Rotational Analysis of ν13 of Allyl Radical

DeSain, John D.; Curl, R. F.

doi:10.1006/jmsp.1999.7868

Cited by 7 publications

(4 citation statements)

References 3 publications

(10 reference statements)

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“…In the IR spectrum of He-solvated allyl, we observed rovibrational bands near the band origins previously reported in high resolution gas-phase studies carried out by D.J. Nesbitt and co-workers [83] and R. Curl and co-workers [84][85][86]. In addition to the fundamental CH stretching modes, four other bands were assigned to the allyl radical using a consistent set of rotational constants.…”

Section: Methyl Ethyl Propargyl Allyl and Propyl Radicalssupporting

confidence: 71%

Infrared Spectroscopy of Molecular Radicals and Carbenes in Helium Droplets

Douberly

2022

Topics in Applied Physics

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The helium droplet is an ideal environment to spectroscopically probe difficult to prepare molecular species, such as radicals, carbenes and ions. The quantum nature of helium at 0.4 K often results in molecular spectra that are sufficiently resolved to evoke an analysis of line shapes and fine-structure via rigorous “effective Hamiltonian” treatments. In this chapter, we will discuss general experimental methodologies and a few examples of successful attempts to efficiently dope helium droplets with organic molecular radicals or carbenes. In several cases, radical reactions have been carried out inside helium droplets via the sequential capture of reactive species, resulting in the kinetic trapping of reaction intermediates. Infrared laser spectroscopy has been used to probe the properties of these systems under either zero-field conditions or in the presence of externally applied, homogeneous electric or magnetic fields.

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Section: Methyl Ethyl Propargyl Allyl and Propyl Radicalssupporting

confidence: 71%

Infrared Spectroscopy of Molecular Radicals and Carbenes in Helium Droplets

Douberly

2022

Topics in Applied Physics

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“…We underestimate the absorption of the C-H stretching mode of aliphatic hydrocarbon chains near 3.4 µm (see Bellucci et al 2009;Maltagliati et al 2015). This discrepancy is likely due to incomplete line lists or cross sections in the HITRAN 2016 database for several hydrocarbons such as the allyl radical (C 3 H 5 ; Uy et al 1998;DeSain & Curl 1999), butane (C 4 H 10 ; Abplanalp et al 2019) and methylacetylene (CH 3 CCH; Abplanalp et al 2019). Further, our chemical network lacks some of the higher hydrocarbons for which absorption cross sections exists such as isoprene (C 5 H 8 ; Brauer et al 2014).…”

Section: Appendix C: Representation Of Thick Hazes In Garlicmentioning

confidence: 93%

Detectability of biosignatures on LHS 1140 b

Wunderlich

Scheucher

Grenfell

et al. 2021

A&A

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Context. Terrestrial extrasolar planets around low-mass stars are prime targets when searching for atmospheric biosignatures with current and near-future telescopes. The habitable-zone super-Earth LHS 1140 b could hold a hydrogen-dominated atmosphere, and is an excellent candidate for detecting atmospheric features. Aims. In this study we investigate how the instellation and planetary parameters influence the atmospheric climate, chemistry, and spectral appearance of LHS 1140 b. We study the detectability of selected molecules, in particular potential biosignatures, with the upcoming James Webb Space Telescope (JWST) and Extremely Large Telescope (ELT). Methods. In the first step we used the coupled climate–chemistry model 1D-TERRA to simulate a range of assumed atmospheric chemical compositions dominated by molecular hydrogen (H2) and carbon dioxide (CO2). In addition, we varied the concentrations of methane (CH4) by several orders of magnitude. In the second step we calculated transmission spectra of the simulated atmospheres and compared them to recent transit observations. Finally, we determined the observation time required to detect spectral bands with low-resolution spectroscopy using JWST, and the cross-correlation technique using ELT. Results. In H2-dominated and CH4-rich atmospheres oxygen (O2) has strong chemical sinks, leading to low concentrations of O2 and ozone (O3). The potential biosignatures ammonia (NH3), phosphine (PH3), chloromethane (CH3Cl), and nitrous oxide (N2O) are less sensitive to the concentration of H2, CO2, and CH4 in the atmosphere. In the simulated H2-dominated atmosphere the detection of these gases might be feasible within 20 to 100 observation hours with ELT or JWST when assuming weak extinction by hazes. Conclusions. If further observations of LHS 1140 b suggest a thin, clear, hydrogen-dominated atmosphere, the planet would be one of the best known targets to detect biosignature gases in the atmosphere of a habitable-zone rocky exoplanet with upcoming telescopes.

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Section: Appendix A: Neptune Validationmentioning

confidence: 93%

Detectability of biosignatures on LHS 1140 b

Wunderlich,

Scheucher,

Grenfell

et al. 2020

Preprint

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Context. Terrestrial extrasolar planets around low-mass stars are prime targets when searching for atmospheric biosignatures with current and near-future telescopes. The habitable-zone Super-Earth LHS 1140 b could hold a hydrogen-dominated atmosphere and is an excellent candidate for detecting atmospheric features. Aims. In this study, we investigate how the instellation and planetary parameters influence the atmospheric climate, chemistry, and spectral appearance of LHS 1140 b. We study the detectability of selected molecules, in particular potential biosignatures, with the upcoming James Webb Space Telescope (JWST) and Extremely Large Telescope (ELT). Methods. In a first step we use the coupled climate-chemistry model, 1D-TERRA, to simulate a range of assumed atmospheric chemical compositions dominated by molecular hydrogen (H 2 ) and carbon dioxide (CO 2 ). Further, we vary the concentrations of methane (CH 4 ) by several orders of magnitude. In a second step we calculate transmission spectra of the simulated atmospheres and compare them to recent transit observations. Finally, we determine the observation time required to detect spectral bands with low resolution spectroscopy using JWST and the cross-correlation technique using ELT.Results. In H 2 -dominated and CH 4 -rich atmospheres oxygen (O 2 ) has strong chemical sinks, leading to low concentrations of O 2 and ozone (O 3 ). The potential biosignatures ammonia (NH 3 ), phosphine (PH 3 ), chloromethane (CH 3 Cl) and nitrous oxide (N 2 O) are less sensitive to the concentration of H 2 , CO 2 and CH 4 in the atmosphere. In the simulated H 2 -dominated atmosphere the detection of these gases might be feasible within 20 to 100 observation hours with ELT or JWST, when assuming weak extinction by hazes. Conclusions. If further observations of LHS 1140 b suggest a thin, clear, hydrogen-dominated atmosphere, the planet would be one of the best known targets to detect biosignature gases in the atmosphere of a habitable-zone rocky exoplanet with upcoming telescopes.

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Rotational Analysis of ν13 of Allyl Radical

Cited by 7 publications

References 3 publications

Infrared Spectroscopy of Molecular Radicals and Carbenes in Helium Droplets

Infrared Spectroscopy of Molecular Radicals and Carbenes in Helium Droplets

Detectability of biosignatures on LHS 1140 b

Detectability of biosignatures on LHS 1140 b

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