A system for monitoring infrared absorption of each of a plurality of materials contained in an array has an infrared transparent substrate for the array of materials. An infrared radiation source irradiates the materials in the array with infrared radiation. An infrared detection system monitors material absorption of the infrared radiation by the materials. A method of monitoring the infrared absorption spectrum of a library of materials includes synthesizing an array of material on a substrate. The materials are irradiated with infrared radiation and the absorption of the infrared radiation by the materials is monitored for each material.