Two-Dimensional Correlation Spectroscopy (2DCOS)
Two-dimensional correlation spectroscopy (2DCOS) has been used as an analytical method to study changes induced by external perturbations such as temperature, surface reactions, pH, and adsorbate concentrations. In typical one-dimensional spectroscopic experiments, an electromagnetic probe is used to investigate interactions of the probe and system. However, once an external perturbation is used to stimulate the system, spectral intensity changes can occur. 2DCOS is a way of aggregating spectra to establish whether intensity fluctuations are correlated and to determine the sequential sequence of peak changes
2DCOS can be considered a quantitative intensity comparison of two spectra between some perturbation interval. This is a way to visualize similarity or dissimilarity of the correlations between intensity fluctuations. Importantly, recent 2DCOS experiments have been used along with IR spectroscopy to investigate different NP surface interactions such as oxyanion adsorption, protein conformational change, and displacement reactions.