Photocurrents Produced by Ultraviolet Irradiation of Mercury Electrodes

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

Photoinduced Electrochemical Reduction of Nitrite at an Electrochemically Roughened Silver Surface

“…The concept was postulated as early as 1965 by Barker et al who proved that at certain electrode potentials and photon energies the observed photocurrent arises from photoelectron emission from the metal into the electrolyte solution. 16 Prior to his work, Berg attributed experimentally observed photocurrent at a mercury electrode to the absorption of light by the metal and production of "hot electrons" causing an increase of the electron transfer rate to the solute in the solution. 17 Heyrovsky invoked the concept of photodecomposition of surface charge transfer complexes formed between a metal and a solvent or solute.…”

Studies on Photo-polarography. IV. Solvent Effect on Photocurrents

“…At a given potential the photocurrent was proportional to the square root of the nitrate concentration (0.1-10 mm) in good accordance with Barker's theory. 1) According to the Barker model of the process, the photoelectrically emitted electrons are ther-(image force) is in balance with the thermal energy of the electron, i.e., (1) ( 2) where K1 and K2 are the constants.…”

General Threshold Theory of Electronic Emission from the Surface of a Metal

“…The last statement means, that in the region z < 0 the quantity lvfl remains approximately constant when Ef changes in the considered threshold energy interval AE. This constancy evidently takes place also at the point z = 0, and it follows then, that Iyi!z=o = const being approximately independent of p. The last equality is t o be used as an appropriate boundary condition for equation (3).…”