I've been trying to reconcile the two competing models, sublimation vs the ECH but just can't find a coherent explanation of the sublimation model.
Can any of the "mainstreamers" here able to point me towards the currently excepted model for sublimation from a comet?
Yes, you linked to part of it yourself, Sol:
http://www.aanda.org/10.1051/0004-6361/201525925
If you want to go back some time to show that this is really H20 that is being dissociated, then look here:
http://www.hou.usra.edu/meetings/lpsc2015/pdf/2494.pdf
The VIRTIS measurements detected the spectral line of water. Not OH. And if you read the paper carefully, you will see that their measurements were made of emissions coming from a distance of 0 - ~500m from the comet.
If you doubt that the OH that is being produced is OH+ (as would be expected from photodissociation) and not Thornhill's loony idea, which I've highlighted before, which expects an OH- ion, then there is plenty of stuff out there, such as here:
http://authors.library.caltech.edu/22348/
Strange, isn't it. I can't seem to find a coherent explanation of the EU model. At least, not one that agrees with actual observations. And when I point this out, your cobber Haig links to some nonsense in an attempt to claim that negative = positive. Very strange.
tl;dr? EU requires OH- to be produced from the non-existent silicate rock. It then requires a proton (H+) from the solar wind to combine with the OH- to form H20. That is Thornhill's fantasy for the observed water. Except a) the OH observed is positive, and b) there are nowhere near enough protons in the solar wind to account for the amount of H20 observed. As has been shown.
ETA:
The following may also help in the understanding that Thornhill's explanation for the water observed is wrong:
http://onlinelibrary.wiley.com/doi/10.1029/2002GL016840/pdf
In this they discuss the detections of various species at 19P/Borrelly, but the most important, for this discussion, are H2O+ and OH+. No mention of OH-, which is required if Thornhill's explanation is to be correct. Not to mention an increase in solar wind H+ density of about 10 000 000 times its measured value.