title: Diamagnetic Raman Optical Activity of Chlorine, Bromine, and Iodine Gases.
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.
authors: Biomolecular Spectroscopy, Institute of Organic Chemistry and Biochemistry, Flemingovo náměstí 2, 16610, Prague, Czech Republic.
authors: Jaroslav
authors: http://orcid.org/0000-0002-0614-2064
authors: J
authors: Šebestík
authors: Department of Optics, Palacký University, 17. listopadu 12, 77146, Olomouc, Czech Republic.
authors: Josef
authors: J
authors: Kapitán
authors: Biomolecular Spectroscopy, Institute of Organic Chemistry and Biochemistry, Flemingovo náměstí 2, 16610, Prague, Czech Republic.
authors: Ondřej
authors: O
authors: Pačes
authors: Biomolecular Spectroscopy, Institute of Organic Chemistry and Biochemistry, Flemingovo náměstí 2, 16610, Prague, Czech Republic. bour@uochb.cas.cz.
authors: Petr
authors: P
authors: Bouř
keywords: Raman optical activity; angular momentum theory; diamagnetic molecules; excited electronic states; magnetic field