Development and Verification of Conformer-Specific Vibrational Spectroscopy.
1Department of Chemistry and Institute for Molecular Science and Fusion Technology, Kangwon National University, Chuncheon 24341, Korea.
The Journal of Physical Chemistry. A
|October 11, 2021
Summary
Researchers developed a new technique to identify molecular conformers in both neutral and cationic states using infrared resonant vacuum ultraviolet mass-analyzed threshold ionization spectroscopy. This breakthrough advances conformational chemistry by enabling isomer-specific vibrational analysis.
Area of Science:
- Physical Chemistry
- Spectroscopy
- Molecular Structure
Background:
- Conformers exhibit similar vibrational structures in neutral (S0) and cationic (D0) states due to comparable nuclear force fields.
- Existing vibrational spectroscopic techniques primarily identify conformers only in the neutral S0 state.
- There is a need for methods capable of distinguishing conformers across different electronic states.
Purpose of the Study:
- To develop a novel conformer-specific vibrational spectroscopic technique.
- To enable the measurement of identifiable vibrational spectra for individual conformers in both S0 and D0 states.
- To verify the technique's efficacy using gas-phase acetone and oxetane isomers.
Main Methods:
- Development of infrared (IR) resonant vacuum ultraviolet mass-analyzed threshold ionization (VUV-MATI) spectroscopy.
- Measurement of isomer-specific vibrational spectra in both S0 and D0 states.
- Analysis of IR dip VUV-MATI and IR hole-burn VUV-MATI spectra for binary mixtures under supersonic expansion.
Main Results:
- Successfully measured isomer-specific vibrational spectra for acetone and oxetane conformers in both neutral and cationic states.
- The technique allows for the representation of spectra by IR-resonant VUV photoionization and one-photon VUV-MATI spectra of the mixture.
- Relative peak intensities provided insights into solute-solvent interactions based on isomer partial pressures.
Conclusions:
- The developed IR-resonant VUV-MATI spectroscopy is effective for measuring conformer-specific vibrational spectra in both S0 and D0 states.
- This technique overcomes limitations of previous methods by analyzing conformers across electronic states.
- The verified method offers a foundation for advanced conformational chemistry studies.
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