4.12 Infrared radiation detection For a nonideal body, the intensity distribution must be multiplied by the emissivity a. the wavelength of peak intensity is given by the Wien's displacement law 2898/T (4.132)❑ 4.12 Infrared radiation detection For a nonideal body, the intensity distribution must be multiplied by the emissivity,  . The wavelength of peak intensity is given by the Wien’s displacement law:  2898/T (m) max = （4.132）