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A new type of solid state laser, tunable in the visible range, has been developed recently. Incorporation of perylimide and pyrromethene dyes into glasses prepared by the sol-gel method enables the design of new types of visible, stable solid lasers. These can be prepared either in the form of slabs or rods or as waveguiding active media deposited on glass or polymer supports. The difference between the refractive indices of the film and its support determines whether waveguiding occurs in the film or a leaky waveguide laser is formed. The efficiency of the lasers obtained recently is up to 70% when appropriate optical pumping is designed. We discuss the chemical and physical aspects of the photostability of the dyes in glasses, phenomena responsible for non-radiative relaxation of their excited state, and energy efficiencies of laser. [ABSTRACT FROM AUTHOR]

Cerium(III) energy levels and photophysics represent an intermediate status between d-group behavior and the other lanthanides showing narrow absorption bands and luminescence bands reminiscent of 4fq configuration atomic energy levels. Once the energetic separations of 0.5 to 2 eV of 5d-like orbitals are recognized to provide huge Stokes shifts and rather wide emission bands, it is also obvious that Ce(III) does not have a standard symmetry of ligating atoms (e.g. coordination number N = 9 and D3h know from aqua ions and anhydrous LnCl3 and LnBr3) but N is often 12, 11, 8, 7 or 6 (and rarely octahedral, as frequent in the d groups), 8 in irregular symmetries perhaps most typical. Scintillators for detecting very high kinetic energies (approaching the relativistic regime of photons and particles with very low rest-mass) involve closed shells, such as 4f and 5d in lutetium(III); barium 5p, 5d and 4f in highly electrovalent barium(II) in transparent crystals; and perhaps 4f and 6s in hafnium(IV) and tantalum(V) fluorides. [ABSTRACT FROM AUTHOR]

In the last few years the sol-gel process has turned into an interesting and promising method of synthesizing materials for obtaining thin or thick films with definite functions. The techniques of film preparation such as dip and spin coating are simple and allow us to prepare coatings with smooth optical surfaces with controlled stoichiometry, structure and texture. In this paper we give an up to date overview of what has been achieved in the field of chromogenic materials such as anodic or cathodic electrochromic coatings, counter or ion storage electrodes, transparent electron conductors and ionic conductors to be used in electrochromic (EC) devices. We also review the sol-gel research in the related areas of photochromic, thermochromic and electrooptic sol-gel materials whose properties are essentially used to modulate the luminous or solar energy as well as sol-gel materials prepared in the form of nanoparticles proposed recently for the development of a new type of solar cell. Finally we stress the future developments in these fast growing fields. [ABSTRACT FROM AUTHOR]

The field of nonlinear optics has been characterized by a remarkable increase in research activities during the past decade. We summarize the specific research into nonlinear optical materials prepared by the sol-gel technology. The chapter describes the preparation of glasses doped by semiconductor nanoparticles such as CdS, CuCl, CuBr, Bi2S3 and PbI2, metal nanoparticles and organic dyes. The third order susceptibilities of the various materials are tabulated. Glasses doped by organic dyes, their preparation, and properties of second and third order nonlinearity are discussed. The potential of these materials for industrial and technical applications is stressed. [ABSTRACT FROM AUTHOR]

We review the principles of optical and electrochemical sensors based on the use of the sol-gel technique, in particular their fabrication, working principles, and various configurations. We also report on potential applications, e.g. to environmental and clinical analysis, to gas sensing, and to bioprocess monitoring. Methods are critically reviewed for making such sensors, how to encapsulate organic, inorganic and biological matter, and how to control the properties of the resulting materials. Specifically, sensors for gases, ions, and organic as well as bioorganic molecules are discussed in some detail. [ABSTRACT FROM AUTHOR]

Over the last few years, considerable progress has been made with sol-gel coating films for optical and electronic applications. Nonlinear optical films and ferroelectric films are among those that have been studied most extensively. Optical and electronic coating films based on inorganic-organic hybrid or composite films have attracted much attention. These and other recent developments are stressed in this article which deals with a wide variety of optical and electronic coating films. [ABSTRACT FROM AUTHOR]