SPM user manual

Dear friend, Thank you very much for selecting Nanotec Electronica SPM products. The Nanotec team hope that you will enjoy them, and it will cover all your needs for SPM measurements. In the following pages, you will find usage instructions for the different parts of the system. Please read them carefully, paying special attention to the safety recommendations included for optimal results with the system. Also, you will find with your system a WSxM 2.0 software manual with explanations about the different software possibilities. Please note that in http://www.nanotec.es, you have the possibility of subscribing to NanotecForum, a discussion forum to which all Nanotec Electronica SPM products’ users are welcomed. Best regards, The Nanotec Electronica Team Parque Cientifico de Madrid. Pabellon C, campus UAM. Cantoblanco E-28049 Madrid SPAIN Phone number: +34-914 973 436 Fax: +34-914 973 437 e-Mail: nanotec@nanotec.es

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Atomic force microscope image of a multiwall nanotube circuit. Image size 15µmx15µm From Pedro J. De Pablo and Ron Reifenberger, Physics Department,

Purdue University USA.

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Manual Index Dulcinea electronics Description.........................................................................................................p.4. Safety instructions..............................................................................................p.6. Installation instructions......................................................................................p.6. Using the electronics..........................................................................................p.7. AFM mechanics Description.........................................................................................................p.8. Installation instructions....................................................................................p.13. Safety instructions............................................................................................p.18. Optical microscope Description.......................................................................................................p.19. Installation instructions....................................................................................p.20. Safety instructions............................................................................................p.26. Using the optical microscope...........................................................................p.26.

Atomic force microscope images of a DNA molecule partially covered with gold. The right image shows a modification introduced by the AFM tip. From LNM.

Departmento Física de la Materia Condensada UAM.

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Dulcinea electronics

1. Description

The Dulcinea electronics is an electronics system specifically designed to drive SPM equipments. While its more immediate application is for the control of Nanotec Electronica SPM systems, it is designed in an open and modular way in order to facilitate the interfacing with any other AFM/SNOM/STM system. Dulcinea Front View

- Graphic display: It is used for notifying the user about events like the start/end of the communication with the computer and the gains changes. It is also opened for future ampliations.

- Z-Manual: 10 turns adjustable potenciometer (Software configuration): This potenciometer can be used for manually adjusting the Z Offset applied to the piezo. For its use, it needs first to be enabled by software using WSxM (selection available in the Control Menu). It is important to remember to only enable/disable it moving it previously to the intermediate (50) position. The maximum offset you can apply is +/-50V.

- Z-Manual: LED active Indicator: This LED will be on when the manual offset is active.

- Z Secure lamp push switch: At any moment you can press this button for generating an offset voltage of +150V to the Z piezo voltage. This allows fast withdrawal of the tip from the sample without using the software.

- BNC connectors for signals monitoring (A, B, C, D): Software configurable BNC monitors. Using the Scanning/Dulcinea outputs menu in WSxM software you can select the signal to monitor from a number of them. Please note that A and B BNCs have a low pass filter of 50KHz while C and D have a low pass filter of 800KHz.

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Dulcinea back view

- BNC connectors: target specific BNC monitors and BNCs for external inputs: o AC Mode BNCs (only useful when Dynamic Force Board is installed):

VCO Out: Driving signal for cantilever oscillation (+/-10V). PID Out: Phase Lock Loop (PLL) output (only useful when PLL

has been activated in WSxM software). I. Out: Driving signal for magnetic cantilever oscillation. It is an

AC current source with the same frequency as the VCO Out (selected in the WSxM tapping menu).

Ext. In: [Input signal]. Allows to enter an external signal as the dynamic mode reference signal (+/- 10V).

o General use BNCs Sum: Output sum of the four photodiode quadrants. Z Mod: [Input signal]. Allows to enter a modulation voltage to

be applied to the Z Voltage to the piezo. It has an allowed input range of +/-10V. The maximum input frequency allowed is 10KHz.

Bias Mod: [Input signal]. Allows to enter a modulation voltage to be applied to the Bias Voltage between the tip and the sample. It has an allowed range of +/-10V. The maximum input frequency allowed is 10KHz.

- IDC50 Connectors-P: IDC50 male connectors for low voltage communication

with the SPM head and the Digital Signal Processor (DSP): o To Head: Connector with the low voltage (+/-10 V) signals that go to

the SPM head. In Nanotec Electronica systems, you will have to connect here the cable labelled “To Head”

o From DSP Analog: Connector with the low voltage (+/-10V) analog signals coming from the DSP. You will have to connect here the multi-colour cable labelled “From DSP Analog”

o From DSP Digital: Connector with TTL control signals coming from the DSP. You will have to connect here the gray cable labeled “From DSP Digital”

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- IDC20 Connector-P Digital In/Out: IDC20 male connector with user available

digital signals. It gives trigger signals (configurable by software in the WSxM View/Digital Signals menu) and it receives digital inputs from the Nanotec Electronica counter electronics.

- BNC Connectors

o In: ADC Auxiliary channels: Four input channels (8,7,6,5) are available for the user in order to introduce any low voltage (+/-10V) signals. These signals will automatically be measured by WSxM software, and they will be acquired synchronous with the scan generation, allowing you to map this signal respect to the piezo scan. You can view and save these signals by selecting the channel in the Viewer Options menu of the WSxM software.

o Out: DAC Auxiliary channels: Three output channels (12,13,14) are available for the user in BNCs. You can use these channels to output a feedback for your custom feedback system.

o VCO Monitor: Only useful when the Dynamic Force Board is installed, this monitor BNC will allow you to visualize the voltage that, coming from the DSP board, controls the frequency modulation in the 3dModes Frequency/Z or in the digital PLL working mode.

- HV Connector: In this connector you can find all the high voltage (usually +/-

150V) outputs coming out from the Dulcinea electronics. - RS-232 DB9 connector-P: Serial connection with the computer.

- Power 90 / 240 V AC 50/60Hz. Fuse 2A: Power supply input. Compatible with

power supplies from 90V to 240V (including American 110V and European 220V) and AC frequencies of 50 to 60 Hz (Universal power supply), it comes with a 2Amperes fuse for shortcircuit prevention and there is also a replacement 2A fuse included in the same place.

2. Safety instructions - Never touch the High Voltage part of the electronics with the unit powered on. It

has dangerous voltages that can cause severe damage including death. - When powering off the electronics, please take care of waiting a minimum of 30

seconds before powering it on again. - Keep the electronics away from water. - Keep the electronics away from electromagnetic radiation sources. - Never open the electronics unit without the previous agreement of the

manufacturers. - Never change the fuses for a different type. 3. Installation instructions

In your Dulcinea-based system, you need the following items in order to work properly:

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- Dulcinea electronics - Computer system (CPU, screen, keyboard and mouse) with preinstalled

Digital Signal Processor (DSP)* - RS-232 Serial cable

* : Please notice that your computer has a DSP installed if two flat cables (IDC50) are coming out from its rear panel. Before starting the installation, please make sure that you have all the needed components and that both the electronics and the computer have the power supply cable unplugged. The RS-232 cable communicates the computer with the Dulcinea electronics. It is needed for WSxM to recognize that Dulcinea electronics is installed. Connect this cable from COM1 or COM2 serial port in the computer to the Dulcinea rear panel RS 232 connector. The cables labeled “From DSP analog” (multi-color) and “From DSP digital” (gray) going out from the computer carry real time signals fundamental for the proper working of the electronics. You should connect “From DSP analog” cable to the “From DSP analog” connector in the Dulcinea back and “From DSP digital” cable to the “From DSP digital” connector. Finally, you should connect the “To Head” and “To Head HV” connectors to your SPM head (or to any extra intermediate electronics) using the cable/s for this purpose. Now you can power on the electronics and the computer and start WSxM software to control it. 4. Using the electronics

Dulcinea electronics features are mainly controlled by WSxM software. For using them the first step will be to start WSxM software (WSxM 3.0 or later required); when starting the Data Acquisition part of the software (File/Acquisition, Acquisition/Start), WSxM will recognize that the Dulcinea electronics is connected and will show some serial number and software version information. Dulcinea electronics will also respond to this communication changing the messages in the screen.

If the Secure button is pressed, WSxM software will detect it and prevent you

from beginning the Data Acquisition before unpressing the Secure button. This button is generating an extra offset to the Z piezo voltage that will not allow you to work properly.

With the acquisition started, you can use the button besides the Z Off parameter

(Z Offset) in the Control menu to enable manual handling of the Z Offset to the piezo, and you can use the Scanning/Dulcinea outputs menu for selecting the signals you want to monitor. Also you can use the View/Digital Signals menu for selecting the different trigger options or the use of specific digitally-driven electronics.

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AFM mechanics 1. Description

The Nanotec AFM mechanical system can be divided into two main different parts, the chassis and the head. In the next images it is shown a general view of the different elements that integrate the mechanics you have received, pointing out their different components:

Parking Piezo scanner

Motor base

Micrometric screws to move the optical table

Security brakes to fix the optical table while transporting it

Fig.1.1 Chassis

Optical table Sorbothane balls

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Micrometric motor-approach screw

Sample holder

Micrommanuascrews

Fig.1.2 Chassis

DB37 connectorfrom Dulcinea

To Head

LEMO femaleconnector for the head

Retaining springs

To Head HV

Security brakesto fix the opticaltable while

etric l-approach

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r

Scadph

Micrometric screws for fine adjustment of the photodiode

Fig.2.1 Head

Photodiode

Motor base

Fig.2.2 Head. Detail of the SFM head showing the laser p

Lase

Photodiode

Optical cubes

Micrometric screws for laser alignment on the cantilever

rews for coarse justment of the otodiode

LEMO male connector

Cantilever holder

Cantilever

ath through the optical system (in red)

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Fig.2.3 Piezo scanners (long and short)

Fig.2.4 Cantilever holder

With the system it is also provided a glass cover which allows covering all the system to protect from acoustic and environmental noises, as well as to perform an atmosphere control.

Fig.2.5 Glass cover

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Metallic base and fork to easy placing/removing cantilever when using rubber to fix it to the cantilever holder.

Fig.2.6 Cantilever exchange bay Other elements you have received which are not shown in the images are the next ones:

• Metallic cover for the chassis (you will see it in Fig.6.1)

• Standard cantilevers to start working

• Silver paint and scalpel to fix and remove the cantilever on/from the cantilever

holder.

• Rubber subjections for cantilever fixing

• Computer with DSP inside and screen. CD with WSxM software and DSP drivers (already installed)

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2. Installation instructions

When receiving your AFM system, you will get the chassis in a similar situation as shown in figure 1.1, except the position of the sorbothane balls and the position of the piezo scanner. Take the sorbothane balls and place them under the chassis as shown in Fig.1.1.

If you have an optical table, once you have placed the chassis where you want in your laboratory, slacken the optical table brakes, in order to be able to move the optical table with the micrometric screws placed to this end.

About the piezo scanner, since the piezo is one of the most fragile parts of the system, it is packed separately from the rest of the chassis, and you will have to place it in its position. To do that, follow the next diagram:

Grooved brass screws

Piezo scanner

Fig.3 Piezo scanner assembly

• The grooved brass screws are already placed in their final position, in the motor base, so you will find them there. You have to fix the piezo scanner to the motor base with them, but you do not have to screw them very strongly, just stop when you realize they are getting to the end in order not to damage the piezo.

• Connect the piezo scanner to the chassis through the LEMO connectors (see Fig. 3), making sure that you place together the red points in each of them and that you hear a “click” when doing it. The high voltage signal for the piezo scanner is supplied through this connector.

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Next step to check that the motor is properly connected (see Fig. 4):

Fig.4 Motor connection

• Make sure you connect the MOLEX connector as shown in Fig. 4. In case it

is connected in the opposite way the motor will approach when you want to withdraw and vice versa.

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Now it is time to place the head. To do that, follow the next diagram:

Fig.5 AFM head assembly

• You have to place the head on the three micrometer screws at the motor

base, matching them with the appropiate holes in the head (see Fig.5). You can also place the the head at the parking (see Fig.1.1).

• Connect the head to the chassis through the LEMO connectors (see Fig. 5), making sure that you place together the red points in each of them and that you hear a “click” when doing it.

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At this point, once you have assembled all the mechanical components among themselves, you have to connect the mechanical system to Dulcinea.

Metallic cover

Fig.6.1 Dulcinea connection

Fig.6.2 Dulcinea conn the DB37 connector and

Fig.6.3 Dulcine

DB37

ection. Detail in Fig. 1.2 showing the cables coming from Dulcinea

To Head

To Head HV

a connection. Dulcinea back view

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Now you have to fix a cantilever on the cantilever holder. Once you have done it, you can place the cantilever holder in the head, as shown in the next image.

Fig.7 Cantilever holder in the head

• Finally, once you have connected properly all the AFM system (computer, Dulcinea and mechanics), you can check that everything is right connected and working fine by switching on the system, running WSxM, turning on/off the laser in the Photodiode Menu and moving the motor up and down with the comands withdraw/approach in the Approach Menu.

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3. Safety instructions

• If you have an optical table, remember to slacken the optical table brakes, in order to be able to move the optical table with the micrometric screws placed to this end.

• Be very careful while placing (or changing) the piezoelectric scanner. It is one of the most fragile parts of the system.

• Never try to dissassemble any mechanical or electronical component of the system without previous authorization from the manufacturer or authorized representative.

• The micrometric motor-approach screw in the chassis (see Fig. 1.2) can also be moved by hand, pushing down the motor. If you move it in this way, make sure that after the movement the white, plastic coupling piece is perfectly coupled, because if not, the micrometer screw will not move with the motor.

• While handling the AFM head, do it taking it as shown in the next figure:

Fig.8. Handling the AFM head Do not touch the optical parts in the AFM head (optical cubes, laser, photodiode…). Take special care not to touch the laser or its cable, you could disadjust it.

• If you use silver paint to fix the cantilever to the cantilever holder, do not use liquids to clean the rests of silver paint from the holder. Particles of silver paint could get between the different parts of the holder producing undesired electrical contacts.

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Optical microscope

1. Description

The optical microscope that Nanotec provides with the AFM system can be divided into four different parts. It is shown in the next image:

Optical Microscope Stand

Light source (optical fiber)

Fig. 1 Optical Microscope

Optics

Camera

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2. Installation instructions

First of all, it is necessary to assemble the optical microscope stand. It is given a diagram showing the different parts of it. We will follow that diagram to explain the steps of the assembly (See figure 2).

3.b Grey prismManual screw

3.a Arm

3.cLeg

Base

Allen screws

Fig. 2 Optical microscope stand diagram

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• Fix the column of the stand (metallic cylinder we will call “leg”, part 3 in the diagram) to the base of the stand (part 2) using the three allen screws (parts 1) and their respectives pressure washers. It is recomendable to do it just with the base and the leg, removing the two parts coming with the leg, and replacing them once the screws are well fixed.

• Place the “arm” of the stand, (the long, black cylinder part 3.a), into the orifice of the grey prism part that comes with the leg (part 3.b). This prism is fixed to the leg by means of one of the two manual screws with an X black holder that come separately. This screw is the one that enables the horizontal movement of the optical microscope when it comes to place/remove it over the AFM head. For that, make sure the part that supports the prism at the leg (black cylindrical part with a manual screw, part 3.c) is very well fixed, because it is the part that supports all the weight of the optical microscope. The other manual screw with an X black holder is used to fix the arm to the grey prism. It is recomendable to fix it from the middle of the arm to the side where there will be the optics, in order to get all the system well balanced (as it is in Fig. 1).

• At the end of the arm, unscrew the part called part 7 in the diagram, with its washer (part 6) and place the final part of the stand (part 5), screwing parts 6 and 7 after that to their initial position. Place the optics (part 4 in the diagram) into part 5 of the stand, leaving the conexion for the optical fibre on the right side.

• Connect the light source with the optical microscope by means of the optical fibre, leaving the light source and the AFM chasis on different tables (usually the AFM chassis on an anti-vibration table).

• You will receive the digital camera placed on the top of the optics. You can change its orientation slackening the coupling part (the one on the top of the optics, fixed with three allen screws). Plug the camera into an USB port in the CPU. The software is already installed; anyway, the CD with the drivers and the software is provided. Here we show the principal sections of the software. You have to click on the shortcut

Fig.3.1 Shortcut

you have in the computer.

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After that, in the next screen, it will appear:

Click here to start the digital camera video visualization

Fig. 3.2

Then, the live video will start, and you will see the next options:

Resolution while live video

Captured photo resolution

If you check this box, the software will save the images with a default name in a default folder

Photo capture Video capture

Fig.3.3 Live video

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If you click the “Settings” icon:

Fig.3.4 Settings

You have to click in and then select (see Fig. 3.2). It will appear the next menu:

Here you can select the default directory to store files, where images will be saved if you check the box ‘Save automatically’ (see Fig. 3.3). You have to select the destination and create there a new album (see next image, Fig.3.5)

Fig.3.5.1 Add Album

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The other possibility is to select “Use an existing folder as album”:

Fig.3.5.2 Add Album Then you can select the folder you want to save your files in. Finally, if you click, (see Fig. 3.3) it will appear:

In this menu you can change all the usual camera control parameters (brightness, contrast,…) in order to improve the image which is being given by the digital camera

Fig.3.6 Properties

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Fig. 4 Example of a complete system configuration IMPORTANT

• Nanotec AFM system is designed in order to place the optical stand behind the chasis, placing the optical microscope above the AFM head moving the optical arm from the right. That is why it is advisable to plug the optical fiber coming out from the right, in order not to have anything above the AFM head when the optical microscope is removed, being possible to place the glass cover while using the AFM system. In this way, it is advisable to place the CPU and the electronics to the right of the AFM and the optic systems.

• The light source induces mechanical vibration, that is why it is very important not to place it on the same table as the AFM chasis and head.

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3. Safety instructions

• When operating with the optical microscope, you should have to fix and unfix manual screws, in order to move it and place it in the right position above the optical cube of the AFM head. While you are getting used to the optical system, when fixing and unfixing screws, do it clearly separated from the AFM system, to avoid damaging it if you unfix the wrong screws.

• When installing and operating with the optical system, make sure it does not touch any part of the AFM head, placing it in the way the optical microscope could be moved/removed above the head properly. Also take care about this, while looking for the optimum focus position to have the best image as possible. Take special care that any part of the optical microscope do not touch the laser or its cable, as it could disadjust it. 4. Using the optical microscope

• Once the optical microscope is installed, the first thing you have to do to operate with it is to turn on the light source and to start the software of the digital camera in the CPU.

• Then, you have to place the optical microscope objective above the optic cube of the AFM head.

• Probably you will not see anything at the first trial. You have to look for the right vertical distance between the optical microscope and the AFM head, in order to have the sample in its focus. It is usually around 2-3 cm above the head. You also will have to take into account the zoom of the microscope. It is advisable to begin with the lowest zoom as possible, and then, once you have an image, change it if it is necessary (See figure 5).

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USB cable

Camera

Zoom

Focus Fine Adjustment

Fig. 5 Optics in the optical micros

Optical Fiber

cope

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The other important fact is the amount of light the source is giving, probably you will have to change it at the light source to have enough light (if the image is too dark) or to have no saturation (if the image is too bright). It is useful not to have the optics totally vertical. Instead of that, you can try to place it in a similar way as shown in the next picture:

Laser

AFM head

Fig. 6 It is advisable not to place the optics completely parallel

Optics

to the laser of the AFM head

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• Finally, you can try changing the camera settings in the software in order to see the best image as possible with the best resolution.

Fig. 7 Example of image taken with the optical microscope system. Gold electrodes with metallic contacts

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Low coverage images showing Pb adsorbed on a Si(111)7x7 superstructure. The UHV-STM images have been simultaneously taken using the retrace facility in WSxM. Image size 6nmx6nm. From LNM. Departmento Física de la Materia

Condensada UAM.

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Parque Cientifico de Madrid. Pabellon C, campus UAM. Cantoblanco E-28049 Madrid SPAIN Phone number: +34-914 973 436 Fax: +34-914 973 437 e-Mail: nanotec@nanotec.es

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