TiO 2 doped with Cu 2+ initiates the formation of brookite phase along with anatase. Doping of Cu 2+ introduces structural defects into TiO 2 . The direct evidence is the low intense and broad diffraction peaks. Raman peaks of doped TiO 2 are also broad and are blueshifted. Pure TiO 2 exhibits an absorption in the UV region, the position of which is shifted towards the visible region on incorporation of Cu into it. The visible absorption peaks arise due to the

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An annular pupil, which can be used to produce a Bessel beam, when combined with radially polarized illumination promises improvements in microscope resolution, increased packing density for optical storage, and finer optical lithography. When combined with a circular detection pupil in confocal microscopy a point-spread function 112 nm wide results (lambda = 488 nm). Radially polarized annular illumination of a solid-immersion lens can yield a focal spot smaller than 100 nm for lambda = 488 nm. Use of radially polarized illumination with pupil masks is discussed.