This paper describes a way to perform diffuse reflectance measurements over the 1.0 to 3.0 µm spectral interval by using a Cary 171 spectrophotometer equipped with inexpensive standard accessory cell-space integrating spheres. The method involves coating the cell-space spheres with a powder of pure grade quenched sulfur and making a minor alteration in an electronic amplifier. A spectrum of ground gypsum crystal in the 2.6 to 3.0 µm spectral region and a spectrum of a layer of hectorite clay in the 1.0 to 3.0 µm spectral region are presented to illustrate the applicability of the above technique for making diffuse reflectance measurements in the near infrared.
