qPlus magnetic force microscopy in frequency-modulation mode with millihertz resolution

• Maximilian Schneiderbauer,
• Daniel Wastl and
• Franz J. Giessibl

Beilstein J. Nanotechnol. 2012, 3, 174–178, doi:10.3762/bjnano.3.18

• , magnetically coated silicon cantilevers are used. These cantilevers are produced in large quantity by microfabrication techniques. Typical probe features are spring constants on the order of 10 Nm−1 and resonance frequencies of about 100 kHz. Another type of force sensor is made from a quartz (SiO2) tuning

• frequency noise is inversely proportional to the oscillation amplitude A of the force sensor. Thus, we can reduce frequency noise by using large amplitudes and therefore minimize the . Moreover, one achieves the best signal-to-noise ratio by using an amplitude that is on the order of the decay length of the

• magnetic dipole interactions, with a qPlus force sensor that is optimized to detect the strong force gradients of chemical bonds. Chemical bonds show force gradients up to about 100 Nm−1, while we have shown here that a sensor with a stiffness of 1800 Nm−1 can resolve force gradients from magnetic dipole

Oriented growth of porphyrin-based molecular wires on ionic crystals analysed by nc-AFM

• Thilo Glatzel,
• Lars Zimmerli,
• Shigeki Kawai,
• Ernst Meyer,
• Leslie-Anne Fendt and
• Francois Diederich

Beilstein J. Nanotechnol. 2011, 2, 34–39, doi:10.3762/bjnano.2.4

• maintaining a constant shift of the first flexural resonance frequency f1st with respect to the resonance far from the surface. Highly doped silicon cantilevers with integrated tips (Nanosensors, NCL), a typical resonance frequency f1st ≈ 160 kHz and a spring constant k ≈ 30 N/m were employed as a force

• sensor. The typical oscillation amplitude measures about A1st ≈ 5–20 nm. The cantilevers were annealed in UHV (30 min at 120 °C) and sputtered (1–2 min at 680 eV) with Ar+ ions for cleaning. In the experiments reported here, meso-(4-cyanophenyl)-substituted Zn(II) porphyrin (cyano-porphyrin, Figure 4