Instruction manual

Introduction to the Digital Instruments MultiMode SPM

Microscope Speciﬁcations

Rev. B MultiMode SPM Installation Manual 13

1.3 Microscope Speciﬁcations

The MultiMode SPM can be ﬁtted with any of several scanners, depending upon the imaging

requirements. Generally, the smaller the scan, the smaller the scanner used. This is especially true

of atomic-scale scans, which are most often conducted with “A” or “E” scanners. Larger scans are

normally performed using “J” scanners.

1.3.1 Image Size and Resolution

Images consist of raster-scanned, electronic renderings of sample surfaces. There are three default

sizes: 128 x 128 pixels, 256 x 256 pixels, and 512 x 512 pixels. In addition, nine width-to-height

aspect ratios may be speciﬁed by the user: 1:1, 2:1, 4:1, 8:1, 16:1, 32:1, 64:1, 128:1 and 256:1.

Thus, it is possible to obtain “strip scans” which require less time to capture.

The controller provides 16-bit resolution on all three axes, 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 200µm laterally (in X and Y) and 10µm vertically (Z axis). Table

2.1a summarizes each scanner’s capabilities.

1.3.2 Scanning Techniques with the MultiMode SPM

The MultiMode is so called because it offers multiple SPM modes, including AFM, ECAFM,

ECSTM, STM and TappingMode. A complete range of Atomic Force Microscopy (AFM) and

Scanning Tunneling Microscopy (STM) techniques is available with the MultiMode SPM. Some of

these techniques are available only through Veeco.

• Contact AFM—Measures topography by sliding the probe’s tip across the sample

surface. Operates in both air and ﬂuids. See Chapter 6.

• TappingMode AFM— Measures topography by tapping the surface with an oscillating

tip. This eliminates shear forces which can damage soft samples and reduce image

resolution. TappingMode is available in air and ﬂuids (patented). This is now the

technique of choice for most AFM work. See Chapter 7.

• Phase Imaging—Provides image contrast caused by differences in surface adhesion

and viscoelasticity. Requires a Basic Extender Module in conjunction with a NanoScope

III or IIIA controller. See Chapter 7 and Chapter 13.

• 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 AFM or TappingMode.