Sesame seeds, by near-ambient pressure XPS

Abstract

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., greater than ca. 2500 Pa. With NAP-XPS, XPS can probe moderately volatile liquids, biological samples, porous materials, and/or polymeric materials that outgas significantly. In this submission, we show NAP-XPS of sesame seeds, a food sample that could not be analyzed at moderate pressures by conventional approaches. Survey spectra from three separate seeds are shown. In addition to the expected C 1s and O 1s signals, seeds show calcium. The C 1s narrow scans from the three seeds are well fit by four components. The largest of these is attributed to carbon singly bonded to oxygen (C—O), which suggests carboydrates or cellulose in the material. A small N 1s peak is observed in all the survey spectra.