What is NIR spectroscopy?
Near-infrared spectroscopy, also known as NIR spectroscopy or NIRS, has been an established analytical technique for more than 30 years. It is a fast and reliable method to measure chemical and physical properties in solids and liquids. This first part of the series about near-infrared spectroscopy gives an introduction to how it works and presents the advantages and versatility of the technique.
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How does NIR spectroscopy work?
NIR spectroscopy analyzes the interaction between light and matter to generate a spectrum. In spectroscopic methods, light is typically not described by the applied energy, but by the wavelength. NIR spectroscopy operates in the near-infrared region of the electromagnetic spectrum, i.e., in the wavelength range of 780 to 2500 nm. In other words, a NIR spectrometer measures the absorption of light from the sample at different wavelengths in the NIR region. It must be noted that near-infrared is a different wavelength range than mid-infrared. The difference between these two techniques is explained in the blog article «NIR vs. IR: What is the difference?».
NIRS is a?secondary?technique. This means a prediction model needs to be created first. You can compare this, for example, to HPLC. If you want to identify or quantify a substance with HPLC, first you need to prepare standard solutions of the substance and measure them to create a calibration curve.