Polytetrafluoroethylene, by near-ambient pressure XPS

Near-ambient pressure–x-ray photoelectron spectroscopy (NAP-XPS) is a less traditional form of XPS that allows samples to be analyzed at relatively high pressures, i.e., at greater than 2500 Pa. With NAP-XPS, XPS can probe moderately volatile liquids, biological samples, porous materials, and/or polymeric materials that outgas significantly. Polytetrafluoroethylene (PTFE) is an important polymer with many applications in science and industry. It is an insulator that charges under x-ray illumination at high vacuum. In this submission, we show NAP-XPS spectra of PTFE. Survey spectra are shown at different background gas (air) pressures. These spectra contain F 2s, C 1s, O 1s, N 1s, F 1s, and F Auger signals. Also presented are F 1s narrow scans over a range of background pressures and illumination times. Peaks decrease in width, shift toward literature values, and improve in shape with increasing background gas pressure.