SPECTROSCOPY

From Big Medical Encyclopedia

SPECTROSCOPY — the section of physics studying qualitative and quantitative structure of ranges of electromagnetic radiation. By methods C. investigate levels of energy of atoms, molecules and the macrosystems formed by them, and also possible transitions between levels of energy (see. Molecule ), what gives necessary information on a structure and properties of substance (its qualitative and quantitative structure, structure etc.). One of ranges of application of S. is spectral analysis (see), widely used in medicine.

Depending on the nature of the energy levels participating in formation of ranges distinguish electronic S. (visible and ultra-violet S.), oscillatory and rotary S. (infrared, combinational dispersion, microwave S. and radiospectroscopy), radiospectroscopy paramagnetic and nuclear magnetic resonance (see. Electronic paramagnetic resonance , Nuclear magnetic resonance ) and other types With, Depending on the nature of the studied object allocate atomic, molecular and electronic Page. Molecular spectrums can be investigated within almost all sections C. while the analysis of atomic ranges is included into preferential electronic S.

Sushchestvenno's tasks possibilities of the spectroscopic equipment in connection with creation of lasers extended (see. Laser ). Methods C. of resonant combinational dispersion and optical Doppler are developed by Page. In particular, by means of opticheskoy.doplerovsky S.'s method perhaps continuous overseeing by movement of molecules, macromolecules, cytoplasmatic structures in living cells, and also studying of effect of medicinal and other substances on a cell etc.

S. is carried out by means of various spectral devices. They are classified by various signs: to a way of dispersion (decomposition) of light, method of registration of a range, working space (range) of a range, etc.

On a way of dispersion of electromagnetic radiation on monochromatic components and their subsequent registration distinguish prismatic spectral devices (are based on dependence of index of refraction of material of a prism on wavelength) and the diffraction spectral devices using dependence of an angle of diffraction of light on wavelength (see. Optics ).

By a method of registration spectral devices divide into spectroscopes (registration of a range is carried out visually), spectrographs (ranges it is recorded on a photoemulsion), spectrometers (register absolute intensity of ranges) and spectrophotometers (register absorption spectrums as a percentage of a transmission or units of optical density), quantometers, or polychromators — the devices with photo-electric registration used for carrying out the bystry issue analysis of connections.

Depending on a measuring range spectral devices divide into spectrometers and spectrographs for the UF short-wave area (range of 10 — 200 nanometers); spectrographs, spectrometers and spectrophotometers for U F and a visible part of a range (200 — 760 nanometers); spegtrometra and spectrophotometers for near infrared (2 — 50 microns) and a distant infrared spectral range (50 — 1000 microns).

Rather independent area C. is studying of absorption spectrums of electromagnetic energy in micro and radio frequency ranges of lengths of waves the particles (atoms, molecules, ions) having in magnetic moment (see. Electronic paramagnetic resonance , Nuclear magnetic resonance ).

A number of peculiar hybrid spectral techniques, such, in particular, as photoacoustic S., at a cut the sample is irradiated with light (in ultra-violet, visible or near infrared areas) modulated by acoustical frequency is widely used. In the course of nonradiative transition of system to a ground state there are fluctuations of pressure in the gaseous fluid surrounding a sample caught by the microphone as acoustic signals.

Page — a universal method qualitative and quantification of composition of substance, studying of its structure, properties and other parameters. Atomic S.'s methods allow to define the elements which are a part of substance, in particular the maintenance of these or those ions in serum, urine and others biol. liquids (issue and atomic and absorbing spectral analysis). Molecular S. is used for the purpose of identification of substances, quantification (determination of content in test of enzymes, vitamins, hormones, proteins, nucleinic to - t, carbohydrates. lipids, ions and so forth), studying of kinetics of chemical and biochemical reactions.

By means of methods of nuclear magnetic resonance and infrared S. definition of a structure of organic molecules, their spatial structure, mechanisms and kinetics of biochemical reactions is carried out. By method of an electronic paramagnetic resonance reveal intermediate free radical products, study the mechanism of damage biol. fabrics (see. Radicals free ) etc. By means of gamma-resonant S. study structural transfomations of ferriferous proteins, in particular at a disease of blood of the person. Photoacoustic S.'s method is used for studying of the samples which are strongly scattering light, including intact biol. material (cellular organellas, cells, fabrics and bodies).

See also Optical techniques of a research , Spektrofotometriya .



Bibliography: L. A mushrooms. Introduction to molecular spectroscopy, M., 1976; Zaydel A. N., Ostrovskaya G. V. and Ostrovsky of Yu. I. Tekhnik and practician of spectroscopy, M., 1976; Landsberg G. S. Optics. M, 1976; Slavin U. Atomic absorption spectroscopy, the lane with English, L., 1975, bibliogr.; Frayfelder D. Physical biochemistry, the lane with English, page 383, M., 1980.


R. R. Lidemang.

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