THE RADIATION OF HEAT FROM THE HUMAN BODY. IV. THE EMISSION, REFLECTION, AND TRANSMISSION OF INFRA-RED RADIATION BY THE HUMAN SKIN

Abstract

The distribution of energy in the emission spectrum of normal human skin corresponds with that which would be expected of a physical black-body radiator of the same temp. The reflectivity of the human skin, regardless of visible color, for infra-red radiation is very small, averaging less than 10% throughout the region from 2[mu] to 10[mu]. Layers of skin thicker than 1 mm. show no transmission to infra-red radiation and over 90% of the radiation is absorbed in the outer 02 mm. of skin. Transmission exps. on a very thin (0.05 mm.) skin reveal absorption bands which correspond to the infra-red frequencies of known molecular bands, viz., the C-H, O-H, and N-H linkages at wavelengths 3[mu] and 6[mu].