Photochemistry of flourine in the mesosphere of Venus

In the laboratory, reactions with flourine species proceed rapidly with high rates but under mesospheric conditions the effeciency of these compounds is low due to the rapid formation of HF and to the lack of reactivity of this species. Even if diffusion processes are included, the result of calculations leads to fluorie concentrations typically less than 20 cm^?3. The low photodissociation coeffecient of HF leads to the expectation of a scale height of HF greater than or equal to the mean scale height. If the troposphere appears to be a sink for hydrofluoric acid, the maximum value of fluorine is obtained with a downward flux of 1.3 × 10⁸ HF atoms cm^?2 sec^?1 at the level of the clouds.