Spectroscopy and photochemistry of fluorene at a silica gel/air interface

Barbas, John T.; Sigman, Michael E.; Arce, Rafael; Dabestani, Reza

doi:10.1016/s1010-6030(97)00148-2

Cited by 35 publications

(26 citation statements)

References 21 publications

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“…We show that under sunlight irradiation, the excited triplet state of FL ( 3 FL * ), used here as a proxy for more PAHs present in the SML (Barbas et al, ; Barbas et al, ; Fasnacht & Blough, ; Fasnacht & Blough, ), releases a broad variety of saturated and unsaturated oxygenated multifunctional compounds (e.g., m/z 261.04 (C 13 H 9 O 6 ) in the gas phase (Figure ), through a photosensitized process. Figure shows typical profiles of gas phase products formed immediately upon irradiation of FL and DMSO.…”

Section: Resultsmentioning

confidence: 81%

Formation of Toxic Unsaturated Multifunctional and Organosulfur Compounds From the Photosensitized Processing of Fluorene and DMSO at the Air‐Water Interface

et al. 2020

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Polycyclic aromatic hydrocarbons and dimethyl sulfoxide (DMSO) are ubiquitous at the sea surface. Photochemistry at the air‐sea interface is a potentially important source of volatile organic compounds, but the relevant chemical processes are currently not well known. When aqueous solutions containing a mixture of fluorene (FL) and DMSO are irradiated with actinic radiation, a large suite of unsaturated high molecular weight compounds appear in the aqueous phase; a broad variety of saturated and unsaturated oxygenated multifunctional compounds are also observed in the gas phase, most of which are more toxic than FL. A possible sequence of steps leading to some of the observed compounds in aqueous solution as well as in the gas phase is proposed. The reaction pathways initiated by excited triplet state of FL (3FL*) are supported by theoretical calculations of the reaction Gibbs energies. The formation of organosulfur compounds has been observed to occur in the gas and the aqueous phases initiated by the reaction between 3FL* and DMSO. The aforementioned photosensitized chemistry at the water surface can have an important impact on the formation of secondary organic aerosol in marine boundary layer as polycyclic aromatic hydrocarbons and DMSO enriched at the water surface are ubiquitous.

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Section: Resultsmentioning

confidence: 81%

Formation of Toxic Unsaturated Multifunctional and Organosulfur Compounds From the Photosensitized Processing of Fluorene and DMSO at the Air‐Water Interface

et al. 2020

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“…It has also been found that PAHs (anthracene, phenanthrene, fluoranthene, and pyrene) are good acceptors of singlet molecular oxygen, which can then react by an energy transfer mechanism followed by decomposition of thermally unstable peroxide products and formation of various aromatic aldehydes, acids, and quinones (37)(38)(39)(40)(41). Some PAHs, such as fluorene, are not good acceptors of singlet molecular oxygen but readily undergo photolysis at the solid-air interface by an electron transfer mechanism (42). Therefore, it can be postulated that the consumption of PAHs on soot should be related to these processes.…”

Section: Resultsmentioning

confidence: 99%

Key role of organic carbon in the sunlight-enhanced atmospheric aging of soot by O₂

Han

Liu

et al. 2012

Proc. Natl. Acad. Sci. U.S.A.

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Soot particles are ubiquitous in the atmosphere and have important climatic and health effects. The aging processes of soot during long-range transport result in variability in its morphology, microstructure, and hygroscopic and optical properties, subsequently leading to the modification of soot's climatic and health effects. In the present study the aging process of soot by molecular O 2 under simulated sunlight irradiation is investigated. Organic carbon components on the surface of soot are found to play a key role in soot aging and are transformed into oxygen-containing organic species including quinones, ketones, aldehydes, lactones, and anhydrides. These oxygen-containing species may become adsorption centers of water and thus enhance the cloud condensation nuclei and ice nuclei activities of soot. Under irradiation of 25 mW·cm −2 , the apparent rate constants (k 1,obs ) for loss or formation of species on soot aged by 20% O 2 were larger by factors of 1.5-3.5 than those on soot aged by 100 ppb O 3 . Considering the abundance of O 2 in the troposphere and its higher photoreactivity rate, the photochemical oxidation by O 2 under sunlight irradiation should be a very important aging process for soot.

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“…Recent studies found that enhancement of the photoaging of soot by sunlight is caused by the promoted oxidation of the extractable OC, especially PAHs (21,23), which has been proposed to be initiated by the excitation of OC. Such a mechanism is analogous to the self-sensitized photodegradation of PAHs on inert supports such as silica (27)(28)(29), as supported by the similar photochemical reactions of OC on soot and the OC extracted by n-hexane, as well as by the inactiveness of EC under irradiation (21,23).…”

mentioning

confidence: 82%

Role of elemental carbon in the photochemical aging of soot

Bao

Zhang

et al. 2018

Proc. Natl. Acad. Sci. U.S.A.

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Soot, which consists of organic carbon (OC) and elemental carbon (EC), is a significant component of the total aerosol mass in the atmosphere. Photochemical oxidation is an important aging pathway for soot. It is commonly believed that OC is photoactive but EC, albeit its strong light absorption, is photochemically inert. Here, by taking advantage of the different light absorption properties of OC and EC, we provide direct experimental evidence that EC also plays an important role in the photochemical aging of soot by initiating the oxidation of OC, even under red light irradiation. We show that nascent soot, in addition to undergoing photochemical oxidation under blue light with a wavelength of 440 nm, undergoes similar oxidation under red light irradiation of λ = 648 nm (L). However, separated OC (extracted from soot by n-hexane) and EC exhibit little reactivity under L These observations indicate that EC plays a pivotal role in photoaging of soot by adsorbing light to initiate the oxidation of OC. Comparison of in situ IR spectra and photoelectrochemical behaviors suggests that EC-initiated photooxidation of OC proceeds through an electron transfer pathway, which is distinct from the photoaging induced by light absorption of OC. Since the absorption spectra of EC have a much larger overlap with the solar spectra than those of OC, our results provide insight into the chemical mechanism leading to rapid soot aging by organic species observed from atmospheric field measurements.

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Spectroscopy and photochemistry of fluorene at a silica gel/air interface

Cited by 35 publications

References 21 publications

Formation of Toxic Unsaturated Multifunctional and Organosulfur Compounds From the Photosensitized Processing of Fluorene and DMSO at the Air‐Water Interface

Formation of Toxic Unsaturated Multifunctional and Organosulfur Compounds From the Photosensitized Processing of Fluorene and DMSO at the Air‐Water Interface

Key role of organic carbon in the sunlight-enhanced atmospheric aging of soot by O₂

Role of elemental carbon in the photochemical aging of soot

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Spectroscopy and photochemistry of fluorene at a silica gel/air interface

Cited by 35 publications

References 21 publications

Formation of Toxic Unsaturated Multifunctional and Organosulfur Compounds From the Photosensitized Processing of Fluorene and DMSO at the Air‐Water Interface

Formation of Toxic Unsaturated Multifunctional and Organosulfur Compounds From the Photosensitized Processing of Fluorene and DMSO at the Air‐Water Interface

Key role of organic carbon in the sunlight-enhanced atmospheric aging of soot by O2

Role of elemental carbon in the photochemical aging of soot

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Key role of organic carbon in the sunlight-enhanced atmospheric aging of soot by O₂