Browsing by Subject "Nuclear magnetic resonance force microscopy"

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    Analysis of crystalline ammonium hexafluorophosphate using nuclear magnetic resonance force microscopy (NMRFM) and design and construction of a dynamical room-temperature NMRFM microscope
    (2011-08) Cárdenas, Rosa Elia, 1980-; Markert, John T.; de Lozanne, Alejandro; MacDonald, Allan; Yao, Zhen; Hoffman, David W.
    In this dissertation I explain the theoretical and experimental details of nuclear magnetic resonance force microscopy (NMRFM). I report the data that I have collected on ammonium hexafluorophosphate at room temperature using NMRFM. This experiment measured cantilever deflection as a function of applied magnetic field. I also report on the progress of a new dynamical room-temperature NMRFM microscope. I describe the new probe and its advantages over the previous generation probe and I show the current calibration measurements.
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    Development of variable temperature NMR force microscopy : proton spin relaxation measurements in ammonium sulfate
    (2012-08) Manzanera Esteve, Isaac Vicente, 1977-; Markert, John T.; de Lozanne, Alejandro; Li, Xiaoqin; Yao, Zhen; Goodenough, John
    Nuclear magnetic resonance force microscopy (NMRFM) of a micron size sample of ammonium sulfate was performed by measuring the cantilever deflection produced by coupling the magnetic force to a mechanical cantilever at its resonance frequency. Spin-lattice and spin-spin relaxation measurements were obtained with our newly developed NMRFM probe. A system with more advanced positioning, acquisition and analysis has been fabricated. A new device in which a semi-automatic system performs nanoposition control, spin manipulation, dynamical measurements, and data analysis has been demonstrated to be successful. The new system has proven to be an improvement with respect to other versions of NMRFM probes, thanks to its versatility for pulse sequence designs, faster data acquisition, and automatic analysis of the information. This thesis presents an explanation of the theoretical details of nuclear magnetic resonance force microscopy, and experiments are described in which dynamical measurements of proton spin interactions are obtained. Finally, relaxation time e ffects of the observed force signal are considered in detail. A novel spin manipulation technique which is being implemented for future measurements is described in detail, and magnet con figurations for larger magnetic field gradients and consequently larger signal-to-noise ratio, are also described.
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    Force detected nuclear magnetic resonance on (NH₄)₂SO₄ and MgB₂
    (2009-12) Chia, Han-Jong; Markert, John T.; de Lozanne, Alex; Shih, Chih-Kang; Yao, Zhen; Shi, Li
    Nuclear magnetic resonance force microscopy (NMRFM) is a technique that combines aspects of scanning probe microscopy (SPM) and nuclear magnetic resonance (NMR) to obtain 3 dimensional nanoscale spatial resolution and perform spectroscopy. We describe the components of a helium-3 NMRFM probe and studies of ammonium sulfate ((NH₄)₂SO₄) and magnesium diboride (MgB₂). For our room temperature (NH₄)₂SO₄ studies we were able to perform a 1-D scan and perform nutation and spin echo experiments. In our 77 K MgB₂ we demonstrate a 1-D scan of a 30 micron powder sample. In addition, we describe magnetic measurements of the possible dilute semiconductors Mn[subscript x]Sc[subscript 1-x]N and Fe₀.₁Sc₀.₉N.