ABSTRACT
The title of this section includes the two most commonly used names for the field. Although the term photoelectron spectroscopy may correctly be used to denote the whole field, it frequently is used more narrowly to specify the use of ultraviolet radiation as the ionizing source, while ESCA refers to the use of X-radiation. The use of this distinction has been continued in preparing this section for the following considerations: ESCA has a much greater energy range than photoelectron spectroscopy with a corresponding loss of resolution. Furthermore, while calibration in photoelectron spectroscopy is a routine procedure, a wide variety of methods and standards are used in ESCA so that reported ionizations are useful only when the calibration method used is known. Thus, Tables 1 and 2 on ESCA have only vertical ionizations that include the calibration method. Valence band ESCA has been put into a separate table since it covers the energy region of photoelectron spectroscopy, but is limited by the lower resolution of ESCA.
