Joseph P. Messinger's research works | Yale University and other places

This page lists works of an author who doesn't have a ResearchGate profile or hasn't added the works to their profile yet. It is automatically generated from public (personal) data to further our legitimate goal of comprehensive and accurate scientific recordkeeping. If you are this author and want this page removed, please let us know.

Benzonitrile as a Proxy for Benzene in the Cold ISM: Low-temperature Rate Coefficients for CN + C₆H

Article

March 2020

46 Reads

7 Citations

The Astrophysical Journal Letters

The low-temperature reaction between CN and benzene (C₆H₆) is of significant interest in the astrochemical community due to the recent detection of benzonitrile, the first aromatic molecule identified in the interstellar medium (ISM) using radio astronomy. Benzonitrile is suggested to be a low-temperature proxy for benzene, one of the simplest aromatic molecules, which may be a precursor to polycyclic aromatic hydrocarbons. In order to assess the robustness of benzonitrile as a proxy for benzene, low-temperature kinetics measurements are required to confirm whether the reaction remains rapid at the low gas temperatures found in cold dense clouds. Here, we study the C₆H₆ + CN reaction in the temperature range 15–295 K, using the well-established CRESU technique (a French acronym standing for Reaction Kinetics in Uniform Supersonic Flow) combined with pulsed-laser photolysis-laser-induced fluorescence. We obtain rate coefficients, k(T), in the range (3.6–5.4) × 10⁻¹⁰ cm³ s⁻¹ with no obvious temperature dependence between 15 and 295 K, confirming that the CN + C₆H₆ reaction remains rapid at temperatures relevant to the cold ISM.

Benzonitrile as a proxy for benzene in the cold ISM: low temperature rate coefficients for CN + C

_6

H$_6

Preprint

March 2020

23 Reads

The low temperature reaction between CN and benzene (C $_6$ H $_6$ ) is of significant interest in the astrochemical community due to the recent detection of benzonitrile, the first aromatic molecule identified in the interstellar medium (ISM) using radio astronomy. Benzonitrile is suggested to be a low temperature proxy for benzene, one of the simplest aromatic molecules, which may be a precursor to polycyclic aromatic hydrocarbons (PAHs). In order to assess the robustness of benzonitrile as a proxy for benzene, low temperature kinetics measurements are required to confirm whether the reaction remains rapid at the low gas temperatures found in cold dense clouds. Here, we study the C $_6$ H $_6$ + CN reaction in the temperature range 15--295 K, using the well-established CRESU technique (a French acronym standing for Reaction Kinetics in Uniform Supersonic Flow) combined with Pulsed Laser Photolysis-Laser-Induced Fluorescence (PLP-LIF). We obtain rate coefficients, k(T), in the range (3.6--5.4) $\times$ 10 $^{-10}$ cm $^3$ s $^{-1}$ with no obvious temperature dependence between 15--295 K, confirming that the CN + C $_6$ H $_6$ reaction remains rapid at temperatures relevant to the cold ISM.

Cavity ringdown spectroscopy of intermediates in the reactions of aromatics + OH

Conference Paper

August 2019

23 Reads

Arom. compds., such as toluene and benzene, are important anthropogenically emitted volatile org. compds. in urban areas, and lead to the prodn. of secondary org. aerosols. However, there are many questions that remain about the mechanism of their atm. oxidn. and very few direct observations of the radial intermediates have been made. Therefore, we have used mid-IR pulsed-laser photolysis cavity ringdown spectroscopy to directly detect the hydroxy-cyclohexadienyl radicals formed from the addn. of OH to toluene and benzene in lab. expts. Vibrational spectra and kinetic models of the reaction chem. will be presented.

... Article likely due to oxidation of NA. 20 Yet, a simultaneous growth of a negative absorption band at 1704 cm −1 , also attributed to the stretching mode of C�O functional groups, indicates a loss of mass due to fractionation or decarboxylation of the complex sample, leading to VOC and CO 2 formation. 33,55,56 Slight positive absorptions at 1404 and 1370 cm −1 , corresponding to the bending modes of aldehydic C−H and O−H product functional groups, further support these observations. 20 These simultaneous processes of oxidation and decarboxylation offset one another, resulting in no measurable mass change in the QCM. Figure 7B shows the vibrational spectroscopy results of 1:5 m-DOM/NA thin film, where distinct features of oxygenated product formation are identified. ...
Reference:
Photooxidation of Nonanoic Acid by Molecular and Complex Environmental Photosensitizers

Structures and Chemical Rearrangements of Benzoate Derivatives Following Gas Phase Decarboxylation

Citing Article
September 2022

Journal of the American Society for Mass Spectrometry

[...]

... The importance of halogen bonded complexes have also been reported for the halogen exchange reaction in (HOCl)···(I − ) aq and were explored spectroscopically. 27 Here, with AIMD simulations, we report the microscopic details of Cl 2 formation at acidic pH. Interestingly, under neutral pH condition, although Cl 2 forms transiently, it was not released in the subsequent process. ...
Reference:
Formation of Chlorine in the Atmosphere by Reaction of Hypochlorous Acid with Seawater

Preparation and Characterization of the Halogen-Bonding Motif in the Isolated Cl – ·IOH Complex with Cryogenic Ion Vibrational Spectroscopy

Citing Article
March 2022

The Journal of Physical Chemistry Letters

[...]

... The rotational emission from these unambiguously detected PAHs has been observed towards TMC-1 and originates from CN-functionalized PAHs (nitriles), with the exception of the asymmetric, pure PAH indene. It has been proposed that, owing to their large dipole moments, nitrile-substituted PAHs can be used as observational proxies for pure PAHs 23,24 . Extracting quantitative abundances of unsubstituted PAHs from these proxies, however, relies on knowledge of the kinetics of their dominant formation and destruction pathways 25 . ...
Reference:
Detections of interstellar aromatic nitriles 2-cyanopyrene and 4-cyanopyrene in TMC-1

Rate Constants of the CN + Toluene Reaction from 15 – 294 K and Interstellar Implications

Citing Article
September 2020

The Journal of Physical Chemistry A

[...]

... 25 Recently, the detection of cyanobenzene and cyanonaphthalene in the molecular cloud TMC-1 via radioastronomy confirms the existence of cyano-substituted PAHs (CN-PAHs), 26,27 molecules where a CN group replaces one of the peripheral hydrogens, in astronomical sources. This, in combination with the launch of JWST, has led to a surge in interest in the spectroscopy of CN-PAHs, [28][29][30][31][32][33][34][35] particularly for the CN stretch region (∼2300 cm −1 ). A few laboratory studies have investigated the absorption spectrum of cyanobenzene, cyanonaphthalene, and cyanoanthracene in Ar-and H 2 O-matrices 36,37 as well as in the gas-phase, 38 but correlation to interstellar environments is left wanting. ...
Reference:
The High-Resolution Far- to Near-Infrared Anharmonic Absorption Spectra of Cyano-Substituted Polycyclic Aromatic Hydrocarbons from 300-6200 cm$^{-1}

Benzonitrile as a Proxy for Benzene in the Cold ISM: Low-temperature Rate Coefficients for CN + C₆H

Citing Article
March 2020

The Astrophysical Journal Letters

... The rotational emission from these unambiguously detected PAHs has been observed towards TMC-1 and originates from CN-functionalized PAHs (nitriles), with the exception of the asymmetric, pure PAH indene. It has been proposed that, owing to their large dipole moments, nitrile-substituted PAHs can be used as observational proxies for pure PAHs 23,24 . Extracting quantitative abundances of unsubstituted PAHs from these proxies, however, relies on knowledge of the kinetics of their dominant formation and destruction pathways 25 . ...
Reference:
Detections of interstellar aromatic nitriles 2-cyanopyrene and 4-cyanopyrene in TMC-1

Benzonitrile as a Proxy for Benzene in the Cold ISM: Low-temperature Rate Coefficients for CN + C 6 H 6

Citing Article
March 2020

The Astrophysical Journal Letters

Joseph P. Messinger’s research while affiliated with Yale University and other places

What is this page?

Publications (13)

Citations (5)