Xu Guangzhi

Surface enhanced Raman spectra of carbonate, hydrocarbonate, and substituted acetic acids on silver hydrosols

Abstract The SERS spectra of carbonate, hydrocarbonate and several substituted acetic acids absorbed on silver hydrosols are recorded. The greatest enhancement of E′ modes is shown in the spectrum of carbonate, from which the carbonate is deduced to be absorbed in an “end on” configuration, rather than flat on the surface. The spectrum of the hydrocarbonate solution shows the most enhanced bands at about 925 and 620 cm−1, which cannot be explained clearly. All the substituted acids have a most enhanced bands at about 1630 cm−1, revealing that the acids are initially adsorbed in a single bonding state through the carboxyl group. The change in the SERS spectra of the acids with time indicates that a bidentate bridging adsorbed state may be formed after some time.

He I photoelectron spectroscopic studies of the electronic structure in some forked conjugated systems. Experimental and theoretical studies of the molecular orbital character of the compounds

Abstract The He I photoelectron spectra of thienyl polyenic phenyl ketones and phenyl polyenic thienyl ketones have been studied. To assign these spectra MNDO molecular orbital calculations for the named molecules have also been carried out. The results show that, (a) the reduction of HOMO ionization potentials in the same series of compounds is directly proportional to the number of ethylenic groups in the molecules; (b) the polyenic group conjugates only with the conjoint thienyl ring in the thienyl polyenic phenyl ketones, but in the phenyl polyenic thienyl ketones the polyenic group conjugates only with the conjoint phenyl ring, i.e. the carbonyl group can be considered as an obstructing group for complete molecular conjugation and so there is no conjugated π bond system of the whole molecule; (c) in the compounds the contributions of the atoms from the thienyl ring and from the thienyl ethylenic group to their respective HOMO are large, i.e. the conjugated competitions of the thienyl ring and of the thienyl ethylenic group are stronger than those of the phenyl ring and of phenyl ethylenic group in the respective molecules of these two compounds; (d) there is a conjugated π bond through the conmplete molecule in the compound