Measurements of the Absorption Cross Section of¹³CHO¹³CHO at Visible Wavelengths and Application to DOAS Retrievals

Abstract

The trace gas glyoxal (CHOCHO) forms from the atmospheric oxidation of hydrocarbons and is a precursor to secondary organic aerosol. We have measured the absorption cross section of disubstituted (13)CHO(13)CHO ((13)C glyoxal) at moderately high (1 cm(-1)) optical resolution between 21 280 and 23 260 cm(-1) (430-470 nm). The isotopic shifts in the position of absorption features were found to be largest near 455 nm (Δν = 14 cm(-1); Δλ = 0.29 nm), whereas no significant shifts were observed near 440 nm (Δν < 0.5 cm(-1); Δλ < 0.01 nm). These shifts are used to investigate the selective detection of (12)C glyoxal (natural isotope abundance) and (13)C glyoxal by in situ cavity enhanced differential optical absorption spectroscopy (CE-DOAS) in a series of sensitivity tests using synthetic spectra, and laboratory measurements of mixtures containing (12)C and (13)C glyoxal, nitrogen dioxide, and other interfering absorbers. We find the changes in apparent spectral band shapes remain significant at the moderately high optical resolution typical of CE-DOAS (0.55 nm fwhm). CE-DOAS allows for the selective online detection of both isotopes with detection limits of ∼200 pptv (1 pptv = 10(-12) volume mixing ratio), and sensitivity toward total glyoxal of few pptv. The (13)C absorption cross section is available for download from the Supporting Information.

Desenvolvimento de um circuito microfluídico para análise atmosférica através de microusinagem com laser de pulsos ultracurtos

“…Através disso, diversos trabalhos têm contribuído fortemente para fornecer um melhor entendimento da grande contribuição do GLI e MGLI na formação de AOS em todo o planeta (KAMPF et al, 2013a;WAXMAN et al, 2013WAXMAN et al, , 2015GOSS et al, 2015;SAREEN et al, 2017). Estudos de captação de GLI para formação de AOS com sais contendo íons de amônio (NH4 + ), que evidênciam formação irreversível de aerossóis com nitrogêniocarbono (NC) considerados como um tipo de aerossol absorvedor de luz conhecido como carbono marrom ou mais comumente BrC "Brown Carbon" (BARNARD; VOLKAMER; KASSIANOV, 2008;GALLOWAY et al, 2009b;NOZIÈRE;DZIEDZIC;CÓRDOVA, 2009).…”