I know that the selection rule is : [tex]\Delta[/tex]J = +/- 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.