Refinement and thin film synthesis methods were used by members of six different institutions to design antireflection coatings for germanium substrates. The solutions are based on the use of zinc sulfide and germanium layers only. Several systems were found with an average reflectance that is less than 1% in the 7.7 to 12.3 microm spectral region.

There is increasing interest in the design of films with thicknesses on the order of 10 nm and less for a variety of applications, such as nanoparticles, plasmonics, quantum dots, solar reflectors, black mirrors, etc. The indices of refraction ( n and k ) for the effective media of such coatings depend on the materials with which such “layers” interface and the specific process parameters used to produce those films. The structures may typically be nucleating island structures and may also be continuous films. A key factor is that the n and k values vary in thickness until some thickness is obtained, usually > 20 n m . Heretofore, to the best of our knowledge, films have not taken into account thickness index variations during the design process. Software has now been developed where the index at a given thickness is computed at each iteration of the design optimization process. This allows more realistic design results utilizing the full representation of the behavior of the layers in question; the resulting coatings, when produced, are in better agreement with the designs. Including n and k versus wavelength and thickness in the design process is here referred to as double dispersion.

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Irradiation of KI in the fundamental edge results in a temperature dependent rate of F-center growth predominantly proportional to the inverse of the number of F-centers already produced. This is related to a new experimental resultthe quenching of low temperature luminescence in irradiatively colored crystals. In addition, the production of F-centers by absorption in perturbed exciton bands and the intrinsic production of u-centers are discussed.Bestrahlung von K J in der Bandkante fuhrt zu einer temperaturabhiingigen Verfiirbung des Kristalls durch F-Zentren. Die Bildung der F-Zentren verliiuft im wesentlichen umgekehrt proportional zu der Zahl der schon gebildeten F-Zentren. Dies ist verbunden mit einem neuen experimentellen Egebnisder Unterdruckung der Tieftemperatur-Lumineszenz in durch Strahlung verfiirbten Kristallen. AuBerdem wird die Bildung von F-Zentren durch Absorption in gestiirten Exzitonenbanden und die Bildung von u-Zentren diskutiert.

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