Ultrahigh vacuum sample mount for x-ray photoelectron spectroscopy up to very high temperature (150–1400 K)
(Color online) UHV heater cartridge, showing three main parts: (a) W–Re leads with Mo overwrap are electrically isolated from the shell, (b) molybdenum body shell, a cylinder of diameter of 0.200 in. and length of 0.300 in., and (c) filler surrounding the heater element. A bare heater is rated to reach 1375 K with 8.5 W input. The heater cartridge was manufactured by HeatWave Laboratories, Inc. part 101120 with a maximum input power of 17 W.
(Color online) UHV sample mount with cartridge heater: perspective front and back views. (H) Top view of cartridge heater shown in Fig. 1, (HS) stainless steel heat shield, (B) stainless steel bracket, and (S) Cu heat sinks. Not shown here are a stainless steel heater clamp, ceramic standoffs used to electrically isolate the heater cartridge support, and a -type thermocouple in contact with the heater cartridge secured with Ta wire. The highest temperature reached was 1300 K, with an input power of 15 W.
(Color online) UHV sample mount with cartridge heater: full front and side cross-section views. (h) Cartridge heater, (HS) stainless steel heat shield, (b) stainless steel bracket, (s) Cu heat sinks, and (c) stainless steel heater clamp. All fasteners are standard stainless steel components.
(Color online) Dynamic temperature response of the cartridge heater as configured in Fig. 2, shown by plotting the reduced temperature of the sample stage as a function of time. Reduced temperature is defined here as . Here, is the temperature at variable time , is the temperature for a given setting of the Variac, and is the estimated final plateau temperature. The sample stage was mounted in an offline UHV chamber with a -type thermocouple secured to the heater cartridge body with a wrap of Ta wire. The data symbols defined in the legend refer to applied heater voltages as specified in Table I.
(Color online) High-temperature XPS shown together XRD data for . The Mn features (left panel) show a clear temperature dependence between room temperature and 1315 K. This is consistent with the XRD data in the right panel (325–1330 K), shown for a sample from the same batch.
(Color online) Photograph of the actual UHV heater stage described in this article, mounted on a manipulator arm for use in a cylindrical mirror analyzer chamber. Labels show parts A–D, as follows. (a) Stainless steel set screw. (b) Single crystal sample of held in a Ta basket in front of cartridge heater, (c) dewar, (d) picoammeter lead connected to sample mount, and (e) stainless steel heat shield surrounding the heater cartridge.
(Color online) XPS measurements on as temperature is cycled, demonstrating that the changes in core level structure at high temperature is reversible with temperature cycling. Panel (a) shows the first measurement at room temperature. Data in panel (b) were collected after sample temperature was initially raised to 1315 K. Subsequently, the sample was cooled back to room temperature and data were collected as shown in panel (c). Panel (d) then shows data collected after the sample was heated once again to 1350 K. This repeatability was confirmed more than once.
High-temperature XAS measurements of in total-electron yield mode. Note two main features, which we assign to Fe and Fe . Note also a shoulder at 703 eV near the Fe feature. All three features show a definite temperature dependence between room temperature and 770 K, indicating a possible change of valence state. The signal fails at the highest temperature, perhaps due to electron flooding.
Resistive heater calibration data measured using different probes.
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