The near-infrared (NIR) (12,000-4000 cm−1) region of the electromagnetic spectrum, between the mid-infrared and visible, has often been viewed by spectroscopists to be of limited utility. This is unfortunate, and recently the use of the NIR has increased greatly, primarily for the quantitative analysis of food and agricultural products. However, many other areas of application of NIR spectroscopy remain unexamined. In this paper a novel use of NIR in the area of surface chemistry is demonstrated. Specifically, it is shown that NIR/Internal Reflection Spectroscopy (IRS) can be used to quantify surfactant adsorption reactions in situ.
J. J. Kellar, W. M. Cross, and J. D. Miller, "In Situ Near-Infrared Internal Reflection Spectroscopy for Surfactant Adsorption Reactions Using Reactive Internal Reflection Elements," Appl. Spectrosc. 44, 1508-1512 (1990)