User`s guide

AC Modes 6
Agilent 5500 SPM User’s Guide 110
response to amplitude changes. This lack of feedback reduces signal
noise, enabling high resolution imaging of very flat samples.
The change in amplitude as the tip scans across the sample is mapped as
Amplitude and displayed in volts in the Image buffer.
Magnetic AC (MAC) Mode
In Magnetic AC (MAC) Mode AFM, a cantilever coated in magnetic
material is driven by a coil-generated oscillating magnetic field. The
Lock-in in the MAC controller precisely determines and maintains
oscillation amplitude and phase relation changes.
In AAC Mode, the oscillator in the nose assembly oscillates the entire
system, including liquid if imaging in liquid. In MAC mode, because
the oscillation is driven by a magnetic field, only the
magnetically-coated tip oscillates, providing a sharper resonance peak,
and therefore higher resolution imaging. MAC Mode is the most
accurate AC technique available, particularly for imaging in liquids.
MAC Mode requires either a MAC or MAC III controller, both of which
offer the lock-in amplifier required to precisely drive the MAC coil (the