Student or Learner
"Please accept my application for a position as an assistant at the Chair for XXX. This position drew my interest because...."
Would you have used "this"? "This" struck me as inappropriate when I read it, but I can't explain why. Perhaps it would've been better to write "the said position," although that might be too formal.
It doesn't strike me as inappropriate.
After thinking about "such position", "that position", "the afore mentioned position" and so forth, I guess I would have decided on a passive voice version:
"Please accept my application for a position as an assistant at the Chair for XXX. My interest on this position has been drawn by ..."
or something similar