What are the allowed transitions in the pure rotational spectra of CO2 molecule?

[Shivpal]

I know that the selection rule is :
\DeltaJ = +/- 1

but our prof said that according to some quantum mechanical calculations the odd values of J are not allowed. So, the allowed transitions are :
J 0 <-> 1 ; 2 <-> 3 ; 4 <-> 5... as the odd(1,3,5..) states will not be populated(hence contradicting his own statement)... and no transitions as J 1 -> 2 ; 3 -> 4 ...

I raised the question in the class but he seemed a bit more confused after my question.

Can anyone confirm the authentication of his statements. And Please tell me what is right and what is wrong. Thanx.

 

[Awatarn]

Never heard that
Check it at
http://en.wikipedia.org/wiki/Selection_rule

 

[Shivpal]

...I checked everything on the internet (starting with wiki), and then asked the question here...by the way i got the answer...thanks for showing concern...