Nanosecond pulses of 10‐&mgr;m radiation can be generated by switching the output of a low‐pressure CO2laser with a N2‐laser‐controlled semiconductor reflection switch. These pulses have been used to injection mode lock the ∼50 J output of a 5‐liter TEA CO2oscillator. The 10‐&mgr;m reflectivity of the optically generated charge carriers is found to be a function of the wavelength of the switching laser, while 10‐&mgr;m transmission data has been used to monitor surface recombination before and after laser annealing of a germanium sample.