Rincón, Angela G. and Guzmán, Marcelo I. and Hoffmann, M. R. and Colussi, A. J. (2010) Thermochromism of Model Organic Aerosol Matter. Journal of Physical Chemistry Letters, 1 (1). pp. 368-373. ISSN 1948-7185 http://resolver.caltech.edu/CaltechAUTHORS:20100526-092341428
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Laboratory experiments show that the optical absorptivity of model organic matter is not an intrinsic property, but a strong function of relative humidity, temperature, and insolation. Suites of representative polyfunctional C_(x)H_(y)O_(z) oligomers in water develop intense visible absorptions upon addition of inert electrolytes. The resulting mixtures reach mass absorption cross sections σ(532 nm) ~ 0.1 m^(2)/gC in a few hours, absorb up to 9 times more solar radiation than the starting material, can be half-bleached by noon sunlight in ~ 1 h, and can be repeatedly recycled without carbon loss. Visible absorptions red-shift and evolve increasingly faster in subsequent thermal aging cycles. Thermochromism and its strong direct dependences on ionic strength and temperature are ascribed to the dehydration of >CH−C(OH)< groups into >C═C< unsaturations by a polar E1 mechanism, and bleaching to photoinduced retrohydration. These transformations are deemed to underlie the daily cycles of aerosol absorption observed in the field, and may introduce a key feedback in the earth’s radiative balance.
|Additional Information:||© 2010 American Chemical Society. Received Date: October 26, 2009; accepted Date: December 2, 2009; Published on Web Date: December 09, 2009. This project was financially supported by the National Science Foundation (ATM-0714329). A.G.R. acknowledges financial support from the Swiss National Science Foundation (PBL2-110274).|
|Official Citation:||Thermochromism of Model Organic Aerosol Matter Angela G. Rincn, Marcelo I. Guzmn, M. R. Hoffmann, A. J. Colussi The Journal of Physical Chemistry Letters 2010 1 (1), 368-373|
|Usage Policy:||No commercial reproduction, distribution, display or performance rights in this work are provided.|
|Deposited By:||Jason Perez|
|Deposited On:||27 May 2010 18:20|
|Last Modified:||26 Dec 2012 12:04|
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