Peltier cooling stage

Figure 3.17. Scheme of the wet-STEM imaging mode, a Peltier cooling stage b TEM-grid type sample holder c annular detector for transmitted electrons collection i incident electron beam. 

For frozen samples Peltier cooling stage (e.g., Ferrotec Corp., Bedford, NH, USA) with heat fan (e.g.. Allied Electronics, Inc., Eort Worth, TX, USA), and DC power supply. 

The Unisantis XMF-104 X-ray microanalyzer (Unisantis S.A., www.unisantis.com) was used by researchers at the Institute for Roentgen Optics, Moscow, Russian Federation, to examine nonde-structively the composition of ancient coins from the fourth century BC through the second century AD. The fourth century BC coins were found to be an alloy of 82% Ag/18% Cu, but areas of pure Ag showed the inhomogeneity of the alloy. A drachma coin depicting Alexander was composed of 99% Ag/1% Cu. The XMF-104 system had a 50 W Mo tube, a 2-stage Peltier-cooled compact Si-PIN detector and polycapillary focused X-ray beam with a 50-250 pm focal spot. Spectra, images of the coins, and details are available at www.unisantis.com, application note 605. 

In modern DHS instrumentation the two-stage thermal desorption process consists of tube desorption onto a Peltier-cooled trap, followed by trap desorption of the heated trap. Peltier-cooled focusing traps concentrate volatile organics without liquid cryogen. Rapid thermal desorption of the focusing trap (40°C/s) produces component bands about 1 s wide for uncompromised narrow-bore CGC. Flexible split-ratio selection facilitates a wide range of applications from trace level to percent levels of... 

Von Seggern, C. E. Gardner, B. D. Cotter, R. J. Infrared atmospheric pressure MALDI ion trap mass spectrometry of frozen samples using a Peltier-cooled sample stage. Anal. Chem. 2004, 76, 5887-5893. 

The Peltier heating/cooling stage allows working within 20 °C above or below ambient temperature, and the combination of low temperature (e.g., 4 °C) and high water vapor pressure (e.g., 6.1 Torr) permits achievement of 100% relative humidity (RH) at the sample surface. At 100% RH, samples are not dehydrated during the imaging process. At less than 100% RH, a moist sample constantly loses water as the vacuum in the chamber pumps on it in the scope, it appears as constant movement of the sample. 

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