Spatial-frequency response of holographic gratings photodeposited from inorganic colloids.
Surface photodeposition is a photon-assisted process by which thin films are formed on substrates immersed in colloid solutions. We experimentally evaluate the resolution capabilities of the photodeposition process with amorphous selenium colloids by recording holographic gratings at different spatial frequencies, up to 2200 lines/mm. The experimental diffraction efficiencies are analyzed in terms of a theoretical model, which relates the spatial-frequency response to optical recording parameters and colloid particle sizes. The maximal experimental diffraction efficiency reaches 13% with a spatial frequency of f = 1100 lines/mm. The diffraction efficiencies decrease monotonically with spatial frequency, and drop to half of the maximal diffraction efficiency at f ≈ 1500 lines/mm. These resolution capabilities are achieved with colloid particle sizes extending up to 80 nm. The theoretical derivation indicates that to obtain spatial frequencies above 3000 lines/mm, one should restrict the colloid particle size to a(max) ≤ 30 nm.
Photodeposition of amorphous selenium films by the “selor” process I: Main features of the process, film structure
Abstract A new process—photodeposition from colloid sols—has been developed for the preparation of films, particularly films of amorphous selenium. The process has been labelled in our laboratory the Selor process. The growth of the films occurs under the influence of light. A difference has been observed between the film growth on opposite sides of the same transparent substrate immersed in the colloid solution: the film is of lower quality on the substrate side facing the light beam than on the opposite side. The latter film can be obtained in a highly homogeneous uniform state with an extremely smooth surface. Structure studies have revealed several stages of selenium layer formation. On those spots of the substrate that are covered with traces of certain foreign materials, non-compact structures appear. Investigation by means of X-ray diffraction, IR absorption spectra and Raman spectra has shown that the films obtained at temperatures not exceeding about 25 °C are completely amorphous and consist of a mixture of chain and ring molecular structures. One of the attractive features of Selor technology is the possibility of depositing patterned selenium films directly in a one-step process with high resolution.
The quantum particle in a box: what we can learn from classical electrodynamics
The problem of a charged particle enclosed in an infinite square potential well is analysed from the point of view of classical theory with the addition of the electromagnetic zero-point radiation field, with the aim to explore the extent to which such an analysis can contribute to enhance our understanding of the quantum behavior. First a proper treatment is made of the freely moving particle subject to the action of the radiation field, involving a frequency cutoff ωc. The jittering motion and the effective structure of the particle are sustained by the permanent action of the zero-point field. As a result, the particle interacts resonantly with the traveling field modes of frequency ωc in its proper frame of reference, which superpose to give rise to a modulated wave accompanying the particle. This is identified with the de Broglie wave, validating the choice of Compton’s frequency for ωc. For the stationary states of particles confined in the potential well, the Lorentz force produced by the accompanying field is shown to lead to discrete values for the mean speed and to an uneven probability distribution that echoes the corresponding quantum distribution. The relevance of the results obtained and the limitations of the classical approach used, are discussed in the context of present-day stochastic electrodynamics.