X-ray photoelectron spectroscopy (XPS, aka ESCA) permits elemental and chemical spectroscopic analysis of both conductive and insulating samples, with high depth resolution (10 nm or less), good elemental sensitivity (0.1 to 0.01 atomic percent), and lateral resolution down to 10 um. Changes in elemental composition with depth (to a maximum depth of about 10 nm) can be documented nondestructively by recording surface composition while varying sample tilt relative to the analyzer (this technique is called angle-resolved depth profiling). Compositional changes with depth down to a few hundred nm can be observed by recording surface composition while using an ion gun to gradually remove surface layers. The spatial distribution of elements or chemistries on a surface can be mapped with a lateral resolution of down to ten microns. The sample is analyzed in an ultra high vacuum chamber. CMSE's PHI Versaprobe II XPS has a C60 cluster-ion gun as well as a floating voltage argon single-ion gun for depth profiling. The cluster-ion gun permits depth profiling softer materials which would be too damaged by single-ion bombardment. Other features of this XPS are a portable transfer vessel so that processed samples can be loaded into the XPS without exposure to air; an in situ heat/cold stage (-120C to 500C); and X-ray induced secondary electron imaging (SXI), which aids significantly in setting up for small area analysis.