Many-body effects in the optical properties of quasi-two dimensional systems

Abstract

The importance of many-body effects in two and quasi-two dimensional 1 systems has been studied for many years In such contexts as electrons in the inversion layer at semiconductor-oxide interfaces and electron layers deposited on the surface of liquid helium. For the quasi-two dimensional electron gas as found in inversion layers, attention has focused on electron-electron interaction with regard to its influence 2 on band energy levels , longitudinal and transverse dielectric functions 3, inter-subband optical absorption 4 and exciton effects 5 Dahl and Sham 6 and Equiluz and Maradudin 7 have studied carefully the question of optical reflectance from an inversion layer, taking fully into account depolarization effects whose importance in shifting the optical absorption energy was stressed earlier. 8 In the present work, we wish to focus attention on a different quasi-two dimensional system, viz., that of chemisorbed atoms on a metal surface. The object of our interest is the role of many body effects in the optical properties of such a system. As we shall see, there are important similarities and differences between this system and that of an inversion layer.