Quantitative analysis of dynamic-force-spectroscopy data on graphite(0001) in the contact and noncontact regimes

We present a comparative experimental and theoretical study of the frequency shift in ultrahigh vacuum dynamic force microscopy at 80 K on graphite(0001) measured as a function of the tip-sample distance for different resonance amplitudes A in the repulsive and attractive regime of the tip-sample Forces. The resulting frequency shift versus distance curves scale with 1/A(3/2) over the full range. We determined the tip-sample force from the frequency shift versus distance curves and found good agreement with specific force laws for long-range (van der Waals), short-range (Lennard-Jones), and contact (Hertz) forces.