  A new pathway to nuclear magnetic resonance spectroscopy in high pressure
diamond anvil cells is introduced, using inductively coupled broadband passive
electro-magnetic lenses to locally amplify the magnetic flux at the isolated
sample, leading to an increase in sensitivity. The lenses are adopted for the
geometrical restrictions imposed by a toroidal diamond indenter cell, and yield
high signal-to-noise ratios at pressures as high as 72 GPa, at initial sample
volumes of only 230 pl. The corresponding levels of detection, LODt, are found
to be up to four orders of magnitude lower compared to formerly used solenoidal
micro-coils in diamond anvil cells, as shown by Proton-NMR measurements on
paraffin oil. This approach opens up the field of ultra-high pressure sciences
for one of the most versatile spectroscopic methods available in a pressure
range unprecedended up to now.
