Tropospheric Chemistry Modelling Group

Whether an organic molecule will condense on an organic aerosol, will be determined to an important extent by its volatility or vapor pressure. The Capouet-Müller model predicts the vapor pressure of organic molecules. It is based on a simple group contribution approach:

log(p/Torr) = log(phc/Torr)+∑iτi

with p the vapor pressure of the target compound, phc the vapor pressure of its parent hydrocarbon -i.e. the molecule with all its functional groups replaced by hydrogens-, and τi contributions due to functional groups (e.g. hydroxy, carbonyl, acid).

The method was the first of its kind to have the atmospherically relevant hydroperoxides, peracids and peroxy acyl nitrates within its application range.

Despite its simple set-up, the method gave broadly similar results as the detailed method of Nannoolal et al. ( Fluid Phase Eq. , 2008) when applied to the condensable molecules of our chemical mechanism BOREAM (Compernolle et al., 2010).


Capouet, M., J.-F. Müller, A group contribution method for estimating the vapour pressures of α-pinene oxidation products, Atmos. Chem. Phys., 6, 1455-1467, 2006 [Full article].

Compernolle, S., K. Ceulemans, and J.-F. Müller, Technical note: Vapor pressure estimation methods applied to secondary aerosol constituents from α-pinene oxidation: an intercomparison study, Atmos. Chem. Phys., 10, 6271-6282, 2010 [Full article].