The first FIRM-PL measurements in InSb/GaSb quantum dots have been performed. At low power densities the FIR absorption causes a transfer of carriers between dots and effectively cools the system, preferentially populating large, low energy dots and increasing the photoluminescence (PL) intensity, At higher powers the carrier temperature increases and the PL intensity falls. The spectral dependence of the FIRM-PL signal measures the energy spectrum of the quantum dots, showing a peak at 14.5 meV corresponding to transitions between the first two energy levels of the quantum dot distribution. (C) 2003 Elsevier B.V. All rights reserved.