Basic Theory of Molecular Spectroscopy
From the mid- 1950s, JASCO has been developing instruments and applications for some of the most important areas of molecular spectroscopy, including infra-red (FTIR), Raman, fluorescence, UV-visible/near infra-red, and chiral spectroscopy.
The evaluation of chirality is an important area in molecular spectroscopy because it is used in the development of biomolecules that are useful as new medicines, and for materials that can be used in novel technologies for applications in material science. Chiral spectroscopy includes diverse techniques such as optical rotation dispersion (ORD) and polarimetry, circular dichroism (CD) – both electronic and vibrational (VCD), as well as circularly polarized luminescence (CPL).
Circular dichroism spectroscopy (CD) is an essential analytical technique used to analyze chirality in molecules through their optical activity.
Vibrational circular dichroism (VCD) is a spectroscopy technique used to measure the absorption difference between left-handed and right-handed circularly polarized light in the infrared region. This is distinguished from electronic circular dichroism (ECD or CD), which focuses on the ultraviolet region.
UV-Visible/NIR spectroscopy can be divided into ultraviolet, visible, and near-infrared regions of the spectrum, depending on the wavelengths used. since its frequency is close to the overtone frequency of many natural vibrations, weak substance-specific absorption bands can be detected. It can therefore be used for non-destructive measurements, such as determining the sugar, lipid, protein content of foodstuffs and for identifying medicinals.
This technique offers a number of significant advantages over other spectroscopic or optical microscopy techniques, as it can be used for chemical or molecular analysis encompassing depth profiling and microscopic area mapping of samples with a spatial resolution of as little as 1 μm.
Fluorescence spectroscopy is routinely used for studying structural changes in conjugated systems, aromatic molecules, and rigid, planar compounds due to alterations in temperature, pH, ionic strength, solvent, and ligands.
Fourier-transform infrared spectroscopy is concerned with the vibration of molecules. Each functional group has its own discrete vibrational energy which can be used to identify a molecule through the combination of all of the functional groups.
FTIR is concerned with the vibration of molecules. Each functional group has its own discrete vibrational energy which can be used to identify a molecule through the combination of all of the functional groups. This makes FTIR microscopy ideal for sample ID, multilayer film characterization, and particle analysis.
The eBooks give a more in-depth look at the various molecular spectroscopy topics.
Download them here.