  Time resolved intensity cross-correlation measurements of radiative cascades
are used for studying non-radiative relaxation processes of excited carriers
confined in semiconductor quantum dots. We spectrally identify indirect
radiative cascades which include intermediate phonon assisted relaxations. The
energy of the first photon reveals the multicarrier configuration prior to the
non-radiative relaxation, while the energy of the second photon reveals the
configuration after the relaxation. The intensity cross correlation
measurements thus provide quantitative measures of the non-radiative processes
and their selection rules. We construct a model which accurately describes the
experimental observations in terms of the electron-phonon and electron-hole
exchange interactions. Our measurements and model provide a new tool for
engineering relaxation processes in semiconductor nanostructures.
