keywords: Milimeter wave; Double resonance spectroscopy; Spectra