Articles | Volume 15, issue 13
Atmos. Chem. Phys., 15, 7195–7202, 2015
https://doi.org/10.5194/acp-15-7195-2015
Atmos. Chem. Phys., 15, 7195–7202, 2015
https://doi.org/10.5194/acp-15-7195-2015

Research article 01 Jul 2015

Research article | 01 Jul 2015

A simple formulation of the CH2O photolysis quantum yields

E.-P. Röth1 and D. H. Ehhalt2 E.-P. Röth and D. H. Ehhalt
  • 1Institute for Energy and Climate Research (IEK-7: Stratosphere), Research Center Jülich, Jülich, Germany
  • 2Institute for Energy and Climate Research (IEK-8: Troposphere), Research Center Jülich, Jülich, Germany

Abstract. New expressions for the wavelength-dependent photolysis quantum yields of CH2O, Φj, are presented. They are based on combinations of functions of the type Ai/(1+exp[−(1/λ − 1/λ0i)/bi]). The parameters Ai, bi, and λ0i which have a physical meaning, are obtained by fits to the measured Φj data available from literature. The altitude dependence of the photolysis frequencies resulting from the new quantum yield expressions are compared to those derived from the Φj recommended by JPL and IUPAC.

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We present a new way to formulate the quantum yields of formaldehyde with several advantages. The formulation is simpler and has fewer parameters than those used so far, and the parameters have a physical meaning. It provides a template for the formulation of other quantum yields, e.g., of the isotopologues of formaldehyde. In addition, we offer a careful review of published measurements. It is also advantageous that the formulation can easily be modified to include temperature effects.
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