Mass spectrometric study of low energy Cs+ ion-induced sputtered fragmentation of PADC polymer

Abstract

In this study, low-energy cesium (Cs⁺) ion-induced sputtered fragmentation of poly allyl diglycol carbonate (PADC) was investigated using mass spectrometry. The collision-induced dissociation mechanism revealed emission of various fragments, including monoatomic (H⁻, C₁⁻, O₁⁻), diatomic (C₂⁻), and multiatomic (C₃⁻, CO₂⁻, C₂O₂⁻, C₃O₂⁻) species within the Cs⁺ ion energy range of 1–5 keV. The anion current of these fragments exhibited a linear increase with rising incident Cs⁺ ion energy, indicating a corresponding rise in fragment abundance. Analysis of normalized yield indicated that at 1 keV incident energy, the dominant fragment was monoatomic hydrogen (H⁻), followed by diatomic carbon (C₂⁻), monoatomic carbon (C₁⁻), and monoatomic oxygen (O₁⁻). Although C₂⁻ remained dominant up to 5 keV, other fragments exhibited varying normalized yields at different ion energy steps. The sputter yield estimation revealed that monoatomic hydrogen (H⁻) and diatomic carbon (C₂⁻) exhibited the highest yields, increasing exponentially beyond 3 keV, while multiatomic fragments like C₃⁻, CO₂⁻, C₂O₂⁻, and C₃O₂⁻ displayed the lowest yields. The sputter dissociation mechanism pointed to dehydrogenation, chain scission, and bond breakage as the primary processes during low-energy Cs⁺ ion impact. Postsputtering Scanning Electron Mircoscope (SEM) micrographs show craters, pits, and micropores on the PADC surface, indicating significant surface degradation. X-ray Diffraction (XRD) spectra exhibited reduced diffraction intensity, while Fourier Transform Infrared Spectroscopy (FTIR) analysis indicated the absence of molecular bands in the IR spectrum, confirming extensive surface damage due to Cs⁺ ion-induced sputtering.