Light scattering in gold sols in relation to particle size and share

Summary

Previous work on gold solds with reference to the shape of the particle has been briefly recounted. Results of the measurements of the depolarisation of Tyndall scattering corresponding to the incident light being (a) unpolarised, (b) plane polarised with its electric vector perpendicular to the plane of observation, (c) plane polarised with its electric vector parallel to the plane of observation, have been reported. The values obtained and the observations made indicate that the particles in Farday’s sols are much smaller as compared with those in the other red sols prepared by using nuclear sols and hydrogen peroxide as the reducing agent; those in the blue sols are relatively the largest. In all the sols examined the shapes of the particles are far from being spherical. In general the size and the anisotropy of the particles appear to increase with the increase in the rate of growth brought about by enhancing the temperature during the preparation of the sol. The addition of potassium carbonate to the mixture before reduction seems to have the reverse effect.