A spherical quantum dot (QD) heterosystem CdS/SiO 2 has been studied. Each QD has a hydrogen-like impurity in its center. Besides that, it has been accounted that a polarization trap for electron exists at the interfaces due to the difference between the QD and matrix dielectric permittivity. It has been defined that for small QD radii there are surface electron states. For different radii, partial contributions of the surface states into the electron energy caused by the electron-ion and electron-polarization charges interaction have been defined. The linear light absorption coefficient of noninteracting QDs has been calculated taking into account the QD dispersion by the size. It is shown that the surface states can be observed into different ranges of an electromagnetic spectrum.

Abstract. The energy of interface states was obtained which is caused by the polarization charges at the interfaces. This energy was compared with the energy of electron internal states for CdS quantum dot sizes 1,2-2 nm. The interlevel absorption coefficient versus an electromagnetic wave frequency was defined.

The energy of quantum transitions of exciton-impurity states in a heterosystem with nanocrystals is calculated. The absorption spectra associated with the indicated transitions are analyzed. It is qualitatively shown that broad luminescence bands in the red region are related to the impurity acceptor states, and the high narrow ones in the violet region to pure excitonic states and excitonic states interacting with the ion of a donor. The satisfactory quantitative agreement of our calculations with experimental data for high energy luminescence bands is obtained.