No abstract

A method is described for eliminating the undesirable effect of the double-layer capacity current on the sensitivity of a n A.C. polarograph. A square-wave voltage is used in place of the usual sinusoidal polarising voltage, and the amplitude of the A.C. component of the cell current is measured shortly before each sudden change in the applied voltage. Preliminary results suggest that the method is useful for the detection, at concentrations down to 2 x lo-' A:, of ions that are reversibly reduced,

Introduction: Many of the health problems

No abstract

The influence on the photocurrent of factors such as wavelength, scavenger concentration, ionic strength, diffusion coefficient of the hydrated electron, and the nature of products of the scavenging reaction, is considered. The discussion is illustrated by experimental data obtained by a variety of methods, and some preliminary results for substantially monochromatic light are described which lead to approximate relative rate constants for the scavenging of hydrated electrons by some simple inorganic ions and molecules. The presence of certain reducible solutes (1-3) in anThis current might be caused by: (a) homogeneous or inert electrolyte solution in contact with a uv irradi-heterogeneous photolysis (4) followed by reduction ated mercury electrode gives rise to a photocurrent at the electrode of one or more products of the photo-(ip) proportional at low concentration (Ca) to Cs 1/2. lytic reaction; (b) excited water molecules (5) that Vol. 113,No. 11 PHOTOCURRENTS