"after his becoming" or "after he becoming"

[cykirene]

1. After his becoming rich, the media took interest in him.
2. After he becoming rich, the media took interest in him.
3. He becoming rich, the media took interest in him.


As far as I can tell, 'his becoming rich' in 1 serves as a noun phrase. Is that right?

Also, for 3, the first half is a participle phrase. Is it ok to add 'after' in front like in 2? If not why?

[Alan]

1. Yes, you are correct.
2. A nominative absolute of this kind is unnatural, but certainly cannot be preceded by any preposition.