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Keywords:

  • Thin film;
  • Metal sulphide;
  • Photography;
  • Lead sulphide;
  • MSTF;
  • Photo-accelerated;
  • chemical deposition;
  • Solar irradiation

Abstract

Metal sulphide thin film (MSTF) photography based on photo-accelerated chemical deposition (PACD) of PbS thin films is described. Here an intensity distribution over the surface of a growing PbS thin film produces a thickness variation (0.06–0.15 μm) of the film which, when viewed under daylight, yields a specularly reflective image. Under 800 W m−2 of solar radiation a bluish MSTF photographic image (0.15 μm film thickness) on a coppery-bronze background (0.08 μm) is obtained in the PACD of PbS at the end of 25 min deposition when a high-contrast photographic negative is used as the object. The best contrast of 0.46 in the PbS MSTF photography in the reflection mode is obtained under the above condition of exposure when the optical transmission in a photographic negative in the image area is ∽30% and that in the background is ∽1%. The contrast available in the transmission mode in the MSTF photographic image is considerably less: ∽0.28 (maximum) for optical transmission of 1% and 100% in the background and image areas of the photographic negative respectively.