The gas-phase chemiionization reaction between samarium and oxygen atoms: A theoretical study

Abstract

The SmϩO chemiionization reaction has been investigated theoretically using a method that allows for correlation and relativistic effects. Potential energy curves have been calculated for several electronic states of SmO and SmO ϩ . Comparison with available spectroscopic and thermodynamic values for these species is reported and a mechanism for the chemiionization reaction SmϩO is proposed. The importance of spin-orbit coupling in the excited states of SmO, in allowing this chemiionization reaction to take place, has been revealed by these calculations. This paper shows the metal-plus-oxidant chemiionization reaction.

Electronic structure of SmO and SmO− via slow photoelectron velocity-map imaging spectroscopy and spin-orbit CASPT2 calculations

“…The literature is in agreement regarding the preferred septet spin state and 4f 5 6s 1 configuration of SmO. [11][12][13]15,[17][18][19]40 Higher-lying states involve excitations TABLE I. Theoretical SO-CASPT2 and experimental cryo-SEVI energies of low-lying states of neutral SmO from this work, compared to state assignments and experimental fluorescence measurements from the work of Linton and co-workers.…”

“…In much of the spectroscopic literature on SmO, [11][12][13]18 the electronic states are labeled with an (N)Ω convention, which represents the Nth state with a value of Ω for the projection of the total electronic angular momentum onto the internuclear axis. As has been discussed by Paulovič et al, 19 a definitive assignment of the Ω value cannot be made for the lowestenergy CASPT2 states due to the very small energy separations between the states with respect to the resolution of the method. Fortuitously, the X(0 ) ground state of SmO identified by Linton and co-workers [11][12][13] is an Ω = 0 state; the lowest-energy SO-CASPT2 state reported here (Table I) is singly degenerate and therefore consistent with this assignment.…”

“…[16][17][18] More recently, Paulovič et al calculated the potential energy curves of SmO at the CASPT2 level, identifying several hundred spin-orbit (SO) states arising from the ground septet states alone. 19 Here we seek to improve on previous work via a joint experimental and theoretical investigation of the spectroscopy and electronic structure of SmO, using slow photoelectron velocity-map imaging (VMI) spectroscopy of cryogenically cooled SmO anions (cryo-SEVI), a high-resolution variant of anion photoelectron spectroscopy, alongside high-level spinorbit (SO) complete active space calculations with corrections from second order perturbation theory (CASPT2). The inherent high resolution of the SEVI technique in combination with the spectral clarity afforded by cold ions reveals detailed spectral information.…”

The chemiionization reactions Ce + O and Ce + O2: Assignment of the observed chemielectron bands

“…Spin‐orbit coupling effects were computed using the complete active space state interaction (CASSI) method 10, 11, in which an effective one‐electron spin‐orbit Hamiltonian, based on the atomic mean field approximation of the two‐electron part, was employed. This approach has been shown to work successfully in a number of earlier applications 12–23. All calculations were performed using the MOLCAS 7.0 program package 24.…”

A theoretical study of the gas-phase chemi-ionization reaction between uranium and oxygen atoms

“…This work follows on from our study on the Sm+ O chemi-ionization reaction, which was the first theoretical study of a metal-plus-oxidant chemi-ionization. 9 The following section presents the Computational Details. The calculated results along with the available experimental values are given in Sec.…”