Outline Sample preparation Instrument setting Data acquisition Imaging software Spring 2009AFM Lab

Elements of a Basic Atomic force Microscope Spring 2009AFM Lab

Spring 2009AFM Lab Potential Diagram Distance Potential Repulsion Attraction

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 Spring 2009AFM Lab

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 Spring 2009AFM Lab

Camera and Lens Assembly Spring 2009AFM Lab

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) Spring 2009AFM Lab

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 Spring 2009AFM Lab

How to move and to maintain the probe at the right position? For a full scale of 1 micron assuming an image area of 1000 x 1000 pixel the x-y resolution is 1 nm No mechanical positioning can meet this specification Piezoelectric ceramic actuators can meet these requirements Spring 2009AFM Lab

Mounting the Nose Assembly on the Scanner Spring 2009AFM Lab 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. Spring 2009AFM Lab

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. Spring 2009AFM Lab

PicoView – Powerful SPM Control Software PicoScript – scripting interface for PicoView SPM I/O and control function library DLL (dynamically linked library) for VB, LabView, and more. Labview VI Allow interface with external acquisition cards Benefits Empower user to customize their own application needs No need to understand the source code structures Allows the popular LabView program to interface with PicoView Spring 2009AFM Lab

Data Acquisition: PicoView Software Spring 2009AFM Lab Data Types: Topography: “Z” height (quantitative information) Amplitude (AC AFM): rms value of the cantilever’s oscillation at the set frequency (qualitative info only) Phase (AC- AFM): Phase difference between driving signal and the waveform of the tip’s interaction with the sample Other types: Deflection, Current, Friction etc

Gwyddion Imaging Software Spring 2009AFM Lab Free powerful Imaging Software! recommended by Agilenthttp://gwyddion.net/

Image Metrology SPIP Imaging Software Spring 2009AFM Lab Expensive but very versatile!. Free trial. We have a license for one station at the time