ALISS and ARXPS Chamber
The atomic or geometric structure of surfaces and adsorbed layers is probed in this chamber by angle-resolved alkali ion-scattering spectroscopy (ALISS) and angle-resolved XPS (to detect forward-scattering or x-ray photoelectron diffraction (XPD)). This instrument is a two-level UHV chamber with a rotatable ion analyzer for forward scattering (sensitive to adsorbed H) and nearly direct backscattering (ICISS) of rare gas and alkali ions from a differentially pumped Colutron 10 kV ion gun. An additional Perkin-Elmer Model 10-360 Hemispherical Analyzer (SCA) with multichannel detection (MCD) for a 16-fold enhancement in the signal is used for ICISS and XPS or XPD. The sample manipulator is constructed with computer/stepping motor control of polar and azimuthal angles, providing essentially a goniometer onto which the sample can be mounted. The chamber also includes capabilities for AES, UPS, XPS, LEED, and TPD.