Technical Specification of the Multimode SPM

This page gives a very basic specification and description of the instrument and contains links to the relevant sections of the manual. It is split into 3 sections:

Hardware
Scanning Techniques
Software
Consumables

Hardware

The NanoScope MultiMode AFM performs the full range of SPM techniques to measure surface characteristics including topography, elasticity, friction, adhesion, magnetic fields, and electrical fields. This microscope is ideal for smaller samples (maximum of 15 mm in diameter and 5 mm thick) for larger samples the Park Scientific Instruments Combined STM-SA1 and SFM-BD2 is availiable. The multimode allows both conductive and non-conductive samples to be studied. It supports contact, non-contact, Tapping Mode, lateral force, magnetic force, and electric force techniques, as well as STM and electrochemistry. It is equipped with an Extender Electronics Module that enhances magnetic and electric field imaging.

The innovative, compact and rigid construction of the hardware give the MultiMode SPM the mechanical stability and low noise needed for high resolution (it is capable of true atomic resolution). It is thus possible to easily acquire images on both the atomic and macroscopic scales. The hardware includes an optical detection head, TappingMode (air) Cantilever Holder, TappingMode Fluid Cell, Low-Current STM Converter, 2 scanners, and microscope base. An Optical Viewing System consisting of 450x optical viewing system with optical microscope, colour CCD camera, and colour monitor; provide vertical optical view of tip and sample. The Extender Electronics Module is also available: that contains phase and frequency detection hardware for Phase Imaging, MFM and EFM; required for Surface Potential measurements and recommended for all applications

The MultiMode SPM and Nanoscope IIIb control system are designed to provide superior scanning control combined with ease of use and reliability. The compact, rigid construction and low noise level make it the ideal microscope for atomic scale imaging. The short mechanical path length between tip and sample produces the high resonance frequency required for the fast scan rates that are essential for atomic resolution. In addition, careful choice of critical components ensures high thermal stability.

The controller provides 16-bit resolution on all three axes (x, y, and z scanner drives with ±220V range), with three independent 16-bit digital-to-analog converters (DACs) in x and y for control of the scan pattern, scaling, and offset. This configuration provides 16-bit resolution of the lateral scanning motion at any scan size, and the ability to perform atomic resolution imaging throughout the full lateral range of the scanner. The patented digital feedback is governed by integral and proportional gain controls, providing immediate response to scanning parameter changes.

The MultiMode can scan up to 100µm laterally (x and y axes) and 10µm vertically with the J scanner and up to 10µm laterally (x and y axes) and 3.5µm vertically (z axis) with the E scanner. The scanner calibration and linearization are maintained by software control, providing the user with easy, direct access to the calibration parameters of the scanner. The scanner maintains its calibration regardless of the scan size, offset, or direction. The patented design of the 12µm and 130µm lateral range scanners consists of a “hard” piezoelectric material for the vertical movement, which minimizes the effects of nonlinearity and hysteresis while maintaining calibration throughout the full vertical range.

Scanning Techniques

The complete range of Atomic Force Microscopy (AFM) and Scanning Tunneling Microscopy (STM) techniques is available with the MultiMode SPM:

Contact Mode AFM: Measures topography by sliding the probe tip across the sample surface; available for scanning in air and fluids.
TappingMode™ AFM: Measures topography by “tapping” the surface with an oscillating probe tip. This eliminates lateral shear forces on the tip and reduces the force normal to the tip and the surface which can damage soft samples; both of which can be detrimental to consistent image quality. Thus samples that are soft, fragile, particulate, or adhesive can be easily scanned in TappingMode, without risk of sample damage, while still maintaining the highest resolution. TappingMode imaging can be conducted both in ambient air and fluid environments. Note that Phase Imaging can also be performed simultaneously with TappingMode to provide additional information about the surface under examination.
Phase Imaging: Provides contrast caused by differences in surface adhesion and viscoelasticity; performed using TappingMode (patent pending).
Non-contact AFM: Measures topography by sensing Van der Waals attractive forces between the surface and the probe tip held above the surface; provides lower resolution than either Contact mode or TappingMode.
Magnetic Force Microscopy (MFM): Measures magnetic force gradient distribution above the sample surface; performed using LiftMode™ (see below) to track topography.
Electric Force Microscopy (EFM): Measures electric field gradient distribution above the sample surface; performed using LiftMode™ to track topography.
Surface Potential Microscopy: Measures differences in local surface potential across the sample surface; performed using LiftMode™ to track topography.
LiftMode™: A combined two-pass technique that separately measures topography (using TappingMode) and another selected property (magnetic force, electric force, etc.) using the topographical information to track the probe tip at a constant height above the surface (patented).
Lateral Force Microscopy (LFM): Measures frictional forces between the probe tip and the sample surface. If the scanner moves the sample perpendicular to the long axis of the cantilever, friction between the tip and sample causes the cantilever to twist. A photodetector position-sensitive in two dimensions can distinguish the resulting left-and-right motion of the reflected laser beam from the up-and-down motion caused by topographic variations. Therefore, it can measure tip-sample friction while imaging sample topography.
Scanning Tunneling Microscopy (STM): Measures topography of surface electronic states using the tunneling current which is dependent on the separation between the probe tip and a conductive sample surface. The Low-Current STM Converter allows operation in the sub-picoamp tunneling current region and hence can be useful when scanning poorly conductive samples.
Electrochemical Microscopy (ECAFM): Measures the surface structure and properties of conducting materials immersed in electrolyte solutions with or without potential control. A µAutolab type II potentiostat/galvanostat is available for more details contact the SAF.

Software

The microscope is controlled by powerful but easy to use control, image analysis and presentation software, that also contains powerful algorithms for the measurement and presentation of your results. You can view your images in two- and three-dimensional representations, with a variety of color schemes with the ability to design your own. You can also analyze your images with a variety of algorithms, including:

Several image modification algorithms are also provided, including:

With the “Auto Program” feature, an off-line macro routine can be easily created to perform a series of analysis and modification steps with or without the user present. The results are stored in files which can then be printed or exported as ASCII files for use with other software packages. Similarly, NanoScope image files can also be exported and imported as TIFF or ASCII files for use with other software.

Consumable Costs

Contact Mode Probe	£7.50
Tapping Mode Probe	£50

For more details on these probes click here.

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