Copyright 2004 by Marcel Dekker, Inc. All Rights Reserved.

nanocrystals, where the diameter may only be a few lattice constants, this isno longer the case. Therefore, it becomes an issue how small one can push theeffective mass model before it breaks.C. The FutureClearly from the discussion in Section IV. B, important problems remain to besolved before a complete theoretical understanding about the electronicstructure in nanocrystals is obtained. However, hopefully, this chapter hasalso demonstrated that we are clearly on the correct path. Further, theoreticalissues are not the only area that needs attention. More experimental dataare also necessary. Although much work has been done, it is surprising thatafter a decade of work on high-quality nanocrystal samples, detailed spectroscopicstudies have only been performed on two compound semiconductors,CdSe and InAs. Hopefully, in the coming years, this list will beexpanded. Our understanding will be truly tested only by applying it to newmaterials.ACKNOWLEDGMENTSThe author gratefully acknowledges M. G. Bawendi, Al. L. Efros, C. B.Murray, and M. Nirmal, who have greatly contributed to the results anddescriptions described in this chapter.REFERENCES1. Pankove, J.I. Optical Processes in Semiconductors; New York: Dover, 1971;34 pp.2. Efros, Al.L.; Efros, A.L. Sov. Phys. Semicond. 1982, 16, 772.3. Ekimov, A.I.; Onushchenko, A.A. JETP Lett. 1982, 34, 345.4. Brus, L.E. J. Chem. Phys. 1983, 79, 5566.5. Ekimov, A.I.; Efros, Al.L.; Onushchenko, A.A. Solid State Commun. 1985, 56,921.6. Brus, L.E. J. Chem. Phys. 1984, 80, 4403.7. Murray, C.B.; Norris, D.J.; Bawendi, M.G. J. Am. Chem. Soc. 1993, 115, 8706.8. Norris, D.J.; Sacra, A.; Murray, C.B.; Bawendi, M.G. Phys. Rev. Lett. 1994,72, 2612.9. Norris, D.J.; Bawendi, M.G. Phys. Rev. B 1996, 53, 16,338.10. Nirmal, M.; Norris, D.J.; Kuno, M.; Bawendi, M.G.; Efros, Al.L.; Rosen, M.Phys. Rev. Lett. 1995, 75, 3728.Copyright 2004 by Marcel Dekker, Inc. All Rights Reserved.