Electron Impact Induced Excitation Processes Involving the Sulfur Clusters S₂ to S₈

Abstract

Ionization efficiency curves of the gaseous sulfur species Si (i = 2–8) in equilibrium with solid red HgS were obtained by electron impact ionization. Analysis of fine structure of the curves yields energy levels of ground and excited ion states. — For S2 and S8 the experimental values are in good agreement with independent photoionization and photoelectron spectroscopic data from the literature. In the case of S3 to S7 numerous appearance potentials were determined which reflect processes such as direct ionization, autoionization, fragmentation, and predissociation. Extended Hückel calculations were performed for verification of the experimental energies and for spectroscopic assignment of states. — By the second and third law methods the heats of the gas phase reactions Si(g) = i/2 S2(g) (i = 3–8) and average bond energies of the sulfur species were determined.

Photoionization spectra and ionization energies of HSCl, HSSSH, SSCl, and HSSCl formed in the reaction system Cl/Cl2/H2S

“…Ionization of S n species was also achieved on electron impact ͑EI͒. 23 Rosinger et al detected HgS and S n (nϭ2 -8) after heating HgS to 430-490 K, 23 but the adiabatic IE determined in EI experiments are unreliable and appear to be too large.…”

“…Theoretical calculations indicate that S 3 has two forms, cyclic (D 3h ) and open (C 2v ), close in energy; therefore both forms may exist. 23 Zakrzewski and von Niessen calculated adiabatic IE for S 3 in various isomers at a configurationinteraction ͑CI͒ level with a basis set consisting of atomic natural orbitals ͑ANO͒. 24 Their results are not accurate enough for a reliable assignment of the electronic transitions.…”

Dissociative excitation and fragmentation of S8 by electron impact

“…By the conservation of energy, the range of kinetic energies for the fragments causes a corresponding spread in the threshold energies. 9,26,[34][35][36] The agreement between the different data sets can be seen in the review by Steudel et al 26 Using the Rau et al data 35 for example, we calculated the minimum energy required to produce at least one S atom with a residual molecular fragment S n consisting of n sulphur atoms. (iii) The various possible dissociative excitation processes in the energy interval considered each with a different threshold energy (see Table IV).…”

Inelastic Processes of Electron Interaction with Chalcogens in the Gaseous Phase (a Review)

“…For example, saturated sulfur vapor at 384 K contains S molecules (with = 2÷8), the fractions of which substantially change with the temperature [6]. Note that the experimental determination of the appearance energy for S + ions ( = 2÷8) at the interaction of sulfur with electrons was dealt with in works [7][8][9]. However, no comprehensive analysis of dissociative ionization channels was made in the cited works, first of all, because of the unknown composition and state of the neutral reaction products.…”