Diamond rotors

• Published in: Journal of magnetic resonance (1997) 2023-07, Vol.352, p.107475-107475, Article 107475
• Main Authors: Golota, Natalie C., Fredin, Zachary P., Banks, Daniel P., Preiss, David, Bahri, Salima, Patil, Prashant, Langford, William K., Blackburn, Camron L., Strand, Erik, Michael, Brian, Dastrup, Blake, Nelson, Keith A., Gershenfeld, Neil, Griffin, Robert
• Format: Article
• Language: English
• Subjects: Diamond; Diamond rotors; High frequency spinning; INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; Laser machining; Magic angle spinning; Magnetic Resonance Spectroscopy - methods; Microwaves; Proteins
• ISSN: 1090-7807; 1096-0856
• DOI: 10.1016/j.jmr.2023.107475

[Display omitted] •Laser micromachining method to produce high aspect ratio, 0.7 mm diamond rotors with less than 0.05° internal taper angle.•Demonstrate ωr/2π = 111.000 ± 0.004 kHz, with stable spinning up to 124 kHz.•Proton detected heteronuclear correlations obtained using diamond rotors.•Proof of concept use of diamond rotors is an initial step toward higher MAS frequencies and more efficient DNP. The resolution of magic angle spinning (MAS) nuclear magnetic resonance (NMR) spectra remains bounded by the spinning frequency, which is limited by the material strength of MAS rotors. Since diamond is capable of withstanding 1.5–2.5x greater MAS frequencies, compared to state-of-the art zirconia, we fabricated rotors from single crystal diamond. When combined with bearings optimized for spinning with helium gas, diamond rotors could achieve the highest MAS frequencies to date. Furthermore, the excellent microwave transmission properties and thermal conductivity of diamond could improve sensitivity enhancements in dynamic nuclear polarization (DNP) experiments. The fabrication protocol we report involves novel laser micromachining and produced rotors that presently spin at ωr/2π = 111.000 ± 0.004 kHz, with stable spinning up to 124 kHz, using N2 gas as the driving fluid. We present the first proton-detected 13C/15N MAS spectra recorded using diamond rotors, a critical step towards studying currently inaccessible ex-vivo protein samples with MAS NMR. Previously, the high aspect ratio of MAS rotors (∼10:1) precluded fabrication of MAS rotors from diamond.