Introduction to spectroscopy and types of spectroscopy
Spectroscopy is defined as it is a technique that uses the interaction of energy with a sample to perform an analysis.
What is a spectrum?
The data obtained by spectroscopy is called a spectrum . A spectrum is a plot of the intensity of the energy detected as a function of the wavelength (or mass or moment or frequency, etc.) of the energy.
What information is obtained from spectrum
A spectrum can be used for obtaining information on atomic and molecular energy levels, molecular geometries , chemical bonds , interactions of molecules and associated processes.
Spectra are used to identify the components of a sample (qualitative analysis). Spectra can also be used to measure the amount of material in a sample (quantitative analysis).
What instruments are needed?
Several instruments are used to perform spectroscopic analysis. In simple terms, spectroscopy requires an energy source (usually a laser, but it can be an ion source or a radiation source) and a device for measuring the variation of the source d energy (spectrophotometer or interferometer). .
What are some types of spectroscopy?
There are of many different types of spectroscopy as there are energy sources! Here are some examples:
The energy of celestial objects is used to analyze their chemical composition, density, pressure, temperature, magnetic fields, speed and other characteristics. There are many types of energy (spectroscopy) that can be used in astronomical spectroscopy.
Atomic Absorption Spectroscopy
The energy absorbed by the sample is used to assess its characteristics. Sometimes the energy absorbed releases light from the sample, which can be measured by a technique such as fluorescence spectroscopy.
Attenuated total reflectance spectroscopy
It is the study of substances in thin films or on surfaces.
An energy beam is passed through the sample one or more times and the reflected energy is analyzed. Attenuated total reflectance spectroscopy and the associated technique called frustrated multiple internal reflection spectroscopy are used to analyze coatings and opaque liquids.
Electronic paramagnetic spectroscopy
It is a microwave technique based on the separation of electronic energy fields in a magnetic field. It is used to determine the structures of samples containing unpaired electrons.
There are several types of electronic spectroscopy, all associated with measuring changes in electronic energy levels.
Fourier transform spectroscopy
It is a family of spectroscopic techniques in which the sample is irradiated by all relevant wavelengths simultaneously for a short period of time. The absorption spectrum is obtained by applying a mathematical analysis to the resulting energy diagram.
The Gamma radiation is the energy source in this type of spectroscopy, which includes activation analysis and Mossbauer spectroscopy.
The infrared absorption spectrum of a substance is sometimes called its molecular footprint. Although frequently used to identify materials, infrared spectroscopy can also be used to quantify the number of absorbent molecules.
Absorption spectroscopy, fluorescence spectroscopy, Raman spectroscopy and Raman enhanced surface spectroscopy commonly use laser light as an energy source. Laser spectroscopies provide information on the interaction of coherent light with matter. Laser spectroscopy generally has high resolution and sensitivity.
A mass spectrometer source produces ions. Information about a sample can be obtained by analyzing the dispersion of the ions as they interact with the sample, typically using the mass-to-charge ratio.
Multiplexed or frequency-modulated spectroscopy
It is the type of spectroscopy, in which each optical wavelength that is recorded is encoded with an audio frequency containing the original wavelength information. A wavelength analyzer can then reconstruct the original spectrum.
Raman scattering of light by molecules can be used to provide information about the chemical composition and molecular structure of a sample.
This technique involves the excitation of the internal electrons of the atoms, which can be seen as the absorption of X-rays. An emission spectrum of X-ray fluorescence can be produced when an electron falls from an energy state. higher in the gap created by the absorbed energy.
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