Near-ultraviolet and visible optical properties of secondary organic aerosols and gas phase species

dc.check.entireThesisEntire Thesis Restricted
dc.check.opt-outYesen
dc.check.reasonThis thesis is due for publication or the author is actively seeking to publish this materialen
dc.contributor.advisorVenables, Deanen
dc.contributor.authorWilson, Eoin
dc.contributor.funderScience Foundation Irelanden
dc.date.accessioned2017-01-26T12:48:44Z
dc.date.issued2016
dc.date.submitted2016
dc.description.abstractThe interaction of light and gas and particle phase species plays an important role in climate change. Incoherent Broadband Cavity-Enhanced Absorbed Spectroscopy (IBBCEAS) was used to measure the gas phase absorption cross section of a number of atmospherically-relevant species and to investigate the optical properties. The investigated spectral region extended from 325 to 420 nm. Gas phase absorption cross section spectra of biacetyl, 1-nitronaphthalene, 2- nitrophenol, acetaldehyde and acenaphthylene were measured. The gas phase spectra of 1-nitronaphthalene and acenaphthylene have not previously been reported, while the 2-nitrophenol and acetaldehyde absorption cross sections agreed closely with previous literature values. In addition, the absorption of water in the near-UV region was also investigated. In contrast to a recently report, no water vapour absorption was seen; however, upper limits were established for the water absorption cross section at a resolution of 0.5 nm. The optical properties of secondary organic aerosols (SOA) formed by ozonolysis of α-pinene were studied. The refractive index values for α-pinene/O3 SOA ranged from 1.40 at 410 nm to 1.43 at 320 nm, and are broadly consistent with previously reported values. The VOC precursor concentration, relative humidity, and the extent of oxidation were all found to affect the refractive index values. SOA formed from photochemical reaction of 2-NP was investigated. Nitro-aromatic SOA has been proposed to have a large impact on the UV irradiance in urban areas. The 2-NP loss rate followed second order kinetics which indicated that photolysis was not the only loss mechanism; this finding provided evidence for a proposed mechanism. Addition of acetaldehyde to the reaction suppressed particle formation. Off-line UV/Vis absorption measurements showed that SOA absorption increased towards shorter wavelengths, as is typical of brown carbon. The mass absorption coefficient and imaginary part of the complex refractive index indicate that these SOA species are relatively weakly absorbing.en
dc.description.sponsorshipScience Foundation Ireland (SFI Grant FP/11/GEO3200)en
dc.description.statusNot peer revieweden
dc.description.versionAccepted Version
dc.format.mimetypeapplication/pdfen
dc.identifier.citationWilson, E. 2016. Near-ultraviolet and visible optical properties of secondary organic aerosols and gas phase species. PhD Thesis, University College Cork.en
dc.identifier.endpage228en
dc.identifier.urihttps://hdl.handle.net/10468/3525
dc.language.isoenen
dc.publisherUniversity College Corken
dc.rights© 2016, Eoin Wilson.en
dc.rights.urihttp://creativecommons.org/licenses/by-nc-nd/3.0/en
dc.subjectOptical propertiesen
dc.subjectSecondary organic aerosolsen
dc.subjectIBBCEASen
dc.subjectSpectroscopyen
dc.subjectAtmospheric monitoringen
dc.subject2-nitrophenolen
dc.subjectAlpha-pineneen
dc.thesis.opt-outfalse
dc.titleNear-ultraviolet and visible optical properties of secondary organic aerosols and gas phase speciesen
dc.typeDoctoral thesisen
dc.type.qualificationlevelDoctoralen
dc.type.qualificationnamePhD (Science)en
ucc.workflow.supervisord.venables@ucc.ie
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