| AVS 64th International Symposium & Exhibition | |
| Applied Surface Science Division | Wednesday Sessions |
| Session AS+BI+MI+NS+SA+SS-WeM |
| Session: | Beyond Traditional Surface Analysis: Pushing the Limits |
| Presenter: | Arnaud Delcorte, Université Catholique de Louvain, Belgium |
| Authors: | C. Poleunis, Université Catholique de Louvain, Belgium V. Cristaudo, Université Catholique de Louvain, Belguim A.D. Delcorte, Université Catholique de Louvain, Belgium |
| Correspondent: | Click to Email |
Gas cluster ion beams (GCIB) have become the standard sources for molecular depth-profiling of organic materials with secondary ion mass spectrometry (SIMS) [1] and X-ray photoelectron spectroscopy (XPS). Since 2009, a number of experimental and theoretical studies were devoted to the investigation of the effects of energy, nuclearity and incidence angle of the Ar clusters on the energy deposition, fragmentation and molecular emission induced in organic solids [2-4]. Recently, Mochiji et al. reported that the backscattered Arn+ clusters observed in the SIMS spectra of pure metal surfaces provide information on the mechanical properties of the surfaces analysed by GCIB [5]. They correlated the ratio of Ar2+ to the sum of Arn+ clusters intensities with the impulsive stress caused by the impact, a parameter directly linked to the elastic modulus of the material.
Here, the intensity variations of the backscattered Arn+ clusters are studied as a function of temperature for a series of thermoplastic polymers: high molecular weight polydisperse polyisobutylene and polybutadiene, polystyrene (Standard; Mw = 4000) and polymethyl methacrylate (Standards; Mw = 2000 and 150000). For all these polymers, our results show a transition of the intensity ratio Ar2+/(Ar2++Ar3+) when the temperature is scanned from -120 °C to +125 °C. This transition generally spans over a few tens of degrees and the temperature of the inflexion point of each curve is very close to the glass transition temperature (Tg) reported for the considered polymer. Due to the surface sensitivity of the cluster backscattering process (a few nanometers as indicated by molecular dynamics simulations [4]), the presented analysis could provide a new method to specifically evaluate the surface Tg of polymers, with the same lateral resolution as the gas cluster beam. The results are discussed from the point of view of the structure and mechanics of polymers.
[1] S. Ninomiya, K. Ichiki, H. Yamada, Y. Nakata, T. Seki, T. Aoki, J. Matsuo, Rapid Commun. Mass Spectrom. 23, 2009, 1601.
[2] M. P. Seah, The Journal of Physical Chemistry C 117(24), 2013, 12622.
[3] B. Czerwinski, L. Rzeznik, R. Paruch, B. J. Garrison, Z. Postawa, Nucl. Instrum. Meth. Phys. Res. Sect. B 269, 2011, 1578.
[4] A. Delcorte, M. Debongnie, J. Phys. Chem. C 119, 2015, 25868.
[5] K. Mochiji, N. Se, N. Inui, K. Moritani, Rapid Commun. Mass Spectrom. 28, 2014, 2141.