Application Note

Getting the Best Results from NIR Measurements

Source: BaySpec Inc.

An NIR transmission spectrum of a polystyrene film. The narrow feature at 1160 nm is approximately 30 nm FWHM.

By Frederick G. Haibach, Bayspec

In chemistry, agriculture, and geology near infrared measurements (700-2500 nm) usually are made in transmission and reflection, and they are used to probe the molecular structure and composition of materials. Near infrared is preferred over mid-infrared when measurements need to be made at a distance, or with little or no sample preparation. The challenge is that the resulting spectra are difficult to interpret manually. Interpretation frequently is performed with the aid of multivariate analysis. This type of interpretation makes the choice of instrument characteristics less obvious but the physical and chemical fundamentals do not change. This application note details how optimal results with NIR spectrometers depend more on a good signal-to-noise ratio and less on high spectral resolution.