Preparation of Q-state particles in Langmuir-Blodgett films

This review details the methods used in the production of a range of Q-state semiconductor and metal particles in Langmuir-Blodgett films, and describes some of the many methods used to characterise the particle-films. Chalcogenide based semiconductor particles can be grown in Langmuir-Blodgett films by cycles of immersion in a solution containing the appropriate metal cation and exposure to a chalcogenide gas. The preparation of metal chalcogenide (MX, where X = O, S, Se, Te) particles is discussed in terms of mechanistic insights into particle formation and growth. In particular, research investigating the role of the metal ion coordination sphere in the rate of particle formation and the roles of water and chemical capping in particle growth are presented. Various analytical techniques have been used to characterise the films including UV/visible absorption and grazing angle FTIR spectroscopies, atomic force microscopy, transmission electron microscopy, X-ray 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 photobleaching measurements, are discussed in light of their potential usage as components in photoactivated devices. (C) 2001 Elsevier Science B.V. All rights reserved.