11 Type of Spectroscopy with Definition, Principle, Steps, Uses

Spectroscopy is the study of the interaction of matter and electromagnetic radiation to examine and identify substances based on their distinct spectral patterns. It entails determining how much light is absorbed by a chemical compound and at what intensity it goes through. They are determined by evaluating the radiant energy absorbed or emitted by the sample or object. Sir Isaac Newton was credited with the discovery of spectroscopy.

Type of Spectroscopy

The following section describes a few significant type of spectroscopy, along with their properties and uses.

Absorption Spectroscopy

It is a type of spectroscopy used for examining the relationship between electromagnetic energy and matter.

Principle: Determines how much of a given wavelength a sample absorbs.

Steps:

• Ensure that the sample is homogenous and contamination-free. (The sample may be in liquid, gas, or solid form.)
• Point a beam of radiation (such as UV, visible, or infrared light) at the sample.
• The radiation reacts with the sample, causing absorption.
• Determine the intensity of the transmitted radiation after it has passed through the sample.
• The absorbed energy corresponds to specified wavelengths, resulting in an absorption spectrum.
• Compare the transmitted and incident energy.
•  Quantify the amount of the substance present depending on the absorption intensity.

Uses: Examining molecular structures, identifying contaminants, and analyzing chemical composition.

Astronomical Spectroscopy

It is a type of spectroscopy that studies how the light interacts with astronomical objects.

Principle: Studies celestial objects by examining their emitted or absorbed light.
Steps:

• It involves passing incoming light from numerous stars via a telescope and into a spectroscope.
• As the light hits the spectroscope’s diffraction grating, it is separated into several wavelengths.
• The scattered wavelengths fall on photodetectors, which examine the nature of the wavelengths.
• The detectors create the spectrum’s flux scale based on wavelength by comparing measurements of reference stars.

Uses: Calculating the composition, temperature, and velocity of stars and galaxies.

Atomic Absorption Spectroscopy

It is a type of spectroscopy used for determining the concentration of certain components in a sample.

Principle: Determines the absorption of certain atomic transitions.
Steps:

• The liquid sample is combined with a certain volume of spirit, which is introduced to a flask and evaporated into a gas by a fuel-rich acetylene-nitrous oxide flame.
• A bulb with the appropriate wavelength is used as a light source.
• The gas created from the liquid sample is then passed through a detector, which measures the absorbance of the gas’s atoms.
• A similar procedure is used to detect the absorbance of solvent bank and standard solution.
• A graph is created that plots absorbance versus the concentration of molecules in the sample.

Uses: Quantifying trace metals in environmental samples and biological fluids.

Circular Dichroism Spectroscopy

It is a type of spectroscopy used for researching compounds’ structural characteristics, especially chiral molecules.

Principle: Examines variations in light that is circularly polarized to the left and right.
Steps:

• The sample is placed in a transport tank filled with buffers before being placed in the spectrometer.
• In the spectrometer, left and right circularly polarized light alternately pass through the sample.
• The photomultiplier detector in the spectrometer generates a voltage proportional to the circular dichroism (the difference in the absorption of left and right polarized light) of the resulting beam exiting from the sample.
• The sample’s circular dichroism is then compared to reference proteins to identify changes in secondary structure.

Uses: Researching the relationships and structures of proteins.

Fluorescence Spectroscopy

It is a type of spectroscopy used to investigate a sample’s light emission following photon absorption.

Principle: Detects fluorescence emission upon excitation.
Steps:

• Two samples with known and unknown quantities are collected in a transit vessel (cuvette).
• The containers are then placed one after the other in the spectrofluorometer, which is equipped with a light source and detectors.
• The spectrofluorometer is used to send light of a certain wavelength through a material.
• The photosensitive detectors in the spectrophotometer detect light flowing through the sample and transform it into digital numbers.
• A graph of fluorescence measured against sample concentration is created, which may subsequently be used to calculate the unknown sample concentration.

Uses: Chemical identification, biomolecular research, and medication development.

Mass Spectroscopy

It is a type of spectroscopy used for determining the mass and chemical composition of molecules.

Principle: Determines the mass-to-charge ratios of ions.
Steps:

• Combine 200 µl of the sample with 1.8 ml of 65% nitric acid.
• The mixture is then placed in a water bath at 50 degrees Celsius overnight.
• The tubes are then cooled to room temperature, and the sample is diluted with 8 ml of distilled water to achieve a nitric acid concentration of less than 20%.
• The sample is then loaded into the spectrometer and run.
• The results are produced by using computer software to generate a mass spectrum.

Uses: Identifying unknown chemicals, researching isotopes, and doing proteomics.

Nuclear Magnetic Resonance (NMR) Spectroscopy

It is a strong analytical type of spectroscopy that utilizes the magnetic resonance of the nucleus for determining the structure and characteristics of molecules.

Principle: Examines nuclear spin interactions.
Steps:

• The NMR instrument has been turned on and warmed up for 30 minutes.
• The NMR is configured with the required settings.
• Calibration is carried out by inserting an empty NMR tube to check that no background signals from the tube or the instrument are present.
• The sample is subsequently put in the NMR tube and the NMR spectrum is obtained.

Uses: Elucidating molecular structures, researching proteins, and designing drugs.

Raman Spectroscopy

It is an analytical technique for determining a compound’s chemical structure, polymorphism, crystallinity, and molecular interactions.

Principle: Scatters light to reveal vibrational modes.

Steps:

• Typically, aqueous solutions are utilized, and the needed laser is turned on after selecting the suitable wavelength.
• The spectrometer is then calibrated by utilizing a reference sample with the proper exposure energy and duration.
• The sample is then put under the microscope, with the focus on the layer to be analyzed.
• The monochromator scans a variety of wavenumbers, producing the Raman spectrum.
• The data is then examined using proper software, and an analysis is performed based on the peaks created on the spectrum.

Uses: Identifying chemicals, evaluating minerals, and examining biological tissues.

UV Spectroscopy

It is a type of spectroscopy used for studying the absorption of UV light by molecules.

Principle: Measures ultraviolet light absorption.
Steps:

• Two samples with known and unknown quantities are collected in a cuvette.
• The containers are then placed one after the other in the spectrophotometer, which is equipped with a light source and detectors.
• The spectrophotometer is used to pass light of a certain wavelength through the sample.
• The photosensitive detectors in the spectrophotometer detect light flowing through the sample and transform it into digital numbers.
• A graph of the absorbance measured against the concentration of the sample is created, which can subsequently be used to determine the unknown concentration of the sample.

Uses: Quantifying DNA, proteins, and aromatic chemicals.

X-ray photoelectron Spectroscopy

It is a type of spectroscopy used for determining the elemental composition and chemical state of a material’s surface.

Principle: Studies the interaction of X-rays with a sample’s surface.

Steps:

• Clean the sample surface to eliminate contamination.
• Use X-rays to illuminate the sample.
• Ejected electrons exhibit a distinct spectrum.
• Measure the energy and intensity of released electrons.
• Determine elemental composition and chemical state.

Uses: Examines core electrons to study material composition and bonding, providing information on surface qualities.

Atomic Emission Spectroscopy

It is a type of spectroscopy used for determining the elemental content of a material by measuring the wavelengths of light produced when the atoms are stimulated.

Principle: Analyzes emitted light wavelengths to identify specific elements based on their electronic transitions. 

Steps:

• Pour the sample into the device, usually in liquid or gas form.
• Convert the sample to free atoms, typically by a flame, plasma, or electrical discharge.
• Use heat or electricity to excite the atoms to higher energy levels.
• As excited atoms return to lower energy levels, they produce light with certain wavelengths.
• Use a photomultiplier tube or CCD detector to capture the emitted light.
• Using the wavelengths and intensities of the emitted light, determine the elemental composition and concentration of the sample.

Uses: Analyze the elemental composition of environmental, material, medicinal, and forensic materials.

In essence, Spectroscopy is a useful and important technique for both scientific inquiry and practical applications. Various type of spectroscopy investigate the interaction of light and matter, providing precise insights into the composition, structure, and characteristics of substances in various states of matter. Each type of spectroscopy—absorption, emission, fluorescence, infrared, NMR, or Raman—provides distinct benefits and procedures adapted to certain sorts of investigation. These type of spectroscopy have transformed areas like as chemistry, physics, biology, medicine, environmental research, and material science by allowing exact identification and measurement of elements and compounds.

Frequently Asked Questions (FAQ)

Related Articles

• Flora And Fauna
• Carbon Cycle