Development of Unique Specimen Holder for LEED-AES Study at High Temperatures

Low‐energy electron diffraction study of atomic structure of Sc–O/W(100) surface acting as Schottky emitter at high temperatures

“…The apparatus and specimen holder are described in detail elsewhere. 14 The as-received mechanically polished W(100) disk (Rare Metallic, Japan) was etched electrochemically using an NaOH solution (2.4 mol l 1 ) to remove the heavy carbon contamination on the surface, which is believed to be caused by the diamond powder used in the mechanical polishing process. After electrochemical etching, the W(100) specimen surface was cleaned in the experimental apparatus under ultrahigh vacuum (UHV) by repeating the sputtering and flashing at ¾1900 K until no contaminant-induced AES peaks were observed, except for the small oxygen-induced AES peak (see Results section).…”

“…7 The pressure in the apparatus was maintained at <1 ð 10 9 Torr when heating to 1500 K and at <5 ð 10 9 Torr when heating to 1900 K. A digital still camera (DSC-D700, Sony) was used to record the LEED pattern. Digital image processing of the LEED patterns observed at the high temperatures was performed to improve the contrast of the pattern by filtering the red and blue components of the image, 14 which are caused by the black-body radiation emitted by the specimen. Figure 2 shows a series of LEED patterns, as observed at each stage of the Sc-O/W(100) surface preparation: the clean W(100) surface; after deposition of ¾1 monolayer of scandium; after oxygen exposure; and after heating to 1500 K for 3 min.…”

Self-recovery function of Sc–O/W() system as Schottky emitter

“…The specimen holder was specially developed to enable AES measurement and LEED observation at the operating temperature of the Sc-O/W(1 0 0) emitter. The details of the specimen holder and the experimental arrangement are described elsewhere [13].…”

Self‐recovery function of p(1×1)‐Sc‐O/W(100) system used as Schottky emitter

“…The sample holder was one previously developed to perform the AES measurement and LEED observation at the operating temperature of the Sc-O/W(100) Schottky emitter. 14 The sample was a W(100) disk (5 N, diameter 9 mm ð 0.5 mm). The sample temperature was controlled by the electric power used for heating, which was calibrated in advance using a pyrometer (IR-AP, CHINO).…”

“…14 The AES measurement was performed using 5 keV electrons of 0.1 µA. The incident energy and beam current of electrons for the LEED observation were ¾60 eV and ¾1 µA, respectively.…”