Determination of the Inelastic Mean Free Path of Electrons in Different Polyaniline Samples

Abstract

Polyaniline specimens, emeraldine sulfate, emeraldine hydrochloride, and emeraldine base, were characterized by infrared spectroscopy, X-ray photoelectron spectroscopy, elastic peak electron spectroscopy, and density measurements using helium pycnometry. This work has been stimulated by a considerable interest in potential technological applications of polyaniline. The chemical state of polyaniline has been verified with infrared spectroscopy. X-ray spectroscopy was used for the qualitative and quantitative surface composition analysis of studied samples. The inelastic mean free path of electrons has been determined from the measurements of the elastic electron backscattering probability. This is one of the most frequent applications of elastic peak electron spectroscopy. The inelastic mean free path is needed for the quantitative analysis of polyaniline surface using electron spectroscopies. The method of elastic peak electron spectroscopy utilizes the theoretical model of the electron transport, accounting for the multiple elastic scattering events in the studied material. The inelastic mean free path values have been measured in the energy range 400−1600 eV. The resulting dependence has been compared to the values obtained using the G1 predictive formula of Gries.

Influence of Recoil Effect and Surface Excitations on the Inelastic Mean Free Paths of Electrons in Polymers

“…The helium pycnometry densities for polythiophenes reported elsewhere [10] are similar (around 1 g cm −3 [10]). For undoped and metal doped polymers the density values vary between 0.9 g cm −3 and 1.6 g cm −3 [6][7][8][9][10]. Comparison of polythiophenes nominal and XPS composition indicates contamination of Cl, Si, Na, and O, resulting from the synthesis environment.…”

“…The helium pycnometry method for bulk density determination in porous materials, described in detail by Presz et al [33], was previously applied for determining the bulk density of conductive polymers [6][7][8][9] and investigated polythiophenes (Ref. [10], Table 1).…”

“…For determining the IMFPs in polymers, the predictive formulae such as the TPP-2M formula of Tanuma et al [3], the G1 formula of Gries [4] and the quantitative structure-property relationship proposed by Cumpson [5] can be used. The IMFPs obtained from the EPES method have been published for selected conductive polymers, such as polyacetylenes, Pd doped polyacetylenes [6,7], polyanilines [8,9], and polythiophenes [10]. Discrepancies between measured [6][7][8][9][10] and predicted IMFPs [3,4] have been observed.…”

“…The IMFPs obtained from the EPES method have been published for selected conductive polymers, such as polyacetylenes, Pd doped polyacetylenes [6,7], polyanilines [8,9], and polythiophenes [10]. Discrepancies between measured [6][7][8][9][10] and predicted IMFPs [3,4] have been observed. Part of the deviations can be ascribed to some problems in determination of IMFPs in polymers by the EPES method.…”

Determination of the inelastic mean free path of electrons in polyaniline samples by elastic peak electron spectroscopy

“…21,22 They have also been published for polyanilines protonated using various acids, such as polyaniline sulphate C 24 N 4 H 20 SO 4 , polyaniline hydrochloride C 24 N 4 H 20 Cl 2 and deprotonated polyaniline base C 24 N 4 H 18 . 23 The synthesis procedure of organic samples and its precise reproductibility are of crucial importance. Because it is not possible to avoid synthesis of the samples without contamination due to the reaction or atmosphere environment, precisely measured surface composition evaluated by photoelectron spectroscopy should be considered when determining IMFPs by the EPES method.…”