Clamshell, 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. In this submission, we show NAP-XPS survey, Ca (3p, 2p, 2s), O 1s, C 1s, and N 1s narrow, and valence band spectra from a clamshell, a material of biological origin that would be challenging to analyze by conventional XPS approaches. Like most shells of biological origin, clamshells are primarily composed of calcium carbonate.