EXCHANGE INTERACTION AND PHONON CONFINEMENT IN CDSE QUANTUM DOTS

The fine structure of the lowest (1S(3/2), 1s(e)) electron-hole pair s tate has been studied for CdSe quantum dots embedded in glass and with sizes R<a(B). Besides the very narrow peaks from the exchange-split l owest pair states (full width at half maximum of 2 meV), two additiona l structures have been found in luminescence and assigned to confined acoustic photons. The observation of discrete acoustic phonons in the emission spectra verifies the importance of low-frequency acoustic pho nons for energy relaxation in quantum dots. The size dependence of the different peaks has been determined and compared with theoretical mod els.