VUV–VIS FT spectroscopy of the rare 13C18O isotopologue of carbon monoxide: Analysis of the A1Π(v = 1) multiply-perturbed level

https://doi.org/10.1016/j.saa.2022.121367Get rights and content
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Highlights

  • 11 bands of 13C18O were obtained by two complementary FT-VIS and FT-VUV methods.

  • Deperturbation analysis of 13C18O A1Π(1) based on 598 lines was performed.

  • The indirect a3Π(v = 12) ∼ A1Π(v = 1) interaction were detected and analysed.

  • 112 terms of B1Σ+(v = 0) Jmax = 50 and C1Σ+(v = 0) Jmax = 60 were calculated.

  • 23 parameters for A(1), I(2), d(6), e(3), D(1), a(12) and couplings were determined.

Abstract

Ro-vibronic spectra of the 13C18O carbon monoxide isotopologue were obtained with (i) emission spectroscopy in the visible region using a Bruker IFS 125HR spectrometer (University of Rzeszów) and (ii) vacuum-ultraviolet absorption spectroscopy using the wave-front-division spectrometer on the DESIRS beamline of the SOLEIL synchrotron. A deperturbation analysis of the 13C18O A1Π(v = 1) level was conducted from 598 observed transitions from the B1Σ+ - A1Π(0, 1), C1Σ+ - A1Π(0, 1), A1Π - X1Σ+(1, 0), B1Σ+ - X1Σ+(0, 0), C1Σ+ - X1Σ+(0, 0), I1Σ - X1Σ+(2, 0) bands and five further nominally forbidden bands. An effective Hamiltonian and term-value fitting analysis was implemented. Consequently, 135 parameters were floated: 23 molecular parameters, including molecular constants for A1Π(v = 1), I1Σ(v = 2), d3Δ(v = 6), e3Σ(v = 3) and D1Δ(v = 1); rotation-electronic (L-uncoupling) mixing of A1Π(v = 1) ∼ [D1Δ(v = 1), I1Σ(v = 1), I1Σ(v = 2)] and spin–orbit interaction parameters for A1Π(v = 1) ∼ [d3Δ(v = 6), e3Σ(v = 3), aʹ3Σ+(v = 11)]; the spin–orbit/spin-electronic/L-uncoupling a3Π(v = 12) ∼ d3Δ(v = 5) and spin–orbit a3Π(v = 12) ∼ [D1Δ(v = 1), I1Σ(v = 2)] perturbation parameters; as well as 112 ro-vibronic term values of B1Σ+(v = 0) up to J = 50 and C1Σ+(v = 0) up to J = 60. The significant, indirect a3Π(v = 12) ∼ [e3Σ(v = 2, 3), d3Δ(v = 5, 6)] ∼ A1Π(v = 1) spin–orbit/spin-electronic/L-uncoupling interaction and a3Π(v = 12) ∼ [I1Σ(v = 2), D1Δ(v = 1)] ∼ A1Π(v = 1) spin–orbit/L-uncoupling interaction were detected and analysed. Thus, this study, using modern experimental methods and deperturbation analysis, leads to a much improved description in terms of molecular constants and interaction parameters, compared to previous studies of the A1Π(v = 1) energy region in the 13C18O isotopologue. This research is a continuation of the studies on the A1Π state and its numerous perturbers in the CO isotopologues made by our team.

Keywords

High-resolution spectra
VUV-FT absorption and synchrotron spectroscopy
VIS-FT emission spectroscopy
CO
Carbon monoxide
13C18O A1Π(v = 1) multiply-perturbed level
Deperturbation analysis
Spin-orbit and spin-electronic and rotation-electronic (L-uncoupling) and spin-spin interactions

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