Seems like a bit of confusion here.
Async serial data does not have a frequency.
It has many frequencies, which are dependant on what data is being sent.
Async serial data is a non clocking protocol, which means its not possible to derive
the originating clock rate from the received data, which is why the sending end and the receiving end must agree on the baud rate.
So the question what frequency is 9600 bps is meaningless.