15N magnetic shielding anisotropies in 15N15NO

Abstract

The 15N magnetic shielding anisotropies in nitrous oxide (15N15NO) have been determined using a pulsed FT NMR spectrometer. The shielding anisotropies obtained from the temperature dependence of the nematic phase chemical shifts are 512 ± 10 ppm (central 15N) and 369 ± 15 ppm (end 15N). The values obtained from the nematic-isotropic phase difference method are 505 ± 10 ppm (central 15N) and 366 ± 10 ppm (end 15N). Theoretical estimates of the anisotropies from the so-called atom dipole method are also reported. The indirect scalar coupling constant has been assigned to be negative. The signs of the 15N spin-rotation constants are predicted to be positive.

Determination of the singlet state lifetime of dissolved nitrous oxide from high field relaxation measurements

“…(6) can be found in the literature; the spin-rotation tensors of the linear N 2 O take a simple form and can be described by a single value for each nucleus (C ⊥, central = 3.35 kHz, C ⊥, terminal = 2.48 kHz 19 ), and the CSA tensors can be characterized by a single value σ = σ || − σ ⊥ : σ central = 505 ppm, σ terminal = 366 ppm. 20 The size of the through-space dipolar coupling can be calculated and agrees well with a measured value of 865 Hz from powder-pattern solid state spectra (data not shown). Because CSA exceeds the dipolar coupling by over an order of magnitude, intramolecular dipolar relaxation can be neglected and is not discussed further.…”

Lineshape-based polarimetry of dynamically-polarized 15N2O in solid-state mixtures

“…4 shows the NMR spectrum along with the model line shape based on the best-fit parameters listed in Table 1. The J-coupling was set to the literature value –8.7 Hz [14,18]. Our isotropic chemical shift difference $({\delta }_2^{\mathrm{iso}}-{\delta }_1^{\mathrm{iso}})$ is in reasonable agreement with room-temperature data: 75 ppm in nematic-phase 15 N 2 O [18] and 82.3 ppm in isotropic solution [12].…”

“…1A shows the evolution of 15 N NMR spectra during DNP in sample I. Four observed powder-pattern lineshape components are attributed to the chemical-shift anisotropy (CSA) tensors of the two 15 N nuclei [18], further split by intramolecular dipolar coupling between them [19]. Fig.…”

Anisotropic chemical shifts and spin rotation constants of 15N from liquid and solid state NMR: Nitrobenzene

“…This has some justification, because the moment of inertia tensor is almost axial with respect to the twofold axis of the molecule (see also below). Then T~f is given by (10)(11)(12): [3] where p is the ratio of the correlation times of reorientation perpendicular and parallel to the symmetry axis (p:==: TC.L/TclI) and P is the angle between the molecular vector of interest and the symmetry axis of the rotational diffusion tensor. If we tentatively use the effective correlation times Te found from the dipolar rate of the 1 3 Cmeasurements (Table 1), we get from Eq.…”