Transmission and reflection measurements in the infrared region between 340 and 40 cm-1 are presented for Irtrans 1–6. Measurements have been performed at room temperature and at liquid nitrogen and liquid helium temperatures.
J. J. Wijnbergen and A. A. Kelly, "Far Infrared Transmission and Reflection of Irtran 1 through Irtran 6 at Low Temperatures," Appl. Opt. 13, 2716-2718 (1974)