(i) Explain in detail spectroscopy. Write down its application.
Ans. Spectroscopy is the study of the interaction between matter and radiated energy. Historically, spectroscopy originated through the study of visible light dispersed according to its wavelength, by a prism. Later the concept was expanded greatly to comprise any interaction with radiative energy as a function of its wavelength or frequency. Spectroscopic data is often represented by a spectrum, a plot of the response of interest as a function of wavelength or frequency.
The instrument used to record the wavelength absorbed and the concentration of the absorbing species is called spectrophotometer.
Organic compounds absorb energy on interaction with electromagnetic radiations. As the electromagnetic radiations extend from high energy cosmic rays to low energy radio waves. The interaction of these different energy waves produces differnt types of changes in the matter. On this basis spectroscopy is classified in different types for example
The bond vibration and rotation of molecules need less energy in the IR region. That is studied in IR spectroscopy.
The electron excitation from low energy to high energy orbital need energy in the region of UV or visible. That is studied in UV/Vis spectroscopy
When low energy radio waves interact with molecule, they cause change the nuclear spin of some element like 1H1and 6C13.
These different spectroscopic studies are applied to determine the structure, functional group, physical and chemical properties of matter. For example
1. Mass spectrometry for determining the molecular weight, formula of organic compounds and identify the presence of isotopes.
2. Infra red spectroscopy to identify the functional group in organic compound , for structural investigation and bond energy.
3 NMR spectroscopy in the medical investigation for NMR investigation of molecules with fluxional structure. NMR studies of the chelate effect. The design and requirements of paramagnetic transition and lanthanide complexes for MRI signal enhancement.
In general A spectrum can be used to obtain information about atomic and molecular energy levels, molecular geometries, chemical bonds, interactions of molecules, and related processes. Often, spectra are used to identify the components of a sample (qualitative analysis). Spectra may also be used to measure the amount of material in a sample (quantitative analysis).