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Current and Future Applications of Diamondoids and Their Derivatives
Published in Sven Stauss, Kazuo Terashima, Diamondoids, 2017
A disadvantage of magnetic resonance force microscopy (MRFM) is that it only performs well at cryogenic temperatures and in vacuum, which is not compatible with many biological (and other) applications. Therefore we are trying to come up with other ideas that might allow us to do the same experiments under ambient conditions.
Nanoscale Spectroscopy with Applications to Chemistry
Published in Sarhan M. Musa, Nanoscale Spectroscopy with Applications, 2018
Making MRFM applicable for high-resolution NMR spectroscopy offers enormous potentials and is challenging. Exploiting the exquisite sensitivity and the very high imaging resolution of the MRFM enables investigation of the objects in the nanometer scale, which is much smaller than inductive detection. The strong field inhomogeneity associated with the MRFM gradient is detrimental for high-resolution magnetic resonance applications. While superconducting magnets used in standard NMR are presently able to provide magnetic fields that vary less than ≈109 over the entire sample volume, resonant slices in MRFM have a width of ≈104, that is, spectral resolution is reduced by about five orders of magnitude. There is a possibility to measure the mechanical torque on a sample by transfer of spin angular momentum. This method, which does not require a field gradient, was investigated by Alzetta et al. for ESR [44,45]. Leskowitz et al. and Madsen et al. [46,47] developed an alternative approach that was used with NMR. They measured the field gradient of the sample rather than that of the gradient magnet. Both attempts however employed force detection for sensitivity enhancement and essentially lacked the high imaging capacity of the genuine MRFM invented by Sidles. The key challenge was to overcome the resolution-limiting effect of the gradient magnet, which is the core strategy in molecular structure determination by NMR via the selective suppression or enhancement of specific spin interactions. The presence of dipolar couplings manifests close spatial proximity between two nuclear spins, and by measuring the coupling constants, quantitative distance information can be obtained. Chemical bonds often result in contact couplings (J-couphngs), which can be used to investigate the bonding network within the molecule. Chemical shifts are often characteristic for their molecular environment and allow in many cases to assign the atom to a certain functional group. The effect of a certain interaction can be suppressed by canceling the associated Hamiltonian during the observed coherent evolution of the spins. This can be done either by continuously decoupling or by introducing dephasing and rephasing periods while changing the sign of the Hamiltonian in between (“echo” methods). Sophisticated rf-pulse sequences have been developed that allow manipulating the Hamiltonian nearly at will.
Light, the universe and everything – 12 Herculean tasks for quantum cowboys and black diamond skiers
Published in Journal of Modern Optics, 2018
Girish Agarwal, Roland E. Allen, Iva Bezděková, Robert W. Boyd, Goong Chen, Ronald Hanson, Dean L. Hawthorne, Philip Hemmer, Moochan B. Kim, Olga Kocharovskaya, David M. Lee, Sebastian K. Lidström, Suzy Lidström, Harald Losert, Helmut Maier, John W. Neuberger, Miles J. Padgett, Mark Raizen, Surjeet Rajendran, Ernst Rasel, Wolfgang P. Schleich, Marlan O. Scully, Gavriil Shchedrin, Gennady Shvets, Alexei V. Sokolov, Anatoly Svidzinsky, Ronald L. Walsworth, Rainer Weiss, Frank Wilczek, Alan E. Willner, Eli Yablonovitch, Nikolay Zheludev
In recent years, NV colour centres in diamond have attracted intense interest as precision quantum sensors with wide-ranging applications in both the physical and life sciences. Most prominently, NV diamond has been shown to provide a combination of magnetic field sensitivity and nanoscale spatial resolution that is unmatched by any existing technology – including SQUIDs, atomic magnetometers and magnetic resonance force microscopy – while operating over a wide range of temperatures from cryogenic to well above room temperature in a robust, solid-state system [56,167,264]. Importantly, since NV centres are atomic-sized defects and can be localized very close to the diamond surface, they can be brought to within a few nanometres of the sample of interest, greatly enhancing the sample’s magnetic field at the position of the NV sensor (e.g. dipole fields fall off as 1/r3) and enabling nanometre scale resolution. For magnetic field sensing, one optically measures the effect of the Zeeman shift on the NV ground-state spin levels. Similarly, NV diamond can provide nanoscale electric field sensing via a linear Stark shift in the NV ground-state spin levels induced by interactions with the crystalline lattice [57]; as well as nanoscale temperature sensing via a change in the zero-magnetic-field splitting between the NV spin levels [58]. In addition, NV diamond has other enabling properties for both physical and life science applications, including: fluorescence that typically does not bleach or blink; ability to be fabricated into a wide range of forms such as nanocrystals, atomic force microscope (AFM) tips, and bulk chips with NVs a few nanometers from the surface or uniformly distributed at high density; compatibility with most materials (metals, semiconductors, liquids, polymers et al.); benign chemical properties; and good endocytosis and no cytotoxicity for diamond nanocrystals and other structures used in sensing and imaging of living biological cells and tissues.