Perturbations in the 7(16) and 8(18) mixed singlet/triplet levels of ã (1)A(1)(0,0,0) methylene, CH(2), have been reinvestigated by frequency-modulated laser sub-Doppler saturation spectroscopy. The hyperfine structure was completely resolved for both the predominantly singlet and the predominantly triplet components of these mixed rotational levels using b̃ (1)B(1)-ã (1)A(1) optical transitions near 12 200 cm(-1) with megahertz resolution. The mixing coefficients were obtained from the observed hyperfine splittings and a two-level deperturbation model. The analysis also determines the energy separation of the unperturbed zero-order levels and the unperturbed hyperfine splittings for the triplet perturbing levels 6(15) X̃ (3)B(1)(0,3,0) and 9(37) X̃ (3)B(1)(0,2,0).
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http://dx.doi.org/10.1063/1.3502084 | DOI Listing |
Inorg Chem
December 2024
Centre for Materials Science and Nanotechnology (SMN), Department of Chemistry, University of Oslo, Oslo N-0371, Norway.
We present the magnetic properties of the chiral, polar, and possibly magnetoelectric antiperovskite β-FeSeO as derived from magnetization and specific-heat measurements as well as from powder neutron diffraction and Mössbauer experiments. Our macroscopic data unambiguously reveal two magnetic phase transitions at ≈ 103 K and ≈ 78 K, while Rietveld analysis of neutron powder diffraction data reveals a noncollinear antiferromagnetic structure featuring magnetic moments in the - plane of the trigonal structure and a ferromagnetic moment along . The latter is allowed by symmetry between and , weakly visible in the magnetization data yet unresolvable microscopically.
View Article and Find Full Text PDFSpectrochim Acta A Mol Biomol Spectrosc
February 2025
Laboratory of Biochemistry, Institute of Biochemistry and Physiology of Plants and Microorganisms - Subdivision of the Federal State Budgetary Research Institution Saratov Federal Scientific Center of the Russian Academy of Sciences, Prosp. Entuziastov, 13, 410049 Saratov, Russia. Electronic address:
In this study, we analyze a series of molecules belonging to the C(M) molecular symmetry group which are characterized by several conformers. The use of molecular symmetry at each stage of calculating the energy of stationary torsional states is demonstrated. In particular, the importance is shown of preliminary symmetrization of physical characteristics of the molecules obtained by quantum chemical calculations.
View Article and Find Full Text PDFJ Phys Condens Matter
October 2024
School of Physical Science and Technology, Lanzhou University, Lanzhou 730000, People's Republic of China.
There has been controversy about the driving force of the nematic order in the FeSe superconductor. Here, we present a detailed study of theFe Mössbauer spectra of FeSe single-crystal powders, focusing on the temperature dependences of the hyperfine parameters in the vicinity of the nematic transition temperature,∼ 90 K. The nematicity-induced splitting ofandbands, obtained from the anomalous increase in quadrupole splitting near, starts at 143 K.
View Article and Find Full Text PDFPhys Chem Chem Phys
October 2024
Fachbereich Chemie, Philipps-Universität Marburg, Hans-Meerwein-Straße 4, 35043 Marburg, Germany.
Nuclear spin isomers of molecules play a pivotal role in our understanding of quantum mechanics and can have significant implications for various fields. In this work, we report the isolation and characterization of stable nuclear spin isomers as well as conformational isomers of a reactive compound, namely carbonyl diisothiocyanate. It can exist as three rotational conformers, two of which, the - and -, were observed in a pulsed supersonic jet by chirped pulse Fourier transform microwave spectroscopy in the 2-12 GHz frequency region.
View Article and Find Full Text PDFJ Chem Phys
September 2024
Center for Free-Electron Laser Science CFEL, Deutsches Elektronen-Synchrotron DESY, Notkestrasse 85, 22607 Hamburg, Germany.
We computationally studied the effect of nuclear-quadrupole interactions on the field-free impulsive alignment of different asymmetric-top molecules. Our analysis is focused on the influence of the hyperfine- and rotational-energy-level structures. These depend on the number of nuclear spins, the rotational constants, and the symmetry of the tensors involved in the nuclear spin and external field interactions.
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