Abstract

The mass-spectra of sulfur and selenium were measured at different vapors temperatures in order to determine their composition. In the mass-spectrum of sulfur measured at 70 eV electron energy and temperature of 380 K, both atomic and molecular ions S_n⁺ (n = 1-8) were revealed. The peaks of S₂⁺ and S₈⁺ molecular ions have the highest intensity, while the peak intensity of the S⁺ atomic ion is only 33.7% with respect to that of S₂⁺. As for selenium, in its mass-spectrum measured at 70 eV electron energy and temperature of 470 K, the Sе⁺ atomic ion and Sе₂⁺, Sе₃⁺, Sе₄⁺ molecular ions are present, among which the peak of Sе₂⁺ has the highest intensity.
The temperature dependences of atomic and molecular ions formation of sulfur and selenium have been studied in a wide range of temperature. The obtained temperature dependences are complex and they change significantly in relation to one another with temperature. It is explained with the change in bonds length between atoms within molecules with increasing temperature of vapors that can result in bond breaking, and, consequently, in altering the structure of molecules.
The energy dependences of the effective cross-section of sulfur and selenium atomic and molecular ions formation were measured in the energy region of 8-20 eV. The appearance energies of the ions were determined from the obtained energy dependences. It has been found that the energy dependences of the effective cross-section of ion formation have non-monotonic behavior due to the opening of new reaction channels with increasing electron impact energy. Features, in form of breaks and maxima, appeared in the energy dependences were also identified

Keywords: mass-spectrum, electron, atom, molecule, ion, ionization

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