The application of two‐dimensional correlation spectroscopy to surface and interfacial analysis

Abstract

Generalized two-dimensional correlation spectroscopy (2D COS) is a modern analytical tool that is increasingly being used in the interpretation of complex spectra that have broad, multiply overlapped spectral features. Besides functioning as a spectral resolution-enhancement tool similar to curvefitting or deconvolution, 2D COS possesses an additional advantage in that it is capable of discerning temporal relationships between intensity variations within a set of spectra. Infrared reflection-absorbance spectroscopy (IRRAS) at the air-water interface has been a very useful technique in studying the structure of biologically relevant molecules and the interaction between components of biological membranes in an environment close to what is found in nature. To better understand interfacial bio-mimetic structure, 2D COS can be applied to the IRRAS spectra to analyze changes in infrared intensities as a function of an environmental perturbation such as a change in temperature or surface pressure. To overcome some of the inherent limitations of the generalized 2D method, model-based approaches such as bn-and kn-correlation analyses and the global 2D phase angle method were developed. This review discusses some of the recent applications of these novel methods to Langmuir monolayers of phospholipids and proteins at the air-water interface and Langmuir-Blodgett polymer films.

2D-correlation analysis applied to in situ and operando Mössbauer spectroscopy

“…More details on this analytical method can be found here [74]. From our knowledge 2D-correlation spectroscopy analysis (2D-COSA) used for various experimental techniques (Infra-Red spectroscopy [75,76], Mass spectral data [77], Resonance light scattering [78], X-ray photoelectron spectroscopy [79]) have not yet used for Mössbauer spectroscopy. We present here an application of 2D-COSA for 57 Fe in situ Mössbauer spectroscopy during electrochemical extraction of lithium from LiFe 0.75 Mn 0.25 PO 4 with olivine structure.…”

Two‐dimensional correlation Raman spectroscopy for characterizing protein structure and dynamics

“…In 2006, Ozaki andŠašic [16] wrote a review on 2D correlation studies of biopolymers. Dluhy et al [17] and Jung and Noda [18] published reviews focused on technical aspects of the 2DCoS approach.…”

Synchronous–asynchronous two-dimensional correlation spectroscopy for the discrimination of adulterated milk

“…3 shows the normalized asynchronous 2D NIR correlation spectra of pure milk and milk adulterated with urea in the region of 4200-4800 cm À1 . Although asynchronous 2D correlations are more sensitive to differences in the form of the signal variation than synchronous correlations, [23][24][25] the asynchronous 2D NIR correlation spectral differences between adulterated milk with urea and pure milk are very subtle. These subtle differences may arise from spectral noise and baseline uctuations.…”