We have extended the theoretical description of the lattice excitations in crystals formed of charged colloidal particle suspensions (CCPS) to include the effects of bounding surfaces. One of the new features that arises in a CCPS crystal confined by surfaces to form a film, is that propagating lattice waves cannot exist at the center of the Brillouin zone. Techniques have been developed to form systems of colloidal particles in monolayers on a water surface and on membranes. Transitions from gas to liquid to two dimensional solid phases have been observed in both classes of system. The two dimensional solid phases range from single crystals having a hexagonal lattice with long range translational order, to hexatic forms with short range translational order and long range orientation order, to amorphous or glass-like of /sub 2,6/lutidine + water have been extended to a film of thickness 0.5 .mu.m. The dynamical critical behavior of this film remains strictly three dimensional to within 2 mK of the extrapolated critical point, where an apparent first order transition occurs.

The First Binational USA-USSR Seminar-Symposium on the Theory of Light Scattering in Condensed Matter was held in Moscow 26-30 May 1975. The initial conception for a light scattering seminar of about fifty scientists - half from each side, including theorists and experimenters "well versed in theory" - arose from discussions between Professor J. L. Birman and Professor K. K. Rebane at the 1971 Paris International Conference on Light Scattering in Solids. This conception won approval among the active scientists on both sides. After considerable planning and some delays, it received both material support and encouragement from the appro priate organizations on each side: in the USA: The National Science Foundation (Division of International Programs), and the National Academy of Sciences; in the USSR: the Academy of Sciences USSR. A variety of reasons contributed to the positive response on both sides: for example, the considerable and high level of theoretical and experimental scientific activity on both sides in laser-related light scattering, optics, and generally - electro dynamics of condensed media - some along rather similiar lines; the impediments to free and easy communication and travel be tween USA and USSR scientists working on related problems; plus the desire to improve both contacts, and the free flow of informa tion and individuals, to the mutual advantage of both sides.

The Second USA-USSR Symposium on Light Scattering in Con densed Matter was held in New York City 21-25 May 1979. The present volume is the proceedings of that conference, and contains all manuscripts received prior to 1 August 1979, representing scientific contributions presented. A few manus cripts were not received, but for completeness the corresponding abstract is printed. No record was kept of the discussion, so that some of the flavor of the meeting is missing. This is par ticularly unfortunate in the case of some topics which were in a stage of rapid development and where the papers presented sti mulated much discussion - such as the sessions on spatial dis persion and resonance inelastic (Brillouin or Raman) scattering in crystals, enhanced Raman scattering from molecules on metal surfaces, and the onset of turbulence in fluids. The background and history of the US-USSR Seminar-Symposia on light scattering was given in the preface to the proceedings of the First Symposium held in Moscow May 1975, published as "Theory of Light Scattering in Condensed Matter" ed. B. Bendow, J. L. Birman, V. M. Agranovich (Plenum Press, N. Y. 1976). Strong scientific interest on both sides in continuing this series resulted in a plan for the second symposium to be held in New York in 1977. For a variety of reasons it was necessary to cancel the planned 1977 event, almost at the last minute.