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Related Manuals for Nanosurf easyScan E-STM
Summary of Contents for Nanosurf easyScan E-STM
- Page 1 Operating Instructions easyScan E-STM Version 2.1...
- Page 2 ‘N ’ ANOSURF AND THE ANOSURF OGO ARE TRADEMARKS OF ANOSURF REGISTERED AND OTHERWISE PROTECTED IN VARIOUS COUNTRIES © J 2004 AG, S .:BT00655, ANUARY ANOSURF WITZERLAND...
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Page 3: Table Of Contents
Table of Contents Introduction What is STM? ..................4 Scanning with the E-STM ..............5 (Un)packing and Installation Unpacking the instrument ..............8 Hardware Installation ................9 Software installation ................11 System requirements Installation Procedure Simulated microscope Preparing for Measurement Preparing and installing the STM tip .......... -
Page 4: Introduction
Introduction This manual gives instructions on how to set up and use your Nanosurf easyScan E-STM system. The aim is to help people who don’t have a good knowledge of physics to get pictures of atomic resolution easily. This intro- duction chapter gives some general information on the scanning tunneling microscopy technique, and its implementation in the easyScan STM. -
Page 5: Scanning With The E-Stm
E-STM CANNING WITH THE NTRODUCTION To be able to get such excellent pictures of atomic resolution is almost in- credible, considering that the size of the atom in relation to the tip, is that of a golf ball to a mountain! Scanning with the E-STM In the E-STM, a platinum-iridium tip is moved in three dimensions using piezo-crystal translators that are driven with sub-nanometer precision. - Page 6 E-STM NTRODUCTION CANNING WITH THE The sample to be examined approaches the tip within a distance of 1 nano- meter (1nm= 1 / 1 000 000 000 m). Classical physics would prohibit the appearance of electrons in the small gap between a tip and a sample, but if a sharp tip and a conducting surface are put under a low voltage (U~0.1V) a very small tunneling current (I~1nA) may nevertheless flow between tip and sample.
- Page 7 However, this mode only works when the sample is atomi- cally flat, because the tip would otherwise ‘crash’ in to the sample What is so special about the Nanosurf easyScan E-STM? The E-STM was designed to allow people without training as a physicist to do experiments in the world of atoms.
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Page 8: (Un)Packing And Installation
NSTALLATION NPACKING THE INSTRUMENT (Un)packing and Installation This chapter describes the installation of the Nanosurf easyScan E-STM. Important! To enable measurements of atomic resolution to be made the following precautions must be taken to keep equipment dust and grease free: •... -
Page 9: Hardware Installation
ARDWARE NSTALLATION PACKING AND NSTALLATION 1 - easyScan E-SPM electronics 2 - STM scan head 3 - Power supply LPS-1 4 - RS232 cable between computer and control electronics 5 - Mains cable 6 - Vibration isolation platform 7 - Magnifying cover with 10x magnifier 8 - Tool set, containing a: wire cutter b: half-round pliers, c: pointed tweez- ers, d: rounded tweezers, e: 30 cm Pt/Ir 0.25mm wire for tips, f: sample holder, g: sample set: HOPG (graphite), gold thin film, three empty... - Page 10 PACKING AND NSTALLATION ARDWARE NSTALLATION Choose a steady table where you can work undisturbed. To ensure the fault- less operation of the STM it has to be kept away from vibrations, heat emission and air current. - Put the STM scan head (2) onto the vibration isolation platform (6). Fix the scan head cable under the strain relief clip.
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Page 11: Software Installation
• 8 MB RAM or more (16 MB recommended) • graphics adapter with 800 x 600 resolution and 16-bit colours (‘high color’) or better (resolution of 1024 x 768 recommended) * The Nanosurf ‘USB Adapter: ES’ option must be acquired to use the USB port. Installation Procedure - Turn on your computer and start Windows. - Page 12 PACKING AND NSTALLATION OFTWARE INSTALLATION - Select the button ‘Install’, to install the data acquisition program ‘easy- Scan’ on your computer. Setup will ask for the directory in which the program files are to be copied: - Put them in the proposed directory, unless the ‘Program Files’ directory has a different name in your language of the Windows operating system.
- Page 13 OFTWARE INSTALLATION PACKING AND NSTALLATION - Accept the proposed name by clicking ‘OK’ or type another name. The installation setup will now ask for the ’COM-Port’: - Select the serial port to which you have connected the E-SPM electronics (See section hardware installation, figure components, 1) The setup program will start copying files onto your hard-disk.
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Page 14: Simulated Microscope
PACKING AND NSTALLATION OFTWARE INSTALLATION Simulated microscope You can start the easyScan software without having the microscope con- nected to your computer. We recommend using this simulation to explore the easyScan-system (measurements and software) ‘off-line’. When the simulate microscope mode is started, the following dialog box appears: By clicking ‘Start Simulation’... -
Page 15: Preparing For Measurement
REPARING AND INSTALLING THE REPARING FOR EASUREMENT Preparing for Measurement The easyScan hard- and software have been set up according to the instruc- tions in the section (Un)packing and Installation. Preparing and installing the STM tip The STM tip can be prepared and installed by yourself. This is the most difficult part of your preparations. - Page 16 REPARING FOR EASUREMENT REPARING AND INSTALLING THE - Hold the tip wire with the tweezers behind the freshly cut tip. Important! • Do not touch the end of the tip with anything. • Take care that the tip wire is straight. •...
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Page 17: Preparing The Sample
REPARING THE SAMPLE REPARING FOR EASUREMENT Double clamp Always use the following procedure for mounting the tip under the double clamp (see figure mounting the tip under the double clamp). Using a different procedure may cause a gradual deterioration of the measurement quality due to loosening of the clamp. - Page 18 REPARING FOR EASUREMENT REPARING THE SAMPLE Gold thin film Cleaning the sample is neither possible nor necessary. Never touch the sam- ple with your fingers or put it upside down anywhere, this will only make it unusable faster. Graphite The surface of the graphite sample can be cleaned when it is very dirty or uneven.
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Page 19: Installing The Sample
NSTALLING THE SAMPLE REPARING FOR EASUREMENT Installing the sample Important! Always store the sample holder in its package, in order to prevent corrosion (see chapter Maintenance). - Unpack the sample holder (figure components, 8 f) touching only its black plastic handle. - Put the prepared sample onto the magnetic end of the sample holder using a pair of tweezers. -
Page 20: First Measurements
IRST EASUREMENTS TARTING THE MICROSCOPE First Measurements All the preparations are now done: The STM is assembled, the software and a tip are installed and the graphite sample is ready. In this chapter step by step instructions are given on how to operate the microscope and get your first pictures. -
Page 21: Approaching The Tip
IRST EASUREMENTS PPROACHING THE TIP Approaching the tip To start measuring, the sample must be very close to the tip to enable a tunneling current to flow. Approaching the sample without touching the tip, is a delicate operation carried out in three steps. The LED on the scan head tells you about the distance between the tip and the sample: LED orange: z-piezo fully extended toward the sample: the distance... -
Page 22: Fine Approach By Piezo Motor
IRST EASUREMENTS PPROACHING THE TIP - If necessary try turning the sample holder around its axis so that the tip points towards a mirror-like area of the sample. - Put the magnifying cover (7) over the scan head without touching the sample holder, place the magnifier so, that you can see the mirror image of the tip in the sample. -
Page 23: Automatic Approach
IRST EASUREMENTS PPROACHING THE TIP - Open the ‘Feedback Panel’ in the menu ‘Panels’. - Ensure that the following parameters are set correctly: • the ‘SetPoint’ (tunneling current) on approx. 1.00nA, • the ‘GapVoltage’ (tip-sample-voltage) on 0.05V, • the ‘P-Gain’ on 12 and the ‘I-Gain’ on 13 (feedback loop param- eters). -
Page 24: Start Measurement
IRST EASUREMENTS TART MEASUREMENT The sample holder is now moved towards the tip with the help of the piezo motor, until the tunneling current entered under ‘SetPoint’ is detected. Now the distance between sample and tip is controlled by the feedback loop. If the approach was successful, the LED on the scan head changes from or- ange to green and the message box ‘Approach done’... -
Page 25: Adjusting The Sample's Tilt Coordinates
’ IRST EASUREMENTS DJUSTING THE SAMPLE S TILT COORDINATES Starting picture: left: a good LineView, right: a ‘nervous’ LineView If the line in the ‘LineView’ is calm and reproduces consistently, you can continue with the next section. Adjusting the sample’s tilt coordinates Ideally, the plane of the measurement and the sample's surface should lie in the x-y-plane of the scanner. - Page 26 ’ IRST EASUREMENTS DJUSTING THE SAMPLE S TILT COORDINATES This slope depends on the fast scan direction and therefore on the rotation of the measurement, as shown in figure Tilt, position A and B. It is desirable that the measurement plane is parallel to the sample plane, because this makes it easier to see smaller details in the measurement, and because the z- feedback loop can function more accurately in this case.
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Page 27: Achieving Atomic Resolution
IRST EASUREMENTS CHIEVING ATOMIC RESOLUTION - If the scan line is not horizontal, alter the value for ‘Y-slope’ until the y- axis of the scan lies parallel to the y-axis of the sample. - Reset the ‘Rotation’ to 0°. The ‘LineView’ shows the X-slope again. The value of the ‘Z-Offset’... - Page 28 IRST EASUREMENTS CHIEVING ATOMIC RESOLUTION - click : The mouse pointer becomes a cross and the ‘Tool Info Panel’ opens. - look for a ‘flat’ region (similar grey values) in ‘TopView’ and make a square there with the mouse pointer. The size of the square is dis- played in the ‘Tool Info Panel’.
- Page 29 IRST EASUREMENTS CHIEVING ATOMIC RESOLUTION 4. Some parts of the scan head react to the slightest temperature changes. As these thermal ‘movements’ influence the measurements on the nanometer scale, the sample has to be scanned as fast as possible. - Set the ‘Time/Line’ in the ‘ScanPanel’ to 0.06s for atomic resolution. View Panel - If the contrast in the ‘Top View window is too large, or too small, open the ‘View Panel’...
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Page 30: Snapshots Of Images
IRST EASUREMENTS NAPSHOTS OF IMAGES Snapshots of images When you are satisfied with your image and would like to keep it, you can take a snapshot and save it for later: - During the measurement, you can select in the ‘ScanPanel’. After having completed the actual frame, a copy of the measured image is taken and displayed in a separate window behind the ‘ScanPanel’. -
Page 31: Judging The Quality Of The Images
IRST EASUREMENTS UDGING THE QUALITY OF THE IMAGES - set P-Gain to 0 and I-Gain to 2 in ‘Feedback Panel’. - apply these new values by using - to visualize the current information, choose ‘Current’ as input in the ‘View Panel’. Notice that ‘Z-Range’... - Page 32 IRST EASUREMENTS UDGING THE QUALITY OF THE IMAGES • If, during a good measurement the image quality diminished dramati- cally, the tip has most probably picked up some particles or you are near a step in the surface. - See Problems and solutions: Image quality suddenly deteriorates’ In the following cases the tip has to be replaced i.e.
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Page 33: The Graphite Surface
IRST EASUREMENTS HE GRAPHITE SURFACE • If each image looks different: • If the scan lines in ‘LineView’ are unstable and the image in the ‘TopView’ is not ‘sharp’: The graphite surface In a good top view image of graphite you will see a pattern consisting of white, grey and black spots. -
Page 34: Measuring Gold
IRST EASUREMENTS EASURING 0.34nm 0.14nm 0.25nm Graphite surface: left: measurement; right: lattice model This also causes the lattice constant between the bright ‘hills’ to have the higher than normal value of 0.25nm. Measuring Gold It is more difficult to obtain good images of a gold. Atomic structures are difficult to observe because the electrons on the surface are much more homogeneously distributed unlike graphite. - Page 35 IRST EASUREMENTS EASURING Due to the fact that the gold sample cannot be cleaned by simple means it is possible that with time contaminants may prevent you obtaining good re- sults. Tip: Before you do any experiments with the gold sample it is necessary to prac- tise on the graphite sample.
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Page 36: Finish Measuring
IRST EASUREMENTS INISH MEASURING Finish measuring - To stop a measurement, click - By clicking , and then clicking in ‘Approach Panel’ you can retract the sample holder to a safe and visible distance from the tip. - Close all panels in order to see the saved ‘snapshots’. - Activate the ‘snapshot’... - Page 37 IRST EASUREMENTS INISH MEASURING - Store the sample holder in its container, and check that the silica is still blue (see chapter maintenance) By storing the instrument in the suitcase it is protected from dust. Simulta- neously the rubber feet of the vibration isolation platform should be re- lieved.
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Page 38: Maintenance
AINTENANCE Maintenance To ensure the fault-free operation of the microscope the following instruc- tions for maintenance have to be followed. Scan head It is very important to prevent the sample holder and the open part of the scanner from becoming dirty or damp. •... -
Page 39: Scan Electronics
AINTENANCE • Clean the sample holder guide bars (see picture above), the surfaces of the piezo motor and the tip holder with a cotton swab if necessary lightly moistened with alcohol, ensure the tip is removed when doing this! Scan electronics Clean the cabinet and the controls with a soft cloth lightly moistened with a mild detergent solution. -
Page 40: Problems And Solutions
ROBLEMS AND OLUTIONS Problems and Solutions ‘No connection to microscope!’ This error message appears when the scanning software is waiting for an answer from scan electronics. This can have various reasons: • The microscope is not connected: - If you wish to perform a simulated measurement select Otherwise check the connection and select •... - Page 41 ROBLEMS AND OLUTIONS • The electronics is damaged. - Contact your dealer. Sample holder moves too slowly / stops sometimes If the fine approach using is affected: - Clean the sample holder, guide bars and the surfaces of the approach motor following the procedure described in chapter Maintenance.
- Page 42 ROBLEMS AND OLUTIONS Image quality suddenly deteriorates • When a scan line suddenly starts reproducing badly, the tip may have picked up some particles, or it is scanning close to a deformity in the sample's surface. - Continue measuring for a while (4-5 images) eventually the tip loses the picked up material again.
- Page 43 ROBLEMS AND OLUTIONS - Retract the sample holder first by using then . Remove the sample holder by hand. - Pull the tip out from under the tip holders carefully, using a pair of sharp tweezers. - Carefully follow the instructions in chapter ‘Preparing and installing the tip’.
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Page 44: Technical Data
ECHNICAL Technical Data The specifications given here are typical values of the Nanosurf products. The exact specifications vary somewhat from instrument to instrument, and are stored on the installation CD, and can be found in the Calibration dialog (see Software Reference). - Page 45 ECHNICAL...
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