Dynamics of spontaneous growth of light-induced sodium droplets from the vapour phase

Spontaneous growth of light-induced sodium clusters from the vapour phase u p to macroscopic droplets of radii of about 140 nm has been studied. The in tensity of light scattered during the droplet growth is compared with the p rediction of Mie theory in which it is assumed that the droplet radii can b e described by a single size at any stage of the growth process or by a dis persion of sizes. The damping rate of electron movement in a sodium droplet ( gammah = 1 eV +/- 15%) is determined from the assumption of the Drude di electric function as the external parameter of Mie theory. The radius and t he relative concentration of clusters at successive stages of the growth pr ocess were determined. The experimental scattering data were also compared with the model assuming the existence of a dispersion of cluster size, whic h was allowed to be a nonsymmetric function of sizes. The distribution of c luster sizes was found to be broadened towards larger droplets. The experim ental results of our study are confronted with the expectations from classi cal nucleation theory.