Direct optical enrichment of nuclear spin isomers of molecules

A novel enrichment method for nuclear spin isomers of polyatomic molecules is proposed. The method is based on the optical excitation of spin isomers to an upper vibrational or electronic state which is efficiently mixed by i ntramolecular interactions with different nuclear spin states. Under approp riate conditions, the proposed method allows the conversion of almost all m olecules into a single nuclear spin state. (C) 1998 Elsevier Science B.V. A ll rights reserved.