EMISSIVITY OF LIQUID GERMANIUM IN VISIBLE AND NEAR-INFRARED REGION

The normal emissivity of liquid germanium was determined from the dire ct measurement of the thermal radiation from the liquid surface and a blackbody, The monochromatic emissivity in the visible region and the average emissivity in the near infrared region were measured to invest igate the wavelength dependence, The emissivity of the liquid has litt le dependence on the wavelength and is 0.217+/-0.002 for the visible r egion (600-900 nm) and is 0.200+/-0.005 for the near infrared region a t the melting point. The emissivity has a weak dependence on the tempe rature from 910 to 1160 degrees C. The weak dependence agrees well wit h a dielectric response of the free electrons, (C) 1997 American Insti tute of Physics.