Chapter 26 - A new gasket material for higher resolution NMR in diamond anvil cells

Abstract

This chapter proposes a new gasket material that gives higher resolution in high pressure Nuclear magnetic resonance (NMR) spectroscopy carried out in diamond anvil cells. The magnetic susceptibility of the gasket is similar to that of the diamond and the sample, thus, significantly reducing the disturbance of the static sample field. NMR line widths are reduced to 0.8 ppm for methanol samples at 0.9 GPa, which enables resolution of the methyl and hydroxyl protons in the observed spectra. The spin-spin relaxation times of these resonances are separately determined. Nuclear magnetic resonance (NMR) is a radio frequency (rf) spectroscopy that gives unique information about local structure and dynamics surrounding specific nuclear spins. NMR spectrum gives the local structure and the spin relaxation time gives the local dynamics. Technical challenges of combining NMR with the diamond anvil cell (DAC) techniques have been answered in a variety of approaches. These issues include: (1) intrinsic low sensitivity of NMR, (2) small sample volume of conventional DACs, (3) shielding effects of the metallic gasket, (4) prohibition of using ferromagnetic components, and (5) the limited working space in the magnet.