Acquisition of a Zeiss FE-SEM Sigma 360VP

The Natural History Museums of Denmark house 14 million unique specimens in both dry, wet and living collections. The collections in the museum are of high value and interest to researchers around the world, and the specimens have been meticulously collected and studied over the past 400 years. Based on specimens from the collections, we undertake research in biodiversity and geology with the potential of improving our general understanding of the natural world.

Only Zeiss FE-SEM Sigma 360VP has the performance that are critical for the quality of our research. While we have a large and diverse group of users, a significant number of researchers for their work on microorganisms (e.g., microalgae) depend on high resolution at high magnifications. The Zeiss FE-SEM Sigma 360VP FE-SEM has the best performance for this purpose.

The Zeiss FE-SEM Sigma 360VP has the best performance for our purpose due to the combination of Shottky Gun and a beam boaster designed to maintain highest resolution in high or low beam energy, without using sample deceleration (sample bias).

In comparison the objective lens design of this FE-SEM provides a reduced magnetic field at the specimen surface which means high-resolution imaging of dia-, para-, or ferromagnetic samples - in any composition and together with other materials - is possible even at short working distances and low beam energy. High resolution imaging of ferromagnetic steel @ WD = 3 mm; AV = 1 kV @ 100.000x Mag must be possible.

Ease of use. There has to be an electromagnetic 7-hole aperture changer incorporated close to the emitter system. In combination with a magnetic field lens the optimum beam aperture angle is selected and hence tunes the probe current. The system is always in resolution mode with the standard aperture (e.g. 30 μm). No spot aperture adaptation is necessary at any beam energy.

An annular and high efficiency In-lens detector has to be integrated in the beam booster located above the objective lens. The detection material does not show any aging effect. This detector has to provide best SE-resolution. The acquisition time for a noise-free image has to be less than 1 second.

An Everhart-Thornley SE-detector mounted at the specimen chamber has to be provided. The detector must be designed with a shielding to minimize charging effects when imaging non-conductive samples in high vacuum.

The SEM will have a high precision fully motorised Cartesian stage allowing movements of X = 125 mm, Y = 125 mm, Z = 50 mm, T = -10º to 90º, and R = 360º.

The stage will accommodate samples of up to 0.5 kg with the full range of motion, up to 2 kg without tilt and up to 5 kg with the sample mounted directly to the XY platform.

GUI control via Touch Screen or/and mouse/keyboard control makes it very easy and convenient to use.

EDX system with quantitative analysis based on deconvoluted overlaps of element peaks. The major advantages over conventional techniques are that the shape of the background need not be known explicitly, there Is no need to find suitable points away from peaks for background scaling, and any background that is approximately linear over the range covered by a single peak will be effectively removed.