Ultrashield 9.4 t avance 1 spectrometer

The ²⁷Al SMC results and the nutation curve for ⁷Li metal were obtained on a Bruker Ultrashield 9.4 T Avance I spectrometer operating at 155.5 MHz for ⁷Li and 104.3 MHz for ²⁷Al. The ⁷Li nutation curve was acquired using a Bruker ¹H²⁷Li WB40 birdcage coil on a strip of natural abundance lithium metal (Aldrich 99.9%) cut to ca. 0.4 × 8 × 15 mm and sealed inside a 10 mm NMR tube. The aluminium SMC experiments were acquired on powdered aluminium samples with small (Alfa Aesar, APS 3.0–4.5 micron, 97.5% metals basis) and large (Alfa Aesar, −40 + 325 mesh, 99.8% metals basis) particle sizes, using a 4 mm solid-state HX Bruker probe (chosen for its strong B₁ field, samples were not spun). The aluminium powders were diluted 1:1 by weight with CaCl₂ in order to ensure a more uniform B₁ field. A Bruker Avance-500 NMR spectrometer with a BBO probe tuned to ⁷Li at 194.4 MHz was used to collect data for the SMC sequence on a natural abundance lithium metal strip (Aldrich 99.9%) cut to ca. 0.4 × 3 × 6 mm and sealed inside a 5 mm NMR tube. In all cases spectra were acquired on resonance with the center of the metal peak and the plotted intensity profiles correspond to the on-resonance position in the spectrum.
SEM images of the powdered aluminium samples was obtain using a MERLIN (Carl Zeiss) field emission scanning electron microscope (FESEM) with an SE2 (Everhart-Thornley type) detector.

The MRI experiments were performed on a Bruker Ultrashield 9.4T Avance I spectrometer containing a Bruker Mini0.75 gradient assembly and operating at 400.1 MHz for ¹H. A Bruker MiniWB57 imaging probe was used to collect all of the data, with a Bruker WB57 40-mm i. d. coil insert for ¹H experiments. 2D ¹H MRI experiments were performed using a slice-selective 2D FLASH sequence implemented in Paravision 5.1, using a hermite pulse shape with pulse duration of 1 ms, an echo time (TE) of at least 2.45 ms, repetition time (TR) of 100 ms, nominal flip angle (α) of 15°, and 12 scans for signal averaging. The field of view (FOV) was 51.2 × 51.2 mm in the x and z direction, respectively, with a k-space consisting of 128 phase-encoded points in the x direction and 128 points in the readout direction along z. This resulted in a 2D image with slice thickness of 1 mm and an isotropic resolution of 400 μm, with a total experiment time of about 2.5 min.