Laboratory Optical Spectroscopy of the Phenoxy Radical as a Candidate for Diffuse Interstellar Bands

Araki, Mitsunori; Matsushita, Yuki; Tsukiyama, Koichi

doi:10.1088/0004-6256/150/4/113

Cited by 4 publications

(2 citation statements)

References 27 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The phenoxy radical (C6H5O) has an isoelectronic structure with the thiophenoxy radical for valence electrons. The B 2 A2 ← X 2 B1 electronic transition of C6H5O was investigated by Araki et al (2015), and the upper limit of column density in a diffuse cloud was derived to be large (7 × 10 14 cm −2 ) because of lifetime broadening of lines. The vibronic bands were stronger than the origin band, and the long progression of the 6a symmetric in-plane CCC bending mode appeared.…”

Section: Introductionmentioning

confidence: 99%

Laboratory Optical Spectroscopy of Vibronic Transitions of the Thiophenoxy Radical

Sato

Araki

Oyama

et al. 2020

ApJ

Self Cite

View full text Add to dashboard Cite

The thiophenoxy radical (C6H5S) is a species of possible astrophysical interest due to an electronic transition in a 5000 Å region. The B 2 A2 ← X 2 B1 electronic transition of this radical in the discharge of thiophenol was measured using a cavity ring-down spectrometer. The optical absorption spectrum of this transition was obtained in the range covering from the origin band (0-0) to a frequency of 1750 cm −1 . The vibronic bands in the 400-1700 cm −1 region are stronger than the origin band, suggesting structural difference between the ground and excited electronic states. The prominent progression was assigned to the 6a symmetric in-plane CCC bending mode starting from the 6b 1 0 forbidden band. Band origins of individual bands were determined by analysis of the rotational profiles. Although these vibronic bands were not found in optical spectra of diffuse clouds, the upper limits of the column densities for the thiophenoxy radical in the diffuse clouds toward HD 183143 and HD 204827 were evaluated to be ~4 × 10 13 cm −2 .

show abstract

Section: Introductionmentioning

confidence: 99%

Laboratory Optical Spectroscopy of Vibronic Transitions of the Thiophenoxy Radical

Sato

Araki

Oyama

et al. 2020

ApJ

Self Cite

View full text Add to dashboard Cite

show abstract

“…Probing these aspects of its chemical structure and reaction kinetics has been a primary motivation for spectroscopic studies of phenoxy using a variety of methods. Condensed-phase electron spin resonance (ESR) studies − have confirmed the delocalized nature of the unpaired electron, while anion and neutral photoelectron spectroscopy, − ultraviolet (UV)/visible absorption measurements, ,,− and matrix-isolation infrared (IR) spectroscopy , have provided valuable insight into its thermochemistry and vibronic structure.…”

mentioning

confidence: 99%

Rotational Spectrum of the Phenoxy Radical

Changala,

McCarthy

2024

J. Phys. Chem. Lett.

View full text Add to dashboard Cite

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.

show abstract

Ground and low-lying excited states of phenoxy, 1-naphthoxy, and 2-naphthoxy radicals via anion photoelectron spectroscopy

Kregel

Garand

2018

The Journal of Chemical Physics

View full text Add to dashboard Cite

We present the slow electron velocity map imaging spectroscopy of cryogenically cooled phenoxide, 1-naphthoxide, and 2-naphthoxide anions. The results allow us to examine the ground state and the lowest energy excited state in the corresponding neutral radicals. Care was taken to minimize autodetachment signals in the photoelectron spectra, allowing for more straightforward comparisons with Franck-Condon analyses. The ground states of these three aromatic oxide radicals all have the unpaired electron residing in a π orbital delocalized throughout the molecule. The electron affinity of 1-naphthoxy is measured to be 2.290(2) eV, while that of 2-naphthoxy is measured to be 2.404(2) eV, both of which are higher than that of the smaller phenoxy molecule at 2.253(1) eV. The first excited states have the unpaired electron residing in a more localized σ orbital, yielding measured term energies for the state of 1.237(2) eV in 1-naphthoxy and 1.068(1) eV in 2-naphthoxy, while that of phenoxy is lower at 0.952(1) eV. The calculated Franck-Condon spectra generally showed good agreement with the experimental spectra, yielding assignments of the more active vibrations in each electronic state. Significant autodetachment signals arising from dipole bound states near the ground states of all three radicals were observed in our efforts to avoid them, and comparably less autodetachment signals were observed near the excited states. Besides this type of non-Franck-Condon intensities in the photoelectron spectra, we also observed minor features arising due to vibronic coupling in the ground states of all three radicals.

show abstract

Laboratory Optical Spectroscopy of the Phenoxy Radical as a Candidate for Diffuse Interstellar Bands

Cited by 4 publications

References 27 publications

Laboratory Optical Spectroscopy of Vibronic Transitions of the Thiophenoxy Radical

Laboratory Optical Spectroscopy of Vibronic Transitions of the Thiophenoxy Radical

Rotational Spectrum of the Phenoxy Radical

Ground and low-lying excited states of phenoxy, 1-naphthoxy, and 2-naphthoxy radicals via anion photoelectron spectroscopy

Contact Info

Product

Resources

About