Atmospheric Chemistry of Titan Options

[Juramike]

Here is a "Benzene-O-Vision" graphic showing the amount of benzene and phenyl radicals at high altitudes on Titan. This is based on detections of benzene and phenyl radical (which recombined in the sample chamber to make benzene) using the INMS instrument during closest approach. The numbers are normalized to constant pressure altitude, roughly 1000 km.



The data was taken from Table 1 in: Vuitton et al, Journal of Geophysical Research 113 (2008) E05007. "Formation and distribution of benzene on Titan". doi: 10.1029/2007JE002997 [EDIT 5/24/10: Article freely available here] and overlaid on a map of Titan.

The authors mentioned that the errors in these measurements are 20%.

These detections are well above the detached haze layer. Most are at the same sun azimuth angle. (T23 observation had the lowest angle.) Assuming that the temporal difference is minimal (each dot is from a different flyby), there doesn't appear to be an obvious correlation with latitude.

This graphic does show that benzene is present even waaaay up in the thermosphere and ionosphere.

[Juramike]

The graphic below shows the pattern of dominant reactions that give nitrogenated products in Titan's atmosphere. On the left side are key reactive species, and on the top are "target" species, some of them used to derive the reactive species.



Note that almost all products can be obtained using cyanomethylene carbene (:CH(CN)), although this may or may not be the dominant route.

Also note that almost all products ultimately come from unsaturated hydrocarbon chemistry, which themselves can only form in a relative absence of H2 (see above post.)

Only HCN would really be expected to form in a hydrogen-rich atmosphere. All the other pathways would be shut down due to CH5+ formation.