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1. A d 8 anti-Hund’s singlet insulator in an infinite-layer nickelate

   https://doi.org/10.1088/2515-7639/ac6040  

   Jin, Hyo-Sun ; Pickett, Warren E. ; Lee, Kwan-Woo ( April 2022 , Journal of Physics: Materials)

   The status of nickelate superconductors in relation to cuprate high temperature superconductors is one of the concepts being discussed in high temperature superconductivity in correlated transition metal oxides. New additions to the class of infinite layer nickelates can provide essential input relating to connections or distinctions. A recently synthesized compound Ba₂NiO₂(AgSe)₂, which contains isolated ‘infinite layer’ NiO₂planes, may lead to new insights. Our investigations have discovered that, at density functional theory mean field level, the ground state consists of an unusual$e_{\mathrm{g}}$singlet on the Ni²⁺ion arising from large but separate Mott insulating gaps in both$e_{\mathrm{g}}$orbitals, but with different, anti-Hund’s, spin directions of their moments. This textured singlet incorporates at the least new physics, and potentially a new platform for nickelate superconductivity, which might be of an unconventional form for transition metal oxides due to the unconventional undoped state. We include in this paper a comparison of electronic structure parameters of Ba₂NiO₂(AgSe)₂with a better characterized infinite layer nickelate LaNiO₂. We provide more analysis of thed⁸anti-Hund’s singlet that emerges in this compound, and consider a minimally correlated wavefunction for this singlet in an itinerant background, and begin discussion of excitations—real or virtual—that may figure into new electronic phases.

    

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2. Spectroscopic study of the 4f 7 6s 2 8 S 7/2∘ – 4f 7 ( 8 S ° ) 6s6p( 1 P ° ) 8 P 5/2,7/2 transitions in neutral europium-151 and europium-153: absolute frequency and hyperfine structure

   https://doi.org/10.1364/JOSAB.521181  

   Maruko, C. ; Çölmek, N_N ; Herd, M_T ; Ahrendsen, K_J ; Cabrales, B. ; Cannon, G. ; Davis, E. ; Guo, X_Y ; Karani, T. ; Wallace, A. ; et al ( April 2024 , Journal of the Optical Society of America B)

   We report on spectroscopic measurements on the 4f⁷6s²⁸S_7/2^∘−4f⁷(⁸S^∘)6s6p(¹P^∘)⁸P_5/2,7/2transitions at 466.32 nm and 462.85 nm, respectively, in neutral europium-151 and europium-153. The center of gravity frequencies for the 151 and 153 isotopes for both transitions are reported for the first time using saturated absorption spectroscopy. For the 6s6p(¹P^∘)⁸P_5/2state, the center of gravity frequencies were found to be 642,894,493.3(4) MHz and 642,891,693.3(9) MHz for the 151 and 153 isotopes, respectively. The hyperfine constants for the upper state were found to beA(151)=−157.01(3)MHz,B(151)=74.5(4)MHz andA(153)=−69.43(14)MHz,B(153)=191.0(26)MHz. These hyperfine values are all consistent with previously published results except forB(151) that has a small discrepancy. The isotope shift was found to be 2799.54(20) MHz, a small discrepancy with previously published results. For the 6s6p(¹P^∘)⁸P_7/2state, the center of gravity frequencies were found to be 647,708,930.6(6) MHz and 647,705,958.4(26) MHz for the 151 and 153 isotopes, respectively. The hyperfine constants for the upper state were found to beA(151)=−218.66(4)MHz,B(151)=−293.4(8)MHz andA(153)=−97.15(13)MHz,B(153)=−750(3)MHz. These values are all consistent with previously published results except forA(151) that has a small discrepancy. The isotope shift was found to be 2972.8(5) MHz, a small discrepancy with previously measured results.

    

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3. Proton-Induced Reactivity of NO – from a {CoNO} 8 Complex

   https://doi.org/10.1021/ja5064444  

   Rhine, Melody A. ; Rodrigues, Andria V. ; Urbauer, Ramona J. ; Urbauer, Jeffrey L. ; Stemmler, Timothy L. ; Harrop, Todd C. ( September 2014 , Journal of the American Chemical Society)
4. Interconversion of Molybdenum or Tungsten d 2 Styrene Complexes with d 0 1-Phenethylidene Analogues

   https://doi.org/10.1021/jacs.1c08086  

   Liu, Sumeng ; Boudjelel, Maxime ; Schrock, Richard R. ; Conley, Matthew P. ; Tsay, Charlene ( October 2021 , Journal of the American Chemical Society)
5. Dynamics of the isotope exchange reaction of D with H3+, H 2 D + , and D 2 H +

   https://doi.org/10.1063/5.0038434  

   Bowen, K. P. ; Hillenbrand, P.-M. ; Liévin, J. ; Savin, D. W. ; Urbain, X. ( February 2021 , The Journal of Chemical Physics)