Scanning Electron Microscope and X-ray analysis:

Scanning electron microscopy (SEM) is one of the most versatile and well known analytical techniques. Compared to conventional optical microscope, an electron microscope offers advantages including high magnification, large depth of focus, great resolution and ease of sample preparation and observation. Electrons generated from an electron gun enter a surface of a sample and generate many low energy secondary electrons. The intensity of these secondary electrons is governed by the surface topography of the sample. An image of the sample surface is therefore constructed by measuring secondary electron intensity as a function of the position of the scanning primary electron beam.

In addition to secondary electrons imaging, backscattered electrons imaging and Energy Dispersive X-ray (EDX) Analysis are also useful tools widely used for chemical analysis. The intensity of backscattered electrons generated by electron bombardment can be correlated to the atomic number of the element within the sampling volume. Hence, qualitative elemental information can be revealed. The characteristic X-rays emitted from the sample serve as fingerprints and give elemental information of the samples including semi-quantitative analysis, quantitative analysis, line profiling and spatial distribution of elements. SEM with X-ray analysis is efficient, inexpensive, and non-destructive to surface analysis. It has wide ranges of applications both in industry and research.

In the CSAR, a state-of-the-art high resolution LEO 1530 field emission scanning electron microscope with EDX system from OXFORD is available. It is a high performance instrument designed for analytical applications featuring the GEMINI column technology. It is controlled by a 32 bit computer system using Microsoft Windows NT as operating system.

Figure 1 Schematic diagram of the LEO 1530 Field Emission SEM.

Figure 2 LEO 1530 Field Emission SEM.

　

LEO 1530 Specifications:

Resolution: 1.0nm at 20KV WD=2mm

2.1nm at 1KV WD=1mm

Accelerating Voltage: 0.1KV to 30KV continuously variable in 10 volt steps.

Magnification: 20X to 900KX

Probe current: 4pA to 10nA

Electron gun: thermal field emission type

Detectors: In-lens annular, Secondary Electron (SED), Backscattered Electron (BSD)

EDX: working distance 8.5mm

Image Processing: pixel averaging, frame integration, continuous averaging

Image Resolution: 512 x 384 to 3072 x 2304 pixel

Some SEM Image measured by LEO1530 Scanning Electron Microscope:

Low reolution SEM image of CNT

High reolution SEM image of CNT

SEM image of pattern photoresist deposited on silver substrate fabricated by e-beam lithography.

High reolution SEM image of gold film deposited on carbon substrate.

Some SEM/EDX result measured by LEO1530 Scanning Electron Microscopy:

SEM image of Indium Gallium Nitride film.

EDX spectrum of Indium Gallium Nitride film.

SEM and EDX Mapping Measured by LEO1530 Scanning Electron Microscopy:

SEM Image	EDX Mapping of Carbon	EDX Mapping of Copper
EDX Mapping of Zinc	EDX Mapping of Platinum

**** Application of SEM on Ecology ****