Common types of spectroscopy Dr Gihan Gawish

1-Atomic Absorption Spectroscopy Energy absorbed by the sample is used to assess its characteristics. In analytical chemistry, atomic absorption spectroscopy is a technique for determining the concentration of a particular metal element in a sample Sometimes absorbed energy causes light to be released from the sample, which may be measured by a technique such as fluorescence spectroscopy. Dr Gihan Gawish

Atomic Absorption Spectroscopy Dr Gihan Gawish

2- visible Many atoms emit or absorb visible light. In order to obtain a fine line spectrum, the atoms must be in a gas phase. This means that the substance has to be vaporized. The spectrum is studied in absorption or emission. Visible absorption spectroscopy is often combined with UV absorption spectroscopy in UV/Vis spectroscopy. Dr Gihan Gawish

3- UV All atoms absorb in the Ultraviolet (UV) region. UV spectroscopy is also used in Quantifying protein DNA concentration The ratio of protein to DNA concentration in a solution. Dr Gihan Gawish

3- UV Several amino acids usually found in protein, such as tryptophan, absorbs light in the 280nm range and DNA absorbs light in the 260nm range. For this reason, the ratio of 260/280nm absorbance is a good general indicator of the relative purity of a solution in terms of these two macromolecules. Dr Gihan Gawish

4- Infrared It offers the possibility to measure different types of inter atomic bond vibrations at different frequencies. Especially in organic chemistry the analysis of IR absorption spectra shows what type of bonds are present in the sample. Dr Gihan Gawish

5- Fluorescence It uses higher energy photons to excite a sample, which will then emit lower energy photons. This technique has become popular for its biochemical and medical applications, and can be used for confocal microscopy, fluorescence resonance energy transfer, and fluorescence lifetime imaging. Dr Gihan Gawish

6- Raman When a beam of light passes through a sample, a small fraction of the light exits the sample at a different angle. If the wavelength of the scattered light is different than the original wavelength, it is called Raman scattering. Raman scattering of light by molecules may be used to provide information on: a sample's chemical composition molecular structure Dr Gihan Gawish

6- Laser Absorption spectroscopy, fluorescence spectroscopy, Raman spectroscopy, commonly use laser light as an energy source. Laser spectroscopies provide information about the interaction of coherent light with matter. Laser spectroscopy generally has high resolution and sensitivity. Dr Gihan Gawish

Electromagnetic spectroscopy Dr Gihan Gawish

Electromagnetic (EM) radiation (EM) radiation is a self-propagating wave in space or through matter. EM radiation has an electric and magnetic field component which oscillate in phase perpendicular to each other and to the direction of energy propagation. Dr Gihan Gawish

Source of energy depending on electromagnetic radiation Electromagnetic radiation is classified into types according to the frequency of the wave, these types include (in order of increasing frequency): radio waves, microwaves, infrared radiation, visible light, ultraviolet radiation, X-rays and gamma rays. Dr Gihan Gawish

The Visible Spectrum The visible spectrum (or sometimes called the optical spectrum) is the portion of the electromagnetic spectrum that is visible to (can be detected by) the human eye. Electromagnetic radiation in this range of wavelengths is called visible light or simply light. A typical human eye will respond to wavelengths in air from about 380 to 750 nm. Dr Gihan Gawish

Electromagnetic (EM) radiation Of these, radio waves have the longest wavelengths and Gamma rays have the shortest. A small window of frequencies, called visible spectrum or light, is sensed by the eye of various organisms, with variations of the limits of this narrow spectrum. EM radiation carries energy and momentum, which may be imparted when it interacts with matter. Dr Gihan Gawish

Dr Gihan Gawish