Quantitative evaluation of IR and corresponding VCD spectra
Thomas G Mayerhöfer1, Ankit K Singh2, Jer-Shing Huang2
1Leibniz Institute of Photonic Technology, Member of Leibniz Health Technologies, Member of the Leibniz Centre for Photonics in Infection Research (LPI), Albert‑Einstein‑Straße 9, 07745 Jena, Germany; Institute of Physical Chemistry (IPC) and Abbe Center of Photonics (ACP), Friedrich Schiller University Jena, Member of the Leibniz Centre for Photonics in Infection Research (LPI), Helmholtzweg 4, 07743 Jena, Germany.
Abstract:
Classical electromagnetic theory applied to infrared (IR) and vibrational circular dichroism (VCD) spectra of chiral compounds can provide useful insights, such as the fact that the area of all bands of wavenumber-normalized absorbance above zero must be the same as the area below zero. Additionally, dispersion analysis based on wave optics and dispersion theory, which was extended by Born and Kuhn to include chiral substances, can be used to quantitatively describe the dielectric function and the chiral admittance functions that shape IR and VCD spectra. For dispersion analysis, pairs of coupled oscillators, with five different kinds of parameters, namely oscillator strength, damping, oscillator position, vertical distance between coupled oscillators, and the coupling constant are used to model the dielectric functions and chiral admittance functions. We report the results of such an analysis for α-Pinene and Propylene oxide. For most bands, the oscillator model using two coupled oscillators is sufficient to achieve a good correspondence between experimental and modelled data.
Related Concept Videos
Infrared (IR) Spectroscopy: Overview
Different compounds display unique properties due to their...
IR Spectroscopy: Molecular Vibration Overview
Stretching vibrations are vibrational motions that occur along the bond line, changing the bond length or distance between two bonded atoms. They are further distinguished as symmetric or asymmetric. In symmetric stretching, the...
IR Spectroscopy: Hooke's Law Approximation of Molecular Vibration
According to Hooke's law, the vibrational frequency is directly proportional to...
Applications of IR Spectroscopy: Overview
IR Spectrum Peak Intensity: Amount of IR-Active Bonds
UV–Vis Spectroscopy: Woodward–Fieser Rules


