Vibrational analysis of the ³Π₁–X¹Σ⁺ band systems of SiCl⁺

Abstract

The emission spectrum of the SiCI+ radical cation, excited by the thermal energy He+ + SiCI, reaction, has been observed and vibrationally analyzed in the 310-350nm region. The two new subband systems, ci3II0+-XIZ+ and 03n,-XIZ+, have been identified.The vibrational assignments were confirmed by the observed isotope band heads of Si35CI+ and Si37CI+. The following molecular constants (in c m l ) have been obtained for the X I Z + , a3110+, and ci311, states. c i 3 n , : T , = 3 1 8 3 6 f 3 ; 0 , = 5 9 6 . 0 f 1 . 8 ; o C x , = 6 . 7 5 f 0 . 5 6 a3n0+: T , = 31 721 + 2 ; o , = 595.8 + l.o:o,s, = 6.62 * 0.12 XIZ+: o, = 680.8 k 0.6; o,x, = 2.57 zk 0.05 -Le spectre d'emission du radical libre charge positivement SiCI+, excite par la reaction d'energie thermique He+ + SiCI, a eteobserve et a fait I'objet d'une analyse vibrationnelle dans la region 310-350nm. On a identifie deux nouveaux systemes de sous-bandes, a3no+-XIZ+ et a3n,-XIZ+.Les assignations vibrationnelles ont ete confirmees par les observations relatives aux differences isotopiques entre les tstes de bandes de Si3SCI+ et SP7C1+. On a obtenu, pour les etats X I Z + , a 3 n o + et a3111, les valeurs suivantes des constantes moleculaires, en cm -I . a 3 n , : T,= 31 836 f 3 ; o , = 596.0 f 1,8;o,x, = 6.75 f 0.56 a3110+: T , = 31 721 + 2; o, = 595,8 f 1.0; o,x, = 6.62 + 0.12 XIZ+: o, = 680.8 f 0.6; o,x, = 2,57 + 0.05 [Traduit par le journal] Can. J . Phys.. 59.985 (1981)

Extensive Theoretical Study on Various Low-Lying Electronic States of Silicon Monochloride Cation Including Spin−Orbit Coupling

“…As shown in Figure 1 and Table 3, only the ground state and the lowest excited state, a 3 Π state, have potential wells deeper than 1 eV. Our computed spectroscopic constants of the ground state reproduce the experimental data well, and the agreement is better than that achieved by Nishimura et al 17 As for the a 3 Π state, our calculated T e value of 31 832 cm -1 is in very good agreement with the value of 31 836 ( 3 cm -1 derived from experiment 10 for the a 3 Π 1 state, although the SO splitting will be discussed in section 3D. In addition, our calculated T e value is consistent with the experimental value of 31 778 ( 1613 cm -1 .…”

“…For the a 3 Π 0+ state, our computed ω e and ω e χ e values of 598.4 and 6.55 cm -1 are in very good agreement with the experimental values of 595.8 ( 1.0 and 6.62 ( 0.12 cm -1 ; and for the a 3 Π 1 state, our computational ω e and ω e χ e values of 598.9 and 6.71 cm -1 are also very close to the experimental values of 596.0 ( 1.8 and 6.75 ( 0.56 cm -1 . 10 The adiabatic excitation energies of the a 3 Π 0+ and a 3 Π 1 states obtained by us are 31 708 and 31 830 cm -1 , respectively, which are in excellent agreement with the experimental values of 31 721 ( 2 and 31 836 ( 3 cm -1 , 10 and the corresponding energy splitting of 122 cm -1 also closely matches the experimental value of 115 cm -1 . 10 The a 3 Π state crosses with the closely spaced (1) 3 Σ + , (1) 3 ∆, (1) 1 ∆, (1) 1 Σ -, (1) 3 Σstates and the (2) 1 Σ + state in the internuclear distance region of 2.3-2.7 Å, and when the SO coupling effects are introduced, the shape and character of the PECs would change distinctly, because these crossings are near the well bottoms of the six states.…”

“…10 The adiabatic excitation energies of the a 3 Π 0+ and a 3 Π 1 states obtained by us are 31 708 and 31 830 cm -1 , respectively, which are in excellent agreement with the experimental values of 31 721 ( 2 and 31 836 ( 3 cm -1 , 10 and the corresponding energy splitting of 122 cm -1 also closely matches the experimental value of 115 cm -1 . 10 The a 3 Π state crosses with the closely spaced (1) 3 Σ + , (1) 3 ∆, (1) 1 ∆, (1) 1 Σ -, (1) 3 Σstates and the (2) 1 Σ + state in the internuclear distance region of 2.3-2.7 Å, and when the SO coupling effects are introduced, the shape and character of the PECs would change distinctly, because these crossings are near the well bottoms of the six states. Because of this point, and the avoided crossing rule between different Ω states, the shapes of the PECs for the Ω states will differ from the pure Λ-S states evidently, and the PECs of the Ω states with potential wells would become unsmooth.…”

In search of molecular ions for optical cycling: a difficult road

“…studied experimentally and theoretically. [120][121][122][123] In particular, these ions were detected as afterglows of the corresponding tetrachloride in a rare gas originating due to a 3 Π → X 1 Σ + emission in the UV range. Previous ab initio calculations predicted that the A 1 Π state is either weakly bound or dissociative and lies above the a 3 Π state.…”

In Search of Molecular Ions for Optical Cycling: A Difficult Road

“…The low-lying states of monochloride ions CCl + , SiCl + , and GeCl + have been previously studied experimentally and theoretically. [120][121][122][123] In particular, these ions were detected as afterglows of the corresponding tetrachloride in a rare gas originating due to a 3 Π → X 1 Σ + emission in the UV range. Previous ab initio calculations predicted that the A 1 Π state is either weakly bound or dissociative and lies above the a 3 Π state.…”