Direct energy transfer (DET) method conjunction with fast transient fluorescence (FTRF) technique were used to study small molecule desorption from a swelling poly(methyl methacrylate) (PMMA) glass in polymer solution, which is consist of naphthalene (N)-labeled PMMA chains in chlorofrom-heptane mixture. Desorption coefficients, D-d of pyrene (P) desorbing from the swelling PMMA glass prior to dissolution were measured and found to be 8.3 x 10(-8) and 1.3 x 10(-5) cm(2) s(-1) in short and long time regions, respectively. (c) 2005 Elsevier B.V. All rights reserved.