Magnetic Circular Dichroism of Coronene Mononegative and Dinegative Ions
1972; American Institute of Physics; Volume: 57; Issue: 9 Linguagem: Inglês
10.1063/1.1678851
ISSN1520-9032
AutoresP.J. Zandstra, D. J. Scholtens, R.E. Koning,
Tópico(s)Spectroscopy and Quantum Chemical Studies
ResumoThe magnetic circular dichroism (MCD) of the mononegative and dinegative ions of coronene has been measured. The experimental values of A/D and C/D were compared with the values obtained from MO calculations. For the average z component of the electronic orbital angular momentum of the ground state mononegative ion an experimental value of 1.3 ℏ has been estimated. This value should be compared with the theoretical value of 1.7 ℏ, which depends to some extent on the choice of the parameter values used for the calculation. This is the first case in which an electronic orbital angular momentum for a hydro-carbon in its ground state has been found. The degenerate excited states of both ions have electronic orbital angular momenta of the same magnitude. With the exception of the E1g2→2E2u transitions in the mononegative ion, the agreement between experimental and theoretical MCD values in generally very satisfactory. For the E1g2→2E2u transitions the experimental A/D is greater and the C/D smaller than the calculated values. When a set of orthogonalized atomic orbitals is used for the MO calculations or with a free electron model some improvement results. No indication of a Jahn-Teller effect is present.
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