Ultraviolet spectroscopy

Ultraviolet (electron) spectroscopy is a section of optical spectroscopy that includes the acquisition, investigation, and application of emission, absorption, and reflection spectra in the ultraviolet region .

The photon energy of the ultraviolet and visible spectral ranges is high enough (1.7-100 eV or from about 100 to 730 nm ) ^[1] to transfer the electrons of organic molecules from the ground state to the excited state - from binding to loosening orbitals . The energy difference between these states is quantized; therefore, molecules absorb photons only of a strictly defined energy.

In the UV region, all organic substances are absorbed. As a rule, the “working” region is in the range of 190–730 nm, mainly from 200 to 380 nm. In these areas, optical materials for the manufacture of prisms and cuvettes are transparent. Wavelengths less than 190 nm ( vacuum ultraviolet) are less convenient for operation, since the components of the air absorb oxygen and nitrogen in this area. Therefore, special vacuum chambers are used here to work, which complicates laboratory practice, but it is often indispensable, for example, in the study of dielectrics with a large band gap .

The amounts of substance required for the study are small - about 0.1 mg. In this regard, UV spectroscopy is one of the most common physicochemical methods for studying organic and inorganic compounds.