Benzene Rydberg spectrum

M. S. Child The first part of the talk by Prof. Neusser concerned intramolecular interaction between the Si and Ti states of benzene, and the second part referred to the high Rydberg spectrum. Each member of this singlet series must have a corresponding triplet, such that... 

Other experimental evidence leads to essentially the same conclusion regarding the n ionization of pyridine. El Sayed and Kasha (1961) have detected Rydberg series in the absorption spectrum similar to those in benzene and ascribable to n orbitals (9-266 e.v., 02 11-56 e.v., 62) and, in addition, reported a fragmentary series leading to a third ionization potential of 10-3 e.v. which they ascribed to the nitrogen lone pair. Similar values are found by photoelectron spectroscopy which also indicated the 10-3 e.v. (10-54 e.v.) level to be only weakly bonding. 

In Fig. 14 the magnified central part of the spectrum shown in Fig. 13 is presented together with the positions of the Rydberg peaks of two series calculated using Eq. (6). The assignment of the series limits leads to accurate values of the lowest adiabatic ionization energy of the benzene (C6D6> molecule and the rotational constants of its cation [89]. 

The first approximation to the description of Rydberg levels treats the benzene ion-core as a monopole. This description is known not to be quantitatively accurate. Calculations which include the symmetry of the molecular ion, and the charge delocalization, lead to an energy level spectrum in much better agreement with experiment. Thus, it seems unlikely that the geometric structure of the molecular ion can be completely neglected in the study of photoionization. 

Our first use of crystal polarization was in hexamethylbenzene. It had all molecular planes parallel to one another and perpendicular to the main faces of a sublimed crystal. It was known that the lowest absorption system was polarized in the molecular plane, conforming with its assignment to a n-n transition. However in the next system of benzene at 200 nm, corresponding to the hexamethylbenzene system at 230 nm, the vapour phase spectrum had been assigned to a Rydberg transition polarized perpendicular to the molecular plane [210]. 

Benzene has a relatively low ionization potential (9.247 eV or 74580 cm ) so that all transitions from a2u and many from eig will lie beyond it and lead to super-excited states The second 1P ivas shown to belong to the highest filled o orbital It is not our intention to treat the spectrum of benzene in detail we merely used it as an example for the benefit of the non-initiated Reader as a simple MO + Rydberg scheme without energies, vibronic interactions, a electrons, and so on. Since the... 

By application of valence shell electron energy loss spectroscopy, inner shell electron energy loss spectroscopy, magnetic circular dichroism spectroscopy, as well as photoelectron and electron transmission spectroscopy it can be deduced that the ji-electron system of borazine resembles that of benzene [8]. Table 4/13 presents the Rydberg term value matrix and Table 4/14 the energies and assignments from the electron energy loss spectrum (EELS) [8]. 

The bright states of the vertical excitation spectrum of 2-phenylfuran in gas phase are reported in Table 3. The full set of vertical transitions up to 7.4 eV is reported in Table SI of the Online Resource 1. The first two transitions are into a bright and a dark excimer states at 4.66 and 4.98 eV, respectively. The experimental band maximum in this region is at 4.55 eV in hexanes [16] and at 4.44 eV in methanol [45]. After a series of dark transitions into Rydberg states, a second band is characterized by a local nn excitation within the benzene ring (5.98 eV) and a nn excitation delocalized over the whole molecule. A very... 

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