ABSTRACT
Extending magnetic resonance imaging to the atomic scale has been a long-standing aspiration, driven by the prospect of directly mapping atomic positions in molecules with three-dimensional spatial resolution. We report detection of individual, isolated proton spins by a nitrogen-vacancy (NV) center in a diamond chip covered by an inorganic salt. The single-proton identity was confirmed by the Zeeman effect and by a quantum coherent rotation of the weakly coupled nuclear spin. Using the hyperfine field of the NV center as an imaging gradient, we determined proton-NV distances of less than 1 nm.
ABSTRACT
We present measurements of spin relaxation times (T1, T1ρ, T2) on very shallow (â²5 nm) nitrogen-vacancy centers in high-purity diamond single crystals. We find a reduction of spin relaxation times up to 30 times compared to bulk values, indicating the presence of ubiquitous magnetic impurities associated with the surface. Our measurements yield a density of 0.01-0.1µB/nm2 and a characteristic correlation time of 0.28(3) ns of surface states, with little variation between samples and chemical surface terminations. A low temperature measurement further confirms that fluctuations are thermally activated. The data support the atomistic picture where impurities are associated with the top carbon layers, and not with terminating surface atoms or adsorbate molecules. The low spin density implies that the presence of a single surface impurity is sufficient to cause spin relaxation of a shallow nitrogen-vacancy center.
ABSTRACT
We report successful introduction of negatively charged nitrogen-vacancy (NV(-)) centers in a 5 nm thin, isotopically enriched ([(12)C] = 99.99%) diamond layer by CVD. The present method allows for the formation of NV(-) in such a thin layer even when the surface is terminated by hydrogen atoms. NV(-) centers are found to have spin coherence times of between T2 ~ 10-100 µs at room temperature. Changing the surface termination to oxygen or fluorine leads to a slight increase in the NV(-) density, but not to any significant change in T2. The minimum detectable magnetic field estimated by this T2 is 3 nT after 100 s of averaging, which would be sufficient for the detection of nuclear magnetic fields exerted by a single proton. We demonstrate the suitability for nanoscale NMR by measuring the fluctuating field from ~10(4) proton nuclei placed on top of the 5 nm diamond film.
ABSTRACT
We experimentally demonstrate a simple and robust protocol for the detection of weak radio-frequency magnetic fields using a single electron spin in diamond. Our method relies on spin locking, where the Rabi frequency of the spin is adjusted to match the MHz signal frequency. In a proof-of-principle experiment we detect a 7.5 MHz magnetic probe field of ~40 nT amplitude with <10 kHz spectral resolution. Rotating-frame magnetometry may provide a direct and sensitive route to high-resolution spectroscopy of nanoscale nuclear spin signals.
ABSTRACT
In meat samples from 2 hunted red deer (Cervus elaphus) of different origins (region Ilanz, region Filisur) large-scale greenish tissue discolorations with a gelatinous change of fascia were observed and diagnosed as eosinophilic fasciitis. Sarcocystis hjorti, a recently described Sarcocystis species in red deer and moose in Norway, was found as the causing agent. Foxes are regarded as final hosts in the development cycle of this parasite. Factors leading to such cases of eosinophilic fasciitis due to sarcosporidiosis, which is widespread in farm and wild ruminants and is normally inapparent are largely unknown. According to meat inspection directives carcasses with such discolorations have to be declared unfit for human consumption.
