Mixtures of CF3Br and NO have been irradiated with a transversely excited atmospheric (TEA) CO2 laser under different experimental conditions. The isotopic composition of the undissociated CF3Br has been analyzed by mass spectrometry. C-13 enrichment factor in the remaining CF3Br and C-13 selectivity have been estimated and compared with those obtained with the pure substance and previous mixtures of CF3Br + X (X = He, Ar, Xe, H-2, D-2, N-2, CF4). The presence of NO produces a remarkable improvement of the enrichment factor. The trapping ability of NO, due to its radical-like character, improves drastically the results obtained previously.