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Identification of Microplastics and Nanoplastics and Associated Analytical Challenges
Published in Hyunjung Kim, Microplastics, 2023
Notably, the natural abundance of an NMR-active atomic nucleus and the gyromagnetic ratio (measured between the nuclear magnetic moment and spin angular momentum denoted by γ) directly affect the sensitivity to that nucleus. Hence, the abundant nuclei with a high γ-value (e.g., 1H and 19F) are the most responsive to the NMR technique.
Magnetic Resonance Imaging
Published in Shoogo Ueno, Bioimaging, 2020
A nucleus has spin and generates a magnetic moment derived from this. Intuitively, spin corresponds to the rotation of a nucleus, and magnetic moment means that the nucleus behaves as a small magnet with N and S poles. NMR is caused by the interaction between the nuclear magnetic moment and an external magnetic field.
Interplay between unconventional superconductivity and heavy-fermion quantum criticality: CeCu2Si2 versus YbRh2Si2
Published in Philosophical Magazine, 2018
M. Smidman, O. Stockert, J. Arndt, G. M. Pang, L. Jiao, H. Q. Yuan, H. A. Vieyra, S. Kitagawa, K. Ishida, K. Fujiwara, T. C. Kobayashi, E. Schuberth, M. Tippmann, L. Steinke, S. Lausberg, A. Steppke, M. Brando, H. Pfau, U. Stockert, P. Sun, S. Friedemann, S. Wirth, C. Krellner, S. Kirchner, E. M. Nica, R. Yu, Q. Si, F. Steglich
The data shown in Figure 5(c) represent the molar specific heat of the Yb-derived nuclear spins as ΔC(T)/T measured at B = 2.4 mT; ΔC(T) was obtained by subtracting the nuclear quadrupole contribution (which is field dependent only in higher order) from the raw data at B = 2.4 mT [20]. Because of their weak hyperfine couplings, both the 103Rh and 29Si isotopes do not add to the specific heat in the temperature regime T ≥ 1 mK. Here, only the contributions of 171Yb (nuclear spin I = 1/2) and 173Yb (I = 5/2) with natural abundances of about 15% each, are relevant – these nuclear Yb spins being randomly distributed. ΔC(T)/T displays a pronounced second-order phase transition at TA ≃ 2 mK. The gigantic jump anomaly of ≃ 1500 JK−2mol−1 clearly indicates that this transition involves predominantly nuclear degrees of freedom. On the scale defined by the specific-heat results, it is clear that any 4f-electronic and phonon contribution is completely negligible below about 10 mK [20]. Therefore, as no phase-transition anomaly is resolved at B ≃ 60 mT, this transition seen in the specific-heat results must indicate the onset of nuclear AF order. Interestingly, while the specific heat is probing only the nuclear degrees of freedom, the magnetic measurements presented in Figure 5(a,b) display the response exclusively by the 4f – electron spins: because of the small nuclear magnetic moment, a purely nuclear magnetic phase transition would not be resolved by either dc-magnetisation or ac-susceptibility.
Important components for accurate hyperfine coupling constants: electron correlation, dynamic contributions, and solvation effects
Published in Molecular Physics, 2020
Sigurd Vogler, Johannes C. B. Dietschreit, Laurens D. M. Peters, Christian Ochsenfeld
For methods beyond HF or DFT, the respective energy equation needs to be perturbed with respect to the nuclear magnetic moment of nucleus k [55]. Thus, analytic gradients of the MP2 expression are required both for HFCCs at the MP2-level and at the DH-DFT level. We resort to our RI-CDD MP2 gradients [47] and the selected-nuclei ansatz [48] in the present work to efficiently obtain the correlation contributions also for large systems.
Vibrational magnetism and the strength of magnetic dipole transition within the electric dipole forbidden v 2 + v 3 absorption band of carbon dioxide
Published in Molecular Physics, 2021
At the same time, the electronic magnetic moment tends to compensate consecutively the nuclear magnetic moment. It is important to realise that the smallness of a non-adiabatic effect is compensated by the electrons gyromagnetic ratio being much in excess of that nuclear [18,19].