Photoelectron Emission Microscopy and its Application to the Study of Polymer Surfaces

Cossy-Favre, A.; Dı́az, J.; Anders, S.; Padmore, H. A.; Liu, Y.; Samant, Mahesh G.; Stöhr, J.; Brown, Hugh R.; Russell, T. P.

doi:10.12693/aphyspola.91.923

Cited by 10 publications

(4 citation statements)

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“…Furthermore, if the polymers are in the liquid state then the Newman, rather than the Young's contact angle, must be determined 9 which requires a precise knowledge of the curvature of the polymer/polymer interface. We present here the combination of near-edge x-ray absorption fine structure ͑NEXAFS͒ imaging in transmission 11,12 and surface sensitive modes 13,14 as a new approach to characterize polymer thin films and investigated model thin films of blends and bilayers of polystyrene ͑PS͒ and brominated polystyrene ͑PBrS͒.…”

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confidence: 99%

Bulk and surface characterization of a dewetting thin film polymer bilayer

Ade

Winesett

Smith

et al. 1998

Applied Physics Letters

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We have monitored the progression of the dewetting of a partially brominated polystyrene ͑PBrS͒ thin film on top of a polystyrene ͑PS͒ thin film with scanning transmission x-ray microscopy ͑STXM͒ as well as photoemission electron microscopy ͑PEEM͒. We mapped the projected thickness of each constituent polymer species and the total thickness of the film with STXM, while we determined the surface composition with PEEM. Our data show that the PBrS top layer becomes encapsulated during the later stages of dewetting and that atomic force microscopy topographs cannot be utilized to determine the contact angle between PBrS and PS.

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Bulk and surface characterization of a dewetting thin film polymer bilayer

Ade

Winesett

Smith

et al. 1998

Applied Physics Letters

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“…Since such states are specific to the bonding within different functional groups, NEX-AFS can be used to probe the chemical composition of polymers. 15,16 The intensity of the NEXAFS resonances depends on the nature and filling of the molecular orbitals and on the included angle between the electric field vector of the X-rays E B and the direction of the valence orbital. 17 The use of nearly linearly polarized light produced by a synchrotron enables one to access the orientation of chain segments near the surface.…”

Section: Introductionmentioning

confidence: 99%

“…Near-edge X-ray absorption fine structure (NEXAFS) has been shown to be a unique tool to probe the surface structure and bulk orientation of polymer films. , Near the K-shell absorption threshold, NEXAFS spectra are dominated by resonances arising from transitions from the 1s core level to unfilled molecular orbitals of π* and σ* symmetry. Since such states are specific to the bonding within different functional groups, NEXAFS can be used to probe the chemical composition of polymers. , The intensity of the NEXAFS resonances depends on the nature and filling of the molecular orbitals and on the included angle between the electric field vector of the X-rays E⃗ and the direction of the valence orbital . The use of nearly linearly polarized light produced by a synchrotron enables one to access the orientation of chain segments near the surface.…”

Section: Introductionmentioning

confidence: 99%

X-PEEM Study on Surface Orientation of Stylized and Rubbed Polyimides

Cossy-Favre

Dı́az

et al. 1998

Macromolecules

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X-ray photoelectron emission microscopy (X-PEEM) was used to study the surface orientation of stylized and rubbed polyimide thin films. Using soft X-rays produced by a synchrotron light source, this technique combines high spatial resolution imaging with near-edge X-ray absorption fine structure (NEXAFS) spectroscopy to yield information on the surface orientation of the films. Stylizing is an ideal model of the rubbing process since the local stress acting on the polyimide to orient the molecules can be calculated. The minimum normal stress necessary to orient the surface of BPDA-PDA films was found to be 45 MPa much lower than the bulk yield stress of 200-300 MPa. Studies of the polyimide films oriented by the conventional rubbing method showed lateral inhomogeneities in the orientation of the polymer at the surface.

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“…One would hope that this fruitful cross-fertilization will continue for quite a while. Even PEEMs are utilized for the characterization of polymer surfaces 24 and biological samples 25 and cross-fertilization between complementary x-ray microscopy approaches is taking place. Since X-ray microscopy is a relatively young field, there are still quite a few things that can be learned from the wider microscopy community.…”

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History and Cross-Disciplinary Perspective of Compositional Imaging and Mapping With Nexafs Microscopy

Ade

1998

Microsc Microanal

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In Near Edge X-ray Absorption Fine Structure (NEXAFS) microscopy, excitations of core electrons into unoccupied molecular orbitals or electronic states provide sensitivity to a wide variety of chemical functionalities in molecules and solids. This sensitivity complements infrared (IR) spectroscopy, although the NEXAFS spectra are not quite as specific and “rich” as IR spectra. The sensitivity of NEXAFS to distinguish chemical bonds and electronic structures covers a wide variety of samples: from metals to inorganics and organics. (There is a tendency in the community to use the term NEXAFS for soft x-ray spectroscopy of organic materials, while for inorganic materials or at higher energies X-ray Absorption Near Edge Spectroscopy (XANES) is utilized, even though the fundamental physics is the same.) The sensitivity of NEXAFS is particularly high to distinguish saturated from unsaturated bonds. NEXAFS can also detect conjugation in a molecule, as well as chemical shifts due to heteroatoms.

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Photoelectron Emission Microscopy and its Application to the Study of Polymer Surfaces

Cited by 10 publications

References 10 publications

Bulk and surface characterization of a dewetting thin film polymer bilayer

Bulk and surface characterization of a dewetting thin film polymer bilayer

X-PEEM Study on Surface Orientation of Stylized and Rubbed Polyimides

History and Cross-Disciplinary Perspective of Compositional Imaging and Mapping With Nexafs Microscopy

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