Chemistry Working Group

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Oxidants and Chemistry Working Group

All users interested in the GEOS-Chem chemistry scheme and associated processe (photolysis, heterogenous, deposition) are encouraged to subscribe to the chemistry email list (click here for browser sign-up:

Current GEOS-Chem Chemistry Issues (please add yours!)

Isoprene chemistry

I've created a page with some of the recent literature on isoprene chemistry. Please add more papers as they come along! ( MJE Leeds)


HO2 + CH2O

Scheme does not contain the HO2 + CH2O --> Adduct reaction (MJE Leeds)

Hermans, I., et al. (2005), Kinetics of alpha-hydroxy-alkylperoxyl radicals in oxidation processes. HO2 center dot-initiated oxidation of ketones/aldehydes near the tropopause, Journal of Physical Chemistry A, 109(19), 4303-4311.

According to this paper, this reaction is significant when Temperature is below 220K.

--J Mao. 15:00, 10 Aug 2009 (EDT)

near-IR photolysis of HNO4

1. Since FastJX already takes this into account with cross section data at 574nm, we do not need to redo this in calcrate.f.Change line 867 from




2. change the branch ratio of HNO4 photolysis in ratj.d.

Line 13 HNO4+hv->OH+NO3 from 33.3 to 5.0
Line 14 HNO4+hv->HO2+NO2 from 66.7 to 95.0

This is based on Jimenez et al. (Quantum yields of OH, HO2 and NO3 in the UV photolysis of HO2NO2, PHYSICAL CHEMISTRY CHEMICAL PHYSICS, 2005) shows that HO2 yield should be 0.95 and OH yield should be 0.05 for wavelength above 290nm.

This way all the near-IR photolysis will have most weight on HO2 channel(Stark et al., Overtone dissociation of peroxynitric acid (HO2NO2): Absorption cross sections and photolysis products, JOURNAL OF PHYSICAL CHEMISTRY A, 2008).

--J Mao. 11:00, 26 Oct 2009 (EDT)


--Bob Y. 12:15, 22 September 2009 (EDT)