Qualitative Experimental Study Research Articles

Study of polarization of laser radiation scattered 90 deg

A qualitative experimental study was undertaken of the effects of spherical particle scattering on the polarization of linearly polarized He-Ne laser beams. Four concentrations of particles (either 0.22- or 0.494-^im diam) were suspended in filtered, distilled water to serve as the scattering centers. Data representing the effects of volumetric particle concentration, detector acceptance angle, cylindrical scattering volume container diameter, and detector depth are investigated. In general, large diameter particles and high particle concentrations depolarize the incident beam the most. Also, increasing the length of the path traversed by the scattered beam greatly increases the depolarization of the beam.

Interdiffusion of gases in cylindrical mixing vessels

A qualitative experimental study has been carried out for the interdiffusion of bromine and air in a cylindrical mixing vessel. A time for complete mixing was derived from the appropriate integral form of Fick's equation, which may be compared to the Einstein equation for linear diffusion in an infinite vessel. Tabulated values for diffusion times in several gases emphasise the importance of allowing sufficient time for mixing prior to gas-phase kinetic studies.

Dislocations and Glide in Lead Sulfide as a Function of Deviations from Stoichiometry and Doping Additions

Point defects induced in PbS by slight deviations in chemical composition about the stoichiometric ratio were shown in a qualitative experimental study to affect dislocation density and strength. A very small but reproducible increase in dislocation density was observed by an etch-pit method in single crystals of PbS and in silver-doped PbS having excess sulfur or excess lead as compared with the stoichiometric composition. With a prismatic punching technique to obtain a measure of the yield strength, a slight increase in strength was found to correlate with an increase in point defect concentration in PbS. An etch-pit and slip-line analysis of glide in stoichiometric PbS verified the single primary glide system {100}〈110〉.