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High resolution TDL spectroscopy of the Ar-CH4 complex
M Wangler1, D A Roth, V M Krivtsun
1I. Physikalisches Institut, Universität zu Köln, Germany. wangler@ph1.uni-koeln.de
Summary
We analyzed the argon-methane (Ar-CH4) complex spectrum using a tunable diode laser, revealing key ro-vibrational transitions. Experimental findings closely match ab initio predictions, validating our spectral analysis of this weakly bound molecule.
Area of Science:
- Molecular Spectroscopy
- Intermolecular Forces
- Quantum Chemistry
Background:
- The argon-methane (Ar-CH4) complex is a weakly bound van der Waals molecule.
- Understanding its properties provides insights into intermolecular interactions.
- Previous studies have explored its spectral characteristics.
Purpose of the Study:
- To experimentally determine the spectrum of the Ar-CH4 complex in the 7 micrometer region.
- To compare experimental results with theoretical predictions from ab initio calculations.
- To analyze specific ro-vibrational transitions of the methane moiety within the complex.
Main Methods:
- Probing a supersonic gas expansion of Ar-CH4 with a tunable diode laser (TDL).
- Recording and analyzing spectral bands associated with the v4 vibration of CH4.
- Investigating transitions such as j = 1 <-- 0, j = 0 <-- 1, j = 2 <-- 1, and j = 3 <-- 2.
Main Results:
- Several Ar-CH4 bands were recorded and analyzed in the 1295-1330 cm(-1) spectral region.
- Specific transitions, including j=1<--0 at 1311 cm(-1), were identified.
- Experimental spectra showed close agreement with ab initio calculations for gross features and spectral details.
Conclusions:
- The experimental spectrum of the Ar-CH4 complex was successfully obtained and analyzed.
- The study validates the accuracy of ab initio calculations for predicting the spectral properties of Ar-CH4.
- This work enhances the understanding of intermolecular interactions in weakly bound complexes.