問い合わせ番号

INS-0000000396

Ultra-high vacuum (UHV) surface X-ray diffractometer located at the experimental hutch 3

  A pack of three ultra-high vacuum chambers are available; one of the chambers will be mounted on a S2+D2 diffractometer (UHV diffractometer) (See fig.3). Capabilities of the instrument include X-ray scattering studies in grazing incidence, studies of crystal truncation rods, reflectivity measurements, and X-ray standing waves in ultrahigh vacuum. Examples of measurements that will be expected are the following: observation of a dynamic change in an atomic structure at a crystal surface (e.g. phase transition), analysis of a super structure formed on the surface. The chambers are equipped with a low energy electron diffraction optics, a reflection high energy electron diffraction gun and its fluorescent plate, an evaporation source, a gas doser, a sputtering gun, a quartz thickness monitor, a quadrupole mass spectrometer, and a background ionization gauge. The UHV diffractometer has two degrees of freedom (DOF) on the sample and two independent DOF on the detector. The diffractometer is about 3.2 m × 3.2 m × 2.3 m in dimension. The sample is rotated around a horizontal axis ω, which rotates about a vertical axis α. (Note, the ω axis is attached to a UHV chamber. The chamber also rotates with α.) The detector is rotated around a horizontal axis δ, which rotates about a vertical axis γ. Angular resolutions per motor step are listed in Table 2.

Fig. 3. The UHV diffractometer (upper) and a UHV chamber mounted on the UHV diffractometer (lower) in experimental hutch 3.

• Table 2. Angular resolutions per motor step for the axes of the UHV diffractometer in a full step mode of motor drivers

  Axis	Step (arc sec)
  ω1	0.72
  ω2	0.72
  ω3	0.09
  α	0.36
  δ	0.36
  γ	0.36
  μ	3.6