A simple method has been developed to produce SERS-active metal surfaces. Six metal surfaces (cadmium, nickel, gold, iron, copper, and silver) have been prepared on an aluminum foil underlayment by chemical reduction and strong surface-enhanced Raman signals have been observed for pyridine species on these surfaces. This permits the direct comparison of pyridine spectra on different metal surfaces prepared by the same chemically clean method. The differences among the SER spectra of the aqueous pyridine species using different metals generally follow the trend of silver, cadmium, nickel, iron, gold, and copper, which can be explained by the selective formation of alpha-pyridyl species and the equilibria between end-on adsorbed pyridines and edge-on adsorbed alpha-pyridyl species on the different metal surfaces.

No abstract

No abstract

Electrical conductance (10"5 to 1 M) at 25, -15, and -30°and ultrasonic absorption (0.05-0.5 M) in the frequency range 5-330 MHz at 25, -15, and -30°have been measured for L1CIO4 in tetrahydrofuran (THF). The electrical conductance data reveal the presence of a minimum that can be interpreted and evaluated by the Fuoss-Kraus theory of triple ion formation (up to ~0.1 M). Numerical evaluation of ion pair and triple ion pair constants were made. The ultrasonic relaxation data are interpreted as due to the process of formation of triple ions, the barrier of activation energy for the process being comparable to the one for viscous flow.