Ramp Parameter List

This parameter specifies which output you will ramp. To collect force plots, this parameter should be set to Z. For STM IV curves, select Bias.

This parameter defines the amplitude of the triangular waveform applied to the Z piezo. The units of this item are volts or nanometers, depending on the setting of the Units parameter. Regardless of the size of the scan, the entire scan is shown in the force curve; therefore, increasing the value of this parameter increases the horizontal axis scale on the force plot.

This parameter defines the maximum voltage applied to the Z electrodes of the piezo during force calibration operation. The triangular waveform shown below displaces the piezo up and down in relation to the value of Z scan start. Increasing the value of the Z scan start parameter moves the cantilever closer to the sample by extending the piezo tube. The units of this item are volts or nanometers, depending on the setting of the Units parameter. The initial value of Z scan start is equal to the average Z-center voltage defined by the feedback just prior to entering the Ramp Parameter List. Decreasing the value of this parameter shifts the force curve on the display to the right, while increasing the parameter shifts the curve to the left.

This parameter defines the rate that force plots are collected (typically ~1 Hz); that is, the rate at which the piezo completes an extension-retraction cycle (and therefore the rate at which new curves are displayed). The ramp size, forward velocity and reverse velocity determine the scan rate.

This parameter defines the piezo extension speed (to bring together the tip and sample).

This parameter defines the piezo retraction speed (to separate the tip and sample).

These parameters define the X and Y positions where the force plot will be collected, offset from the image center.

This parameter defines the number of data points captured during each extend and retract operation of the Z piezo during a ramp. This parameter does not affect the number of samples used in to collect image data.

The parameter defines the spring constantAmount of force required to bend a cantilever a specific amount (typical units are N/m). of the cantilever. The spring constant will be saved with captured force plots. The spring constant can be evaluated using the Thermal Tune method. Refer to the NanoScope V Controller Manual for details.

This item selects the units, either metric lengths or volts on the piezo, that define the parameters and the axes of the graph. Force may be displayed in nN of deflection force. This uses the spring constant. Changing this item in Ramp mode also changes it in the RealTime imaging mode.

This parameter defines the display as either Extend, Retract, or Both.

X Rotate allows you to move the tip in the X direction during ramping. This is useful because the cantilever is at an angle relative to the surface. X Rotate prevents the cantilever from plowing the surface laterally, typically along the X direction, while it indents in the sample surface (in the Z direction). Plowing occurs when the cantilever bends during indentation or with X movement caused by coupling of the Z and X axes of the piezo scanner. X Rotate moves the scanner in the opposite direction in which the cantilever points. Without X Rotate control, the tip moves in the direction of the cantilever during indentation. Normally, it is set to about 22.0 degrees. This parameter typically ranges between 12 and 25 degrees.