Development of Ti Kα x radiation for electron spectroscopy for chemical analysis of polymer surfaces

Abstract

It has been shown previously that implementing x-ray sources of different energies for electron spectroscopy for chemical analysis (ESCA) of various materials can be useful. In this study ESCA with Ti Kα x radiation as the excitation source is explored for the analysis of some common technical polymers. The investigation of these polymers is used to illustrate the usefulness of a Ti Kα x-ray source with respect to increasing the depth of ESCA analysis as well as its use in the analysis of atoms with high-binding-energy core level (1s) electrons, which are normally inaccessible to ESCA experiments using Mg Kα or Al Kα x radiation. Through the use of polymer standards a list of calculated sensitivity factors for C, N, O, F, Si, P, S, and Cl is derived from ESCA experiments utilizing Mg and Ti Kα x radiation. Also presented are corrected photoelectron binding energies, x-ray excited Auger kinetic energies, and modified Auger parameters (α′) which are accessible by Ti Kα radiation. Discussion of Ti Kα x-ray satellites is included with subsequent curve resolution results of core level photoemission from elements as well as polymer materials containing elements in different chemical states. Finally, the use of the new sensitivity factors is illustrated along with the increased depth profiling ability through the investigation of a segmented poly(ether–urethane) block copolymer system in which nitrogen containing ‘‘hard’’ segment domains are thought to segregate away from the surface into the bulk.