27-12-2012, 05:21 PM
AFM Fundamental System Components
AFM Fundamental System.ppt (Size: 1.89 MB / Downloads: 35)
Sample Preparation
AFM Does require minimum of sample preparation:
No clean room handling
No thin film metal coating
Works in liquids, gases, and vacuum
Works at elevated or sub ambient temperatures
Dimensions are not critical
Instrument Setting
Sample: Center it in the middle of the sample plate and immobilize it using dual side sticky pads
Laser: Laser beam has to bounce on the tip of the cantilever.
Photodiode: Reflected beam signal has to be shared equally between the 4 cells
System adjustment: Servo Gain (PI values), Force, Raster speed
Video System Overview
The NAVITAR zoom lens system provides an optical magnification range of 2.1x-13.5x to the camera.
The degree of magnification at the monitor depends on the ratio of the monitor size to the CCD chip size. The camera uses a 1/3" CCD (6mm diagonal). Using a 12" monitor (305mm diagonal) with the 1/3" CCD chip, the total magnification of the system would then be (13.5) x (1.8) x (305/6) ≈ 1230 (1 micron would be seen as 1.2 mm on the screen)
How the sample is scanned
Positioning the probe
The main challenge is to move the probe with increments as small as 0.05 nm and keep it at the right position
Resolution in the X-Y range is limited by the radius of the probe ~ tens nm
Resolution in the Z-range is limited by the noise of the system ~0.05 nm
Introduction to Piezoelectric materials
Ceramic tube
Pendulum design
Mounting the Nose Assembly on the Scanner
Push evenly and straight down when inserting the nose assembly. Small off-axis forces will create LARGE torques about the anchor point for the piezoes, where most breakage occurs. Do NOT push as this will damage the spring clip and/or glass down on the top of the nose assembly window.
Controlling and Imaging Software
PicoView provides control and the first line of visual interpretation and has to be understood before getting any further. It gives limited information about results and requires the use of a more sophisticated software to interpret the experiments.
Gwyddion and Imaging Metrology provide sample measurements and statistical data. They have to be used to prepare professional reports.
PicoView – Powerful SPM Control Software
Benefits
Simultaneous real-time display of up to eight channels (in all resolutions)
Simultaneously display real-time image and post-processed data
Unlimited data points in spectroscopy
16x16 to 4096x4096 pixels in images
Parametric data structure in Spectroscopy
Allow flexible data presentation
Temporal display of all channels
Select any channel as x-axis and plot all the rest against it.