@article {20877,
	title = {Formation and Optical Properties of Brown Carbon from Small alpha-Dicarbonyls and Amines},
	journal = {Environmental Science \&amp;amp; Technology},
	volume = {53},
	number = {1},
	year = {2019},
	note = {Hg6foTimes Cited:0Cited References Count:75},
	month = {Jan 1},
	pages = {117-126},
	abstract = {Brown Carbon (BrC) aerosols scatter and absorb solar radiation, directly affecting the Earth{\textquoteright}s radiative budget. However, considerable uncertainty exists concerning the chemical mechanism leading to BrC formation and their optical properties. In this work, BrC particles were prepared from mixtures of small alpha-dicarbonyls (glyoxal and methylglyoxal) and amines (methylamine, dimethylamine, and trimethylamine). The absorption and scattering of BrC particles were measured using a photoacoustic extinctometer (405 and 532 nm), and the chemical composition of the alpha-dicarbonyl-amine mixtures was analyzed using orbitrap-mass spectrometry and thermal desorption-ion drift-chemical ionization mass spectrometry. The single scattering albedo for methylglyoxal-amine mixtures is smaller than that of glyoxal-amine mixtures and increases with the methyl substitution of amines. The mass absorption cross-section for methylglyoxal-amine mixtures is two times higher at 405 nm wavelength than that at 532 nm wavelength. The derived refractive indexes at the 405 nm wavelength are 1.40-1.64 for the real part and 0.002-0.195 for the imaginary part. Composition analysis in the alpha-dicarbonyl-amine mixtures reveals N-heterocycles as the dominant products, which are formed via multiple steps involving nucleophilic attack, steric hindrance, and dipole dipole interaction between alpha-dicarbonyls and amines. BrC aerosols, if formed from the particle-phase reaction of methylglyoxal with methylamine, likely contribute to atmospheric warming.},
	keywords = {absorbing aerosols, cavity ring, chemistry, glyoxal, light-absorption, methylglyoxal, particles, products, refractive-index, spectral dependence},
	isbn = {0013-936X},
	author = {Marrero-Ortiz, W. and Hu, M. and Du, Z. F. and Ji, Y. M. and Wang, Y. J. and Guo, S. and Y. Lin and Gomez-Hermandez, M. and Peng, J. F. and Li, Y. X. and Secrest, J. and Zamora, M. L. and Y. Wang and An, T. C. and Zhang, R. Y.}
}
