methods of spectral analysis
Spectral analysis is divided into several independent methods.Among them are: the infrared and ultraviolet spectroscopy, atomic absorption, luminescence and fluorescence analysis, reflection spectroscopy and Raman spectrophotometers, X-ray spectroscopy, as well as a number of other methods.
absorption spectral analysis based on the study of the absorption of electromagnetic radiation.Emission spectral analysis is performed on the emission spectra of atoms, molecules or ions, excited in different ways.
atomic-emission spectral analysis
Spectral analysis is often called the only atomic-emission spectral analysis, which is based on the study of the emission spectra of free atoms and ions in the gas phase.It is conducted in the wavelength range 150-800 nm.The radiation source is a sample of the
test substance is administered, then it evaporates and dissociation of molecules and ions formed excitement.They emit radiation, which is fixed by the registration device of the spectrometer.
Working with spectra
spectra of the samples are compared with the spectra of known elements, which can be found in the relevant tables of spectral lines.So find out the composition of the analyte.Quantitative analysis involves determining the concentration of the element in an analyte.It is recognized by the magnitude of the signal, for example, the degree of blackening or optical density of the lines on the plate, from the intensity of the light flux on the photoelectric receiver.
continuous emission spectrum gives substance, in solid or liquid form, and dense gases.This spectrum no discontinuities, it presents all wave lengths.Its character depends not only on the properties of individual atoms, but also on their interaction with each other.
emission line spectrum is characteristic of substances in the gaseous state, the atoms do not interact with each other.The fact that isolated atoms of chemical element emit waves strictly defined wavelength.
By increasing the density of the gas spectral lines begin to expand.To observe such a spectrum is used in the glow of a gas discharge tube or vapor substance in flames.If the white light to pass through nonradiating gas on the background of the continuous spectrum source appear dark lines of the absorption spectrum.Gas most intensively absorbs light of the wavelength it emits in the heated state.