Breakthrough Potential in Near-Infrared Spectroscopy: Spectra Simulation. A Review of Recent Developments

Abstract

Near-infrared (12,500–4,000 cm −1 ; 800–2,500 nm) spectroscopy is the hallmark for one of the most rapidly advancing analytical techniques over the last few decades. Although it is mainly recognized as an analytical tool, near-infrared spectroscopy has also contributed significantly to physical chemistry, e.g., by delivering invaluable data on the anharmonic nature of molecular vibrations or peculiarities of intermolecular interactions. In all these contexts, a major barrier in the form of an intrinsic complexity of near-infrared spectra has been encountered. A large number of overlapping vibrational contributions influenced by anharmonic effects create complex patterns of spectral dependencies, in many cases hindering our comprehension of near-infrared spectra. Quantum mechanical calculations commonly serve as a major support to infrared and Raman studies; conversely, near-infrared spectroscopy has long been hindered in this regard due to practical limitations. Advances in anharmonic theories in hyphenation with ever-growing computer technology have enabled feasible theoretical near-infrared spectroscopy in recent times. Accordingly, a growing number of quantum mechanical investigations aimed at near-infrared region has been witnessed. The present review article summarizes these most recent accomplishments in the emerging field. Applications of generalized approaches, such as vibrational self-consistent field and vibrational second order perturbation theories as well as their derivatives, and dense grid-based studies of vibrational potential, are overviewed. Basic and applied studies are discussed, with special attention paid to the ones which aim at improving analytical spectroscopy. A remarkable potential arises from the growing applicability of anharmonic computations to solving the problems which arise in both basic and analytical near-infrared spectroscopy. This review highlights an increased value of quantum mechanical calculations to near-infrared spectroscopy in relation to other kinds of vibrational spectroscopy.

Near-Infrared Spectroscopy as a Rapid Screening Method for the Determination of Total Anthocyanin Content in Sambucus Fructus

“…Simulation of NIR spectra using the tools of theoretical chemistry has become feasible in recent years [ 38 ]. With aim to interpret the features of the PLSR models established in this study, we performed quantum chemical calculation of the NIR spectra of the three anthocyanins.…”

“…Quantum mechanical calculations were carried out with Gaussian 09 Rev.E.03 Software (Gaussian, Inc., Wallingford, CT, USA) [ 37 ]. The quantum mechanical study yielded band assignments for the first overtones and binary combination bands, which form the most meaningful contribution to NIR spectra [ 38 ].…”

The Sample, the Spectra and the Maths—The Critical Pillars in the Development of Robust and Sound Applications of Vibrational Spectroscopy

“…Very few scientist are aware that black box technology can be expanded for the physical-chemical characterisation of spectra [51][52][53]. Please note that it is not the objective of this paper to provide a comprehensive and detailed description of the different vibrational methods used as rapid or high throughput methods [54][55][56][57][58][59][60][61][62][63][64]. More detailed information about the different methods and techniques available as well the different technical characteristics or properties of the commercial instrumentation available in the market can be found elsewhere [54][55][56][57][58][59][60][61][62][63][64].…”

Historical Evolution and Food Control Achievements of Near Infrared Spectroscopy, Electronic Nose, and Electronic Tongue—Critical Overview

“…From an analytical standpoint, the quality of the obtained results is dictated by the variability induced by environmental conditions and the efficiency of compensating their resulting errors. The complexity of NIR spectra is another inevitable challenge [ 20 ] that demands a mastering of chemometric tools to understand any correlative relation between the generated spectra and the peculiarities of the studied samples.…”

“…The versatility in the design of NIR spectrometers has been further extended through gradual improvements aimed at enhancing the functionality of NIR spectroscopy resulting in a plethora of instruments [ 20 ]. The most recent and most significant achievement of NIR spectroscopy was the miniaturization, which undoubtedly resulted in the disentanglement of the technology [ 46 ].…”