Given common methods of preparing inlaid microdisk electrodes, shield thicknesses are often comparable to disk radii. Equations appropriate to characterizing the steady state, cyclic voltammetric response for microdisks embedded in in6nite insulating planes poorly approximate the steady state response at these electrodes because, on the time scale to achieve steady state, diffusion around the shield from behind the plane of the electrode contributions to the flux. A finite difference simulation with a nonuniform, expanding spatial grid is presented for reversible electrode kinetics over a range of scan rates s a c i e n t to follow the transition from linear to radial diffusion, including flux around the edge of the shield. The voltammetric response is influenced critically by shield thickness and electrode radius; a method is proposed and veritied experimentally to determine radius and shield thickness. The equations for infinitely thick insulators underestimate the current at a thinly shielded microdisk by 549%. Generation of a nonuniform, expanding grid is presented.Microelectrodes have become a major tool for studying nonstandard electrochemical systems. Solutions without added frozen solutions,6 and gas phase environments7-12 ' Present address: American Cyanamid,Dibble, T.; Bandyopadhyay, S.; Ghoroghchian, J.; Smith, J. J.; Sarfarazi, F.; (2) Cassidy, J.; Khoo, S. B.; Pons, S.; Fleischmann, M. J. Phys. Chem. 1985, (3) Bond, A M.; Lay, P. A.
Nanometer-sized ZnO crystals with the diameter from 20 nm to 110 nm were prepared by homogenous precipitation method (HPM). The photoluminescence (PL) spectra of as-prepared nanoparticles under excitation at the wavelength of 320 nm were detected. The PL spectra were fitted with Gaussian curves, in which a good fitting consisting of six Gaussian peaks was obtained. We observed that the multi-peak centers do not change much, while the relative amplitude of Gaussian combination to the band-to-band emission decreases rapidly with the increased grain size. It shows that the broadband emission at the lower energy is associated with the surface states.
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