Spectroscopy – Fidar Shimi Jam

Atomic Absorption Spectrometry (AAS)

admin — Sun, 14 Mar 2021 12:45:14 +0000

Atomic absorption spectroscopy is an analytical method for measuring the amount of chemical elements in the form of free atoms in the gas phase as a function of the amount by which they absorb light. Its basic principle is simple: free metal ions absorb light of certain wavelengths. In analytical chemistry, AAS has many applications in determining the quantity of a specific element in a test sample. This technique is capable of detecting over 70 elements in a solution and in solid samples.

In practice, an absorption spectrum of the sample is used to measure the desired analyte. In order to correlate the degree of absorption with the analyte concentration, standards of known concentration are needed. For proper elemental analysis, the sample has to be transformed into free atoms first.

Currently, the most commonly used atomizers are electrothermal and flame atomizers. After atomization, the atoms are pumped with light, and the emissions are run through a monochromator, which isolates certain wavelengths before measuring them with a detector.

AAS has many applications in pharmaceutical manufacturing, water and wastewater analysis, toxicology research, biophysics, catalytic process studies, archaeology, and many other scientific fields.

UV–Vis Spectrophotometry

admin — Sun, 07 Mar 2021 12:51:41 +0000

A UV/Vis spectrophotometer is an analytical laboratory instrument that is used to study the interaction of light with matter in order to identify and measure chemical compounds. Its major function is to measure the light absorption by molecules so that it can precisely determine their concentration and structure. These systems have single-beam as well as double-beam designs. Visible-range spectrophotometers use tungsten lamps, and UV spectrophotometers use deuterium lamps to measure analyte concentration with a high level of accuracy.

Raman Spectroscopy

admin — Tue, 16 Feb 2021 13:09:59 +0000

Raman spectroscopy is a technique that is based on the scattering of light and has been widely applied in many branches of science. In chemistry, it is a powerful tool for determining the structure of molecules – Raman peaks are like a fingerprint for each compound. Although Raman and infrared spectroscopy have often been compared, the two methods differ significantly in their underlying theories and spectral behavior. They are often used in combination for more reliable structural analysis.

Raman spectroscopy has been particularly useful in the study of nanoparticles and in determining their properties. Applications include:

Identification and separation of organic and inorganic compounds and determination of chemical structure.
Defining boundary conditions for electric fields near surfaces.
Analyzing nanoparticles of some organic molecules and carbon nanotubes.
Determining the diameters of carbon structures and different inorganic nanoparticles.
Measuring carbon chirality (chirality is the situation in which a carbon atom is bonded to four different groups).
Characterizing Nanomaterials and Various Allotropes of Carbon

Inductively Coupled Plasma (ICP)

admin — Tue, 16 Feb 2021 13:01:00 +0000

Inductively Coupled Plasma spectroscopy is a very sensitive atomic spectroscopy method where atomization occurs in an extremely hot plasma field. Compared to other methods, it has better detection limits, higher repeatability, and a higher dynamic range. ICP is widely used for the elemental analysis of most elements, except argon, which is the inert gas used to form the plasma.
A plasma is a high-energy mixture of electrons and positively charged ions; although there are lots of charged particles in the plasma, the total of the electrical charges is close to neutral. Unlike flame-based techniques, ICP offers more complete atomization and has very low chemical interferences. The presence of a large number of free electrons in plasma also reduces the disturbance caused by ionization. There is also a significant benefit from atomization in a chemically inert environment, without analyte oxidation, which enhances signal stability and sensitivity. Problems common to spark, arc, or flame methods, such as self-absorption and self-reversal, are overcome to a large degree due to the uniform temperature distribution in the plasma. This uniformity provides a greater linear range of detection and improves the overall analytical performance.

Fourier Transform Infrared Spectroscopy (FT-IR)

admin — Tue, 16 Feb 2021 12:54:08 +0000

A Fourier Transform Infrared Spectrophotometer (FTIR) is a laboratory instrument that is used to obtain infrared absorption or emission spectra of solid, liquid, or gaseous materials. Unlike traditional dispersive spectrometers that scan one narrow wavelength band at a time, an FTIR instrument collects high-resolution data across a broad spectral range simultaneously – an enormous advantage in terms of speed as well as detail.
An FTIR spectrometer is most commonly employed for qualitative identification of chemical compounds, particularly organic materials and polymers, and determination of functional groups that are present in a sample of a compound. Thanks to its excellent spectral resolution and high repeatability, FTIR offers highly sensitive and reliable analytical performance.