Résumé
We present here studies of photoluminescence (PL) and time-resolved photoluminescence (TR-PL) of isolated single wall carbon nanotubes (SWNT) embedded in a gelatin matrix for temperatures between 10 and 300K. By this way the quality of the dispersion and the local environment of the SWNT are maintained. TR-PL experiments present a non-exponential temporal response due to the heterogeneity of the sample. The initial fast decay, temperature independent, is attribuated to small residual bundles which act as non radiative relaxation channels.The slow component shows a linear temperature dependence and is dominated by non-radiative processes for temperatures higher than 40 K. At low temperature, both the integrated PL intensity and lifetime measurements indicate the existence of a regime where carriers are trapped to shallow non-emitting states. From a quantitative phenomenological modelling we deduce an estimate of the dark/bright states splitting in SWNT. The PL experiments made on different types of SWNT (CoMoCAT, HiPCO...) lead to the valuation of the dark/bright states splitting for several chiralities and its diameter dependence.