Saphiannikova Marina, Geue Thomas M, Henneberg Oliver, Morawetz Knut, Pietsch Ullrich
Institute of Physics, University of Potsdam, PO Box 601553, D-14415, Germany.
J Chem Phys. 2004 Feb 22;120(8):4039-45. doi: 10.1063/1.1642606.
Surface relief gratings on azobenzene containing polymer films were prepared under irradiation by actinic light. Finite element modeling of the inscription process was carried out using linear viscoelastic analysis. It was assumed that under illumination the polymer film undergoes considerable plastification, which reduces its original Young's modulus by at least three orders of magnitude. Force densities of about 10(11) N/m3 were necessary to reproduce the growth of the surface relief grating. It was shown that at large deformations the force of surface tension becomes comparable to the inscription force and therefore plays an essential role in the retardation of the inscription process. In addition to surface profiling the gradual development of an accompanying density grating was predicted for the regime of continuous exposure. Surface grating development under pulselike exposure cannot be explained in the frame of an incompressible fluid model. However, it was easily reproduced using the viscoelastic model with finite compressibility.
含偶氮苯聚合物薄膜上的表面浮雕光栅是在光化光照射下制备的。使用线性粘弹性分析对刻写过程进行了有限元建模。假定在光照下聚合物薄膜会发生显著的塑化，这使其原始杨氏模量降低至少三个数量级。要重现表面浮雕光栅的生长，需要约10(11) N/m3的力密度。结果表明，在大变形时，表面张力与刻写力相当，因此在刻写过程的延迟中起重要作用。除了表面轮廓外，预测在连续曝光情况下会伴随出现密度光栅的逐渐形成。脉冲曝光下的表面光栅形成无法用不可压缩流体模型来解释。然而，使用具有有限可压缩性的粘弹性模型很容易重现这一现象。
