Force Detection Using a Fiber-Optic Cantilever

A force measurement technique has been developed that utilizes a clamped fiber optic element both as a cantilever and as a highly sensitive probe of the static and dynamic displacement of a sample that is mounted near its free end. Light from a 1.5 mW superluminescent diode coupled into the fiber is used to detect displacement with 6*10/sup -13 m*Hz/sup -1/2 sensitivity for frequencies above 40 kHz. This technique has been used to study the interaction between macroscopic bodies with atomic sensitivity. Here, we report measurements of stiffness of junctions that form when two gold surfaces are brought into contact.Comment: 16 pages, 4 figure

High-Resolution Nanoscale Solid-State Nuclear Magnetic Resonance Spectroscopy

We present a new method for high-resolution nanoscale magnetic resonance imaging (nano-MRI) that combines the high spin sensitivity of nanowire-based magnetic resonance detection with high spectral resolution nuclear magnetic resonance (NMR) spectroscopy. By applying NMR pulses designed using optimal control theory, we demonstrate a factor of $500$ reduction of the proton spin resonance linewidth in a $(50\text{-nm})^{\text{3}}$ volume of polystyrene and image proton spins in one dimension with a spatial resolution below $2~\text{nm}$.Comment: Main text: 8 pages, 6 figures; supplementary information: 10 pages, 10 figure

Nanomechanical detection of nuclear magnetic resonance using a silicon nanowire oscillator

We report the use of a silicon nanowire mechanical oscillator as a low-temperature nuclear magnetic resonance force sensor to detect the statistical polarization of 1H spins in polystyrene. Under operating conditions, the nanowire experienced negligible surface-induced dissipation and exhibited a nearly thermally-limited force noise of 1.9 aN^2/Hz in the measurement quadrature. In order to couple the 1H spins to the nanowire oscillator, we have developed a new magnetic resonance force detection protocol which utilizes a nanoscale current-carrying wire to produce large time-dependent magnetic field gradients as well as the rf magnetic field.Comment: 14 pages, 5 figure