The He I photoelectron (PE) spectra of stilbene (1), 2,2'-dichlorostilbene (2) 2-amino-2'-chlorostilbene (3), 2,2'-diaminostilbene (4) ,and 2,2'-dinitrostilbene (5), all in their trans configuration are recorded and discussed. The electronic structure of 1-5 can well be described on the basis of the composite molecule method and simple Hiickel molecular orbital (HMO) calculations. Results indic...

The E0 center formed by g-irradiation in crushed quartz has a distribution in the value of the hyperfine fine structure (hfs) constant of 29Si (nuclear spin: I ˆ 1=2) and of the g-factor. The widths of both distributions decreased after annealing. The central line due to the E0center associated with 28Si (I = 0) shows a clear narrowing as to allow the numerical simulation of the distribution of...

A simplified Hückel-type molecular-orbital (MO) model for the valence electrons of saturated hydrocarbons is proposed and the consequent eigenvalue spectrum considered. A first foundational result is obtained, which every chemist “knows”, namely that: alkanes are stable, with half their (Hückeltype MO) eigenvalues positive and half negative.