The linear polarizability, a, the first hyperpolarizability, ß, and the second hyperpolarizability, y, of three different classes of basic heterocyclic organic structures have been calculated by the ab inio time-dependent coupled Hartree-Fock-Roothaan method using a 4-31G basis set augmented by diffuse p and d functions.For the a and y coefficients, the calculated orders thiophene > pyrrole > furan for the five-membered rings; pyridine > pyrazole > s-triazine for the aromatic bases; and benzothiazole > oxazole for the fused ring systems show a qualitative relationship with the corresponding order in Ae(HOMO-LUMO) of the respective group of molecules. The ß values do not appear to show a discernible trend. The dispersion of (-; ) and those of y(-;0,0, ), (-\ , ,-), y(-2< ;0, , ), and y(-3 ; , , ) in the case of the five-membered rings are also reported.
Adsorption of phenol on a well defined (0001) surface of ZnO has been investigated with coherent anti-Stokes Raman scattering spectroscopy (CARS) using planar optical waveguide geometry. Monolayer sensitivity was achieved by establishing an interference condition within the ZnO layer to minimize the CARS signal from the film. At relatively higher surface coverages both physisorbed and chemisorbed phenol were present on the surface; however, with continuous pumping of the vacuum chamber all the physisorbed species were removed from the surface. The chemisorbed species is retained as the phenoxide on ZnO (0001) surface.Paper 2/05043I ; Received
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