This is sort of a carry over from an earlier thread on Mars' surface radiation but it evolved into talking about shedding Venus' atmosphere with a massive impact. This is an idea I've heard of before, but it seems counterintuitive if it is at all valid.

I would think a big strike (think 100km+ impactor, no rubble piles allowed!) would heat the atmosphere up so that much of it could escape but it's also going to release volatiles from the crust and mantle and make Venus (even more) of a volcanic hell.

My question is, is this idea based on some well known paper or conjecture (like did Clarke mention the idea at some point or something like that?) or is it a space science style urban legend thats been floating around for a while?