Transitions between the spin-rotational levels of the (14)NH(+) radical in the v = 0 levels of its X (2)Pi and a (4)Sigma(-) states have been studied by the technique of laser magnetic resonance at far-infrared wavelengths. The data have been combined with a previous zero-field measurement of the J = 1 1/2 - 1/2 transition frequencies at 1.01 THz to determine a much improved set of molecular parameters for NH(+) in the X (2)Pi state; the major parameters for the a (4)Sigma(-) state have also been determined. A full determination of the hyperfine parameters for both (14)N and (1)H nuclei has been achieved for the first time. Accurate predictions of the transition frequencies between the low-lying levels of the radical in the absence of a magnetic field have also been made, including lambda-doubling frequencies for use by radio astronomers.
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http://dx.doi.org/10.1063/1.3160964 | DOI Listing |
J Phys Chem A
May 2024
Center for Accelerator Mass Spectrometry, Lawrence Livermore National Laboratory, Livermore, California 94550, United States.
A global diabatization scheme, based on the "valence-hole" concept, has been previously applied to model webs of avoided crossings that exist in four electronic-state symmetry manifolds of C (Π, Π, Σ, and Σ). Here, this model is extended to the electronically excited states of four more molecules: CN (Σ), N (Π), SiC (Π), and Si (Π). Many strangenesses in the spectroscopic observations (e.
View Article and Find Full Text PDFJ Chem Phys
April 2024
Department of Physics and Astronomy, University College London, Gower St., London WC1E 6BT, United Kingdom.
Multi-reference configuration interaction potential energy curves (PECs) and spin-orbit couplings for the X 2Π, A 2Σ+, 1 2Σ-, 1 4Σ-, and 1 4Π states of OH are computed and refined against empirical energy levels and transitions to produce a spectroscopic model. Predissociation lifetimes are determined by discretizing continuum states in the variational method nuclear motion calculation by restricting the calculation to a finite range of internuclear separations. Varying this range gives a series of avoided crossings between quasi-bound states associated with the A 2Σ+ and continuum states, from which predissociation lifetimes are extracted.
View Article and Find Full Text PDFPhys Chem Chem Phys
September 2023
Institut des Sciences Moléculaires, CNRS, Université de Bordeaux, F-33400 Talence, France.
We report the first experimental observation of single-photon ionization transitions of the SiC radical between 8.0 and 11.0 eV performed on the DESIRS beamline at the SOLEIL synchrotron facility.
View Article and Find Full Text PDFJ Chem Phys
April 2021
School of Physics, Peking University, Beijing 100871, People's Republic of China.
Accurate ab initio calculations of 3d transition metal monoxide molecules have attracted extensive attention because of their relevance in physical and chemical science as well as theoretical challenges in treating strong electron correlation. Meanwhile, recent years have witnessed the rapid development of the full configuration interaction quantum Monte Carlo (FCIQMC) method to tackle electron correlation. In this study, we carry out FCIQMC simulations to ScO, TiO, and VO molecules and obtain accurate descriptions of 13 low-lying electronic states (ScO Σ, Δ, Π; TiO Δ, Δ, Σ, Π, Φ; VO Σ, Φ, Π, Γ, Δ), including states that have significant multi-configurational character.
View Article and Find Full Text PDFJ Chem Phys
September 2019
Chemistry, School of Molecular Sciences, The University of Western Australia, 35 Stirling Highway, Crawley, Western Australia 6009, Australia.
The MgCH radical and its magnesium-25, carbon-13, and deuterated isotopologs have been isolated in low temperature neon matrices and examined by the matrix isolation electron spin resonance technique for the first time. The radicals were formed through the reactions of laser ablated natural abundance magnesium metal and magnesium-25 enriched magnesium metal with carbon-13 and deuterated isotopologs of acetone. The MgCH radical was shown to have a XΣ ground electronic state, and the magnetic parameters determined for this state were g = 2.
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