Abstract
The basic principle and applications of generalised two-dimensional (2D) near infrared (NIR) correlation spectroscopy are reviewed in this paper. A brief history and the basic principle of 2D correlation spectroscopy are described first, and then its importance for NIR spectroscopy is discussed. An outline of the mathematical treatment of generalised 2D correlation spectroscopy is given. Several examples of generalised 2D NIR and 2D NIR-mid IR (MIR) heterospectral correlation analysis are introduced.