BSE Imaging of Wet Samples at Room Temperature (1981-1985)
Highly efficient backscattered electron (BSE) detectors , as shown below, have allowed ESEM examination of truly wet specimens at room temperature using low beam accelerating voltage and current. No beam damage is detected during examination. Surface properties can be studied by observing the reaction with various liquid media. (5), (6), (17), (18).
It must be noted that the images shown below were obtained at room temperature under saturation water vapor pressure around 2000 Pa with 10 kV electron beam. This was done routinely without the need to use a cooling device to lower the wetting water vapor pressure. Furthermore, this particular ESEM design allowed the maximum possible distance of the specimen from the pressure liming aperture, which, in turn, allowed the insertion of a capillary needle to inject water droplets from ambient pressure in a controlled manner (27). Unfortunately, the latest commercial instruments have retrogressed to very crude operational conditions at low pressure and high kV, which at the same time require the use of a cooling stage. The problem is demonstrated in part by the incorrect geometry of the gaseous flow (56). Unnecessary constraints on the working distance, pressure, temperature and beam kV often result in a cumbersome situation. In a properly designed commercial ESEM, condensation of water droplets on a specimen surface should be practiced when an application calls for it, whilst a microinjector allows other favorable experiments to be uniquely conducted. ____MORE
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Measurement of receding contact angle of fiber-water surface system(18) | |
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Fibers partially immersed in water (6) |
Live Leptospermum flavescens seedling cells in equilibrium with water(5) |
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Calculated shapes of scintillating BSE detectors yielding optimum electron detection and light conduction(17) |
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Assembly of two symmetrical scintillating BSE detectors
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Closer view of previous assembly
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Close-up view from below of assembly of BSE
detectors
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Relative size of one of the detectors mounted on
the.
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Bottom view without aluminium foil. |
Side view (upside-down) |
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