Free ( Cl ) is only known from its electronic band spectrum obtained in a low - pressure discharge tube .
* ( Cl ) can only exist as ( Cl O ) at low temperatures , a charge - transfer complex from O to ( Cl ) .
Free ( Cl ) is only known from Cl 's electronic band spectrum obtained in a low - pressure discharge tube .
* ( Cl ) can only exist as ( Cl O ) at low temperatures , a charge - transfer complex from O to ( Cl ) .