Preparation of Q-state particles in Langmuir-Blodgett films

This review details the methods used in the production of a range of Q-stat e semiconductor and metal particles in Langmuir-Blodgett films, and describ es some of the many methods used to characterise the particle-films. Chalco genide based semiconductor particles can be grown in Langmuir-Blodgett film s by cycles of immersion in a solution containing the appropriate metal cat ion and exposure to a chalcogenide gas. The preparation of metal chalcogeni de (MX, where X = O, S, Se, Te) particles is discussed in terms of mechanis tic insights into particle formation and growth. In particular, research in vestigating the role of the metal ion coordination sphere in the rate of pa rticle formation and the roles of water and chemical capping in particle gr owth are presented. Various analytical techniques have been used to charact erise the films including UV/visible absorption and grazing angle FTIR spec troscopies, atomic force microscopy, transmission electron microscopy, X-ra y photoelectron spectroscopy, surface plasmon resonance and quartz crystal microbalance gravimetry. Methods for manipulating the optical properties of the particle-films, such as the production of core-shell particles and co- existent particles of different composition are presented. The formation of Q-state metal particles by CO or hydrazine reduction is referred to as an analogous technique. Finally, the results of photoelectrochemical and photo bleaching measurements, are discussed in light of their potential usage as components in photoactivated devices. (C) 2001 Elsevier Science B.V. All ri ghts reserved.