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Thermal Desorption Mass Spectrometry
Published in Arthur T. Hubbard, The Handbook of Surface Imaging and Visualization, 2022
C. Nicole Chittenden, Eddie D. Pylant, Amy L. Schwaner, J. M. White
TPD may also be used in conjunction with static secondary ion mass spectrometry (SSIMS). This technique uses low energy, low current (≈0.5 kV, ≈1 nA) argon ion beams to eject ionized and neutral species from the surface.15 The ionized fragments are detected by a mass analyzer (the electron beam ionizer is turned off). Provided the ionized fragments and their intensities can be related to one or more surface species, we can extract kinetic parameters that describe the accumulation or loss of surface species. This method is particularly effective in its temperature-programmed version, TPSSIMS, because it gives both qualitative and quantitative information about the molecular species remaining on the surface at a given temperature. Operationally, SSIMS uses a very low flux of argon ions rastered (moved back and forth across the sample to facilitate even sputtering) over the surface to minimize sputtering damage. A sufficiently low current reduces the likelihood that any given surface site will be struck more than once during an experiment.
Influence of Surface Structure on Polymer Surface Behavior
Published in Kunio Esumi, Polymer Interfaces and Emulsions, 2020
Segmented poly(ether urethane)s (PEUs) and model polymers were examined by using static secondary ion mass spectrometry (SIMS) and XPS [32]. The PEUs were composed of a polyether [either poly(propylene glycol) (PPG) or poly(tetramethylene glycol) (PTMG)] capped with methylenebis (phenylene isocyanate) (MDI) and chain-extended with ethylenediamine. Model soft segments included poly(ethylene glycol), PTMG, and PPG of various molecular weights. Hard-segment models for the PTMG PEUs were based on MDI and butanediol, whereas those for the PPG PEUs were based on MDI and dipropylene glycol or tripropylene glycol. This study confirmed the enrichment in polyether at the PEU surface; however, it suggested that this surface layer of polyether is not pure but is interspersed in the uppermost 10-15 5 with small quantities of hard-segment components.
Surface Degradation of Oxides, Ceramics, Glasses and Polymers
Published in Ken N. Strafford, Roger St. C. Smart, Ian Sare, Chinnia Subramanian, Surface Engineering, 2018
While FT-IR has been valuable in relating the chemistry of the near-surface to structural changes in the material during environmental degradation, for many studies such as adhesion and biocompatibility of polymers, actual surface information in the first 1–10 nm is required. The analysis of functional groups resulting from oxidation reactions in this top layer is the goal of much polymer surface analysis. The modern surface analysis techniques already described for the study of metals, ceramics, and glasses are readily adaptable to the study of the surface structure of polymers. XPS has been the most widely emplyed [63], but it has been shown that some modification of the technique, notably surface derivatization [51,52,60,64], may be required in order to analyse the wide range of groups described previously. However, there are particular requirements that must be met because of the inherent instability of some polymers to radiation and ion sources, as well as the surface restructuring that occurs in a viscoelastic material [60]. These particular requirements for successful polymer surface analysis will be discussed in the context of examples that show the power of X-ray photoelectron spectroscopy and static secondary ion mass spectrometry in solving specific surface engineering problems.
Understanding the fundamentals of TiO2 surfaces
Published in Surface Engineering, 2022
The co-adsorption of CO2 with H2O on defect-free and reduced rutile (110) surfaces was investigated with TPD, static secondary ion mass spectrometry (SSIMS), and HREELS by Henderson [253]. It was found that water inhibited CO2 adsorption on nearly perfect surfaces. On the non-stoichiometric vacuum annealed surfaces, only simultaneously dosed H2O and CO2 molecules interact leading to the formation of bi-carbonate species [253].