Isotropie and Anisotropie Nuclear Magnetic Shielding of ¹¹³Cd in Cadmiumhalides, Cadmiumchalcogenides and in Cadmiumcarbonate

Abstract

The NMR signals of

Revealing the Surface Structure of CdSe Nanocrystals by Dynamic Nuclear Polarization-Enhanced 77Se and 113Cd Solid-State NMR Spectroscopy

“…The isotropic 113 Cd chemical shifts observed in the indirect dimension of the 2D CP-MAT spectra provide clear information about the identity of the atoms coordinating Cd, while the sideband manifolds observed in the direct dimension allow determination of anisotropic chemical shift tensor parameters that report on the symmetry of the Cd atoms. ,, Interestingly, the 2D CP-MAT spectra of the platelets and spheroids are similar, with both showing four distinct isotropic 113 Cd NMR signals visible in the indirect dimension, although there are differences in the relative signal intensities between the two samples and some slight differences in isotropic chemical shifts (Figure S7). The first signal occurs at an isotropic chemical shift of approximately −60 ppm, which matches the previously reported chemical shift for bulk CdSe. ,,,,, Therefore, this signal corresponds to CdSe 4 sites residing in the core or subsurface regions of the CdSe NCs. As expected, this site has a small chemical shift anisotropy (CSA) (Ω < 200 ppm) consistent with the symmetric, tetrahedral arrangement of Se atoms.…”

“…The first signal occurs at an isotropic chemical shift of approximately −60 ppm, which matches the previously reported chemical shift for bulk CdSe. 49,50,56,57,59,81 Therefore, this signal corresponds to CdSe 4 sites residing in the core or subsurface regions of the CdSe NCs. As expected, this site has a small chemical shift anisotropy (CSA) (Ω < 200 ppm) consistent with the symmetric, tetrahedral arrangement of Se atoms.…”

Alloyed Crystalline CdSe1‐xSxSemiconductive Nanomaterials – A Solid State113Cd NMR Study

“…The ability of donating electrons to the Cd(II) outer p orbitals and withdrawing electrons from the Cd(II) valence d orbitals is proportional to the bonding elemental electronegativity. 113 Cd chemical shifts for CdS, CdSe and CdTe were reported early in the literature, [46] and we have measured the 113 Cd NMR chemical shifts of CdS, CdSe and CdTe under the same conditions (Table 2); the experimental data is very close to that reported in the literature. The 113 Cd NMR chemical shifts of CdS, CdSe and CdTe fit very well to the electronegativity model.…”

“…[27] However some data related to pure individual phase for bulk and nanoparticles, e. g., CdS, CdSe and CdTe were available and two types of chemical shift references were used, either solid Cd(NO 3 ) 2 4H 2 O [35,36,38,39] or 0.1 M Cd(ClO 4 ) 2 6H 2 O in water. [40,46] Because there is a 100 ppm difference in the chemical shifts of these two reference compounds, one must exam literature data carefully when comparing obtained values with reported values. [50,64] All our chemical shift data measured here were all referenced to 0.1 M Cd(ClO 4 ) 2 6H 2 O in water.…”

Nuclear Magnetic Resonance (NMR) Study of Cd2+ Sorption on Montmorillonite

“…The CP sequence incorporated a 90 ~ proton flip-back pulse immediately after the acquisition period to reduce the recycle delay necessary between scans. All MAS and CP-MAS NMR spectra were recorded on samples equilibrated at room humidity and are referred to a 0.1 M Cd(C104)2 solution (Nolle, 1978).…”