Imaging Modes

Different imaging methods or different uses of the microscope may be used to highlight different features of the surface. Appropriately tuning the electron kinetic energy allows for step contrast in bright field microscopy to be achieved. Similarly, the contrast originating from different electron reflectivities (that can be due to different crystalline structures, different number of heteroepitaxial layers or different surface composition), will induce a contrast that is referred to as reflectivity contrast in bright field microscopy.

Structural contrast in dark field microscopy can also be achieved by imaging with diffracted beams. The resulting image is “dark” where the crystal has not given rise to the diffracted beam and different gray tones for the regions producing the imaged diffracted beam.

Furthermore, the diffraction or LEED pattern originating from a small region of the surface (down to 100 nm) can be directly imaged by changing lens voltages clicking on the appropriate preset option. The direct imaging of a diffraction pattern is advantageous for LEED-IV analysis because the diffracted spots do not move on the image upon changes of the electron kinetic energy. The LEED can be simultaneously overlapped with the PED pattern.

If available, the spin-polarized electron gun can be used to image magnetic domain imaging with in- and out-of-plane magnetization at high acquisition rate.

Please feel free to click on the pictures in the sidepanel to enlarge them.

Bright field – reflectivity contrast

LEEM-BF-Reflectivity-Cu_W110_6_4eV-and-8_4eV_med
Reflectivity contrast of Cu on W(1 1 0) with at 6.4 and 8.4 eV, respectively. (Courtesy of M. Altman)