We have used the FELIX infrared free-electron laser (FEL) at the FOM Institute for Plasma Physics in The Netherlands to enrich silicon isotopes by multiple-photon dissociation of the molecule Si2F6. The absorption of infrared radiation induces the reaction Si2F6 --> SiF4 + SiF2. Much of the SiF2 product further reacts to form additional SiF4. The Si2F6 molecule has absorption bands in the 10, 12, and 25 mu m spectral regions. FEL-induced reactions occurred in all three regions. The reaction fraction was highest for the stronger band in the 10 mu m region. Reactions in all three bands were isotopically selective. Irradiation in the 10 mu m region at 952 cm(-1) gave an isotopic selectivity of 5.6 for Si-30. For comparison, the published isotopic selectivity using a CO2 laser in the same spectral region is in excess of 17. Wi: attribute the lower selectivity obtained with an FEL to its longer macropulse, its broader spectral width, and differences in experimental procedure. FEL irradiation in the region of the 12 mu m band produced isotopic selectivities in excess of 20 for Si-30. Selective production of Si-28 was high in the 25 mu m region. We used changes in the infrared spectra of the irradiated samples for all analyses of reaction and isotope enrichment except for a single confirmation of enrichment with a mass spectrometer.