Photoacoustic FT-IR depth imaging of polymeric surfaces : overcoming IR diffraction limits
It is well established that the photoacoustic effect based on absorption of electromagnetic radiation into thermal waves allows surface depth profiling. However, limited knowledge exists concerning its spatial resolution. The spiral-stepwise (SSW) approach combined with phase rotational analysis is...
| Veröffentlicht in: | Langmuir : the ACS journal of surfaces and colloids. - 1992. - 20(2004), 24 vom: 23. Nov., Seite 10691-9 |
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| Format: | Aufsatz |
| Sprache: | English |
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2004
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| Zugriff auf das übergeordnete Werk: | Langmuir : the ACS journal of surfaces and colloids |
| Schlagworte: | Journal Article Research Support, U.S. Gov't, Non-P.H.S. Polymers |
| Zusammenfassung: | It is well established that the photoacoustic effect based on absorption of electromagnetic radiation into thermal waves allows surface depth profiling. However, limited knowledge exists concerning its spatial resolution. The spiral-stepwise (SSW) approach combined with phase rotational analysis is utilized to determine surface depth profiling of homogeneous and nonhomogeneous multilayered polymeric surfaces in a step-scan photoacoustic FT-IR experiment. In this approach, the thermal wave propagating to the surface is represented as the integral of all heat wave vectors propagating across the sampling depth xn, and the spiral function K'beta(lambda)e(-beta)(lambda)xne(-x)n/mu(th)e(i)(omegat-(xn/mu(th))) represents the amplitude and phase of the heat wave vector propagating to the surface. The SSW approach can be applied to heterogeneous surfaces by representing thermal waves propagating to the surface as the sum of the thermal waves propagating through homogeneous layers that are integrals of all heat vectors from a given sampling depth. The proposed model is tested on multilayered polymeric surfaces and shows that the SSW approach allows semiquantitative surface imaging with the spatial resolution ranging from micrometer to 500 nm levels, and the spatial resolution is a function of the penetration depth |
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| Beschreibung: | Date Completed 24.04.2006 Date Revised 15.11.2006 published: Print Citation Status MEDLINE |
| ISSN: | 1520-5827 |