The influence of intense infrared (IR) radiation in the range 7-17 μm on the photoluminescence (PL) of erbium in silicon has been investigated. To excite the PL a pulsed Nd:YAG laser operating in the visible with a wavelength of 532 nm has been used. The infrared beam was generated by a free-electron laser. In the experiment the intensity and decay kinetics of the low-temperature PL of Er-doped silicon were monitored as a function of the wavelength of the quenching beam and its delay with respect to the excitation pulse of the visible-light laser. The experiments show quenching of the PL by the IR pulse only at delays shorter than approximately 250 μs The result is interpreted as dissociation of the Er-related bound-exciton (BE) state whose effective lifetime is then estimated as approximately 100 μs. A special quenching feature for λ≈ 12.5 μm is detected indicating a possible "back-transfer" mechanism involving the excited Er state. For still longer delay times a small transient increase of Er PL is observed.