We report the hyperfine-resolved rotational spectrum of the gas-phase phenoxy
radical in the 8−25 GHz frequency range using cavity Fourier transform microwave spectroscopy.
A complete assignment of its complex but well-resolved fine and hyperfine splittings yielded a
precisely determined set of rotational constants, spin-rotation parameters, and nuclear hyperfine
coupling constants. These results are interpreted with support from high-level quantum chemical
calculations to gain detailed insight into the distribution of the unpaired π electron in this
prototypical resonance-stabilized radical. The accurate laboratory rest frequencies enable studies
of the chemistry of phenoxy in both the laboratory and space. The prospects of extending the
present experimental and theoretical techniques to investigate the rotational spectra of isotopic
variants and structural isomers of phenoxy and other important gas-phase radical intermediates
that are yet undetected at radio wavelengths are discussed.
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The necessity of periodic boundary conditions for the accurate calculation of crystalline terahertz spectra
Terahertz vibrational spectroscopy has emerged as a powerful spectroscopic technique, providing valuable information regarding long-range interactions – and associated collective dynamics – occurring in solids. However, the terahertz sciences are relatively nascent, and there have been significant advances over the last several decades that have profoundly influenced the interpretation and assignment of experimental terahertz spectra. Specifically, because there do not exist any functional group or material-specific terahertz transitions, it is not possible to interpret experimental spectra without additional analysis, specifically, computational simulations. Over the years simulations utilizing periodic boundary conditions have proven to be most successful for reproducing experimental terahertz dynamics, due to the ability of the calculations to accurately take long-range forces into account. On the other hand, there are numerous reports in the literature that utilize gas phase cluster geometries, to varying levels of apparent success. This perspective will provide a concise introduction into the terahertz sciences, specifically terahertz spectroscopy, followed by an evaluation of gas phase and periodic simulations for the assignment of crystalline terahertz spectra, highlighting potential pitfalls and good practice for future endeavors.
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- NSF-PAR ID:
- 10322893
- Date Published:
- Journal Name:
- Physical Chemistry Chemical Physics
- Volume:
- 23
- Issue:
- 36
- ISSN:
- 1463-9076
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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We report the hyperfine-resolved rotational spectrum of gas-phase phenoxy radical in the 8–25 GHz frequency range using cavity Fourier transform microwave spectroscopy. A complete assignment of its complex but well-resolved fine and hyperfine splittings has yielded a precisely determined set of rotational constants, spin-rotation parameters, and nuclear hyperfine coupling constants. These results are interpreted with support from high-level quantum chemical calculations to gain detailed insight into the distribution of the unpaired π electron in this prototypical resonance-stabilized radical. The accurate laboratory rest frequencies enable studies of the chemistry of phenoxy in both the laboratory and in space. The prospects of extending the present experimental and theoretical techniques to investigate the rotational spectra of isotopic variants and structural isomers of phenoxy and other important gas-phase radical intermediates yet undetected at radio wavelengths are discussed.more » « less
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- Free Publicly Accessible Full Text
-
Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1039/D1CP02496E
