Theoretical Study On Potential Energy Function And Spectral Properties Of SCl~+ And SF~+ Molecular Ions

The molecular potential energy function has direct applications in many research fields such as atomic and molecular structure and molecular reaction dynamics.The molecular potential energy function can be used to derive information on the mechanical properties,spectral properties,and transition properties of molecules.Therefore,systematic research on molecular potential energy functions has very important theoretical significance and research value.Sulfur-containing molecules and radicals have attracted extensive attention from related scholars due to their significant importance in a wide variety of areas such as atmospheric chemistry,semiconductor industry,interfacial phenomena,organometallic and inorganic chemistry,etc.Among many diatomic systems containing sulfur elements,we find that SCI+and SF+are worthy of further in-depth study.Although our research group has used the single-reference method to predict the structure and related data of the electronic ground state of the two systems,the research is limited to the ground state,and the related information of the electronic excited state is still unknown.Therefore,the study of SCI+and SF+in this paper extends from the electronic ground state to the electronic excited state.Ap initio computations have been performed on SCI+ and SF+ using the icMRCI+Q method.The theoretical calculations on all A-S electronic states and corresponding ?states of the first and second dissociation limits of the two molecular ions have been carried out by adopting the all-electron relativistic augmented correlation consistent basis sets up to quintuple-? quality.With the help of least square fitting method,the potential energy curve of each electronic state is constructed and the spectral constant of each electronic state is determined.By solving the radial Schrodinger equation of nuclear motion,the vibration energy levels,inertial rotation constants and centrifugal distortion constants of all bound electronic states are calculated.In addition,this paper also analyzes the transition properties of SCl+ and SF+,such as transition dipole moment,Einstein coefficient,Frank-Condon factor and radiation lifetime.As far as the electronic ground state is concerned,the results of SCl+ and SF+ obtained in this paper have been greatly improved compared with the prediction results previously reported by our research group.The relevant information about the low-excited electronic states of the two systems is obtained for the first time.The feasibility of applying SCl+ and SF+ to laser cooling is also discussed in this article.The analysis results show that the two systems are not suitable for laser cooling.The simulated photoelectron spectrum of SCI+(X3?-)+e?SCl(X2?)and SF+(X3?-)+e ?SF(X2?)provide a reference basis for explaining the ionization process of SCI and SF molecules.In addition,the theoretical calculations on neutral SCI and SF molecules also have been carried out in order to verify the accuracy of SCl+ and SF+ related data obtained in this paper.The calculation method adopted is completely consistent with the calculation of SCl+ and SF+.The calculated results of SCl and SF are compared in detail with the spectral constants and vibrational energy levels reported in the literature.The consistency of the comparison results shows that the calculations of the SCl and SF molecules in this paper are accurate,and it also proves that the calculation results of the spectral constants,vibrational energy levels and transition properties of the ?-S and ?states of SCl+ and SF+ are reliable.It can provide references for further experimental and theoretical research on the two molecular ions.