Diamagnetic Raman Optical Activity of Chlorine, Bromine, and Iodine Gases. Issue 10 (4th February 2016)

• Record Type: Journal Article
• Authors: Šebestík, Jaroslav; Kapitán, Josef; Pačes, Ondřej; Bouř, Petr
• Is Part Of: Angewandte Chemie international edition. Volume 55:Issue 10(2016)
• Page Start: 3504
• Page End: 3508
• Publication Date: 2016-02-04
• Subjects: angular momentum theory -- diamagnetic molecules -- excited electronic states -- magnetic field -- Raman optical activity; Chemistry -- Periodicals; 540
• DOI: 10.1002/anie.201600058
• Languages: English
• ISSNs: 1433-7851

Abstract

Abstract: Magnetic Raman optical activity of gases provides unique information about their electric and magnetic properties. Magnetic Raman optical activity has recently been observed in a paramagnetic gas ( Angew. Chem. Int. Ed .2012, 51, 11058; Angew. Chem .2012, 124, 11220). In diamagnetic molecules, it has been considered too weak to be measurable. However, in chlorine, bromine and iodine vapors, we could detect a significant signal as well. Zeeman splitting of electronic ground‐state energy levels cannot rationalize the observed circular intensity difference (CID) values of about 10 −4 . These are explicable by participation of paramagnetic excited electronic states. Then a simple model including one electronic excited state provides reasonable spectral intensities. The results suggest that this kind of scattering by diamagnetic molecules is a general event observable under resonance conditions. The phenomenon sheds new light on the role of excited states in the Raman scattering, and may be used to probe molecular geometry and electronic structure. Abstract : Rotating diamagnetic molecules are supposed not to interact much with external magnetic fields because their magnetic dipole moment is small. However, a strong magnetic Raman optical activity of Cl2, Br2 and I2 gases was measured. This activity was rationalized by paramagnetic excited electronic states participating in the Raman scattering.