Advances in charge neutralization for XPS measurements of nonconducting materials

The build‐up of a positive charge during the XPS measurement of nonconducting materials can severely affect the spectral resolution leading to line broadening and time‐dependent energy shifts. The use of a low kinetic energy electron flood gun in conjunction with a metal screen placed in close proximity to the sample surface permits the establishment of a uniform surface potential. The advantages of this approach are demonstrated with spectral data taken from a variety of organic materials. Spectral line widths of 0.9–1.3 eV are routinely obtainable for the C(1s) core level photoelctron signals. Further, the reproducibility obtained on line positions (±0.1 eV) allows the use of a calibration procedure to study the relative line positions between different samples. This combined with better resolution allows a more complete assignment of spectral features including some nearest neighbor effects. A shift between aromatic and aliphatic C(1s) lines is observed.