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1. Measurements of ¹⁸ O ¹⁸ O and ¹⁷ O ¹⁸ O in the atmosphere and the role of isotope-exchange reactions: ¹⁸ O ¹⁸ O AND ¹⁷ O ¹⁸ O IN THE ATMOSPHERE

   https://doi.org/10.1029/2012JD017992  

   Yeung, Laurence Y.; Young, Edward D.; Schauble, Edwin A. (September 2012, Journal of Geophysical Research: Atmospheres)
2. Measurement of the ²⁷ Al ⁺ and ⁸⁷ Sr absolute optical frequencies

   https://doi.org/10.1088/1681-7575/abd040  

   Leopardi, Holly; Beloy, Kyle; Bothwell, Tobias; Brewer, Samuel M; Bromley, Sarah L; Chen, Jwo-Sy; Diddams, Scott A; Fasano, Robert J; Hassan, Youssef S; Hume, David B; et al (February 2021, Metrologia)

   null (Ed.)
3. Layered and Cubic Semiconductors A Ga M ′ Q ₄ ( A ⁺ = K ⁺ , Rb ⁺ , Cs ⁺ , Tl ⁺ ; M ′ ⁴⁺ = Ge ⁴⁺ , Sn ⁴⁺ ; Q ^2– = S ^2– , Se ^2– ) and High Third-Harmonic Generation

   https://doi.org/10.1021/jacs.0c08638  

   Friedrich, Daniel; Byun, Hye Ryung; Hao, Shiqiang; Patel, Shane; Wolverton, Chris; Jang, Joon Ik; Kanatzidis, Mercouri G. (October 2020, Journal of the American Chemical Society)

   null (Ed.)
4. 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 (January 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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5. Probing the Electronic Manifold of MgCl with Millimeter-Wave Spectroscopy and Theory: (3) ² Σ ⁺ and (4) ² Σ ⁺ States

   https://doi.org/10.1021/acs.jpca.4c05458  

   Herman, T J; Ravi, R; Schuurman, M S; DeYonker, N J; Field, R W; Ziurys, L M (November 2024, The Journal of Physical Chemistry A)

   The millimeter/submillimeter spectrum of magnesium chloride (MgCl) has been observed in two new electronic excited states, (3)2Σ+ and (4)2Σ+, using direct absorption methods. The molecule was synthesized in a mixture of Cl2, argon and magnesium vapor. For the (3)2Σ+ state, multiple rotational transitions were measured in the v = 0 level for all six isotopologues (24Mg35Cl, 24Mg37Cl, 25Mg35Cl, 25Mg37Cl, 26Mg35Cl, 26Mg37Cl), as well as up to v = 13 for 24Mg35Cl. For the (4)2Σ+ state, less intense spectra were recorded for 24Mg35Cl (v = 0-2). Equilibrium rotational parameters were determined for both states for 24Mg35Cl, as well as rotational constants and 25Mg hyperfine parameters for the other isotopologues. A perturbation was observed between rotational levels of the two states due to an avoided crossing. Computations were also carried out at the CASPT2 and MRCISD+Q levels, and the resulting bond lengths for (3)2Σ+ and (4)2Σ+ states agree well with the experimental values of re = 2.536 Å and 2.361 Å. The computations show that the (3)2Σ+ state has a double-well potential; however, the state behaves as a single well with unperturbed vibrational levels up to v = 13 due to non-adiabatic coupling with the (4)2Σ+ state. 

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