Surface second harmonic generation from asymmetric multilayer assemblies: Gaining insight into layer-dependent order
Surface second harmonic generation from asymmetric multilayer assemblies: Gaining insight into layer-dependent order
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DOI：
10.1021/la0101503
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发表时间：
2001-05-29
期刊：
影响因子：
3.9
通讯作者：
Blanchard, GJ
中科院分区：
文献类型：
--
作者：
Bakiamoh, SB;Blanchard, GJ
我们报告了使用表面二次谐波发生（SHG）测量来探测不对称结合的脂肪族多层组件中的微观组织。使用金属离子配位化学不对称结合的层可以控制各个层成分的方向，并且不对称配位使组件具有chi（（2））活性。我们发现，对于我们在此报告的系统，表面二阶非线性响应最初与层数的平方成比例增加，然后随着附加的 adlayers 饱和并减小。光学零椭偏仪和 FTIR 数据表明厚度和发色团密度有规律地增长，而表面 SHG 数据表明随着附加层的吸附，无序度不断增加。 FTIR 数据表明，随着层数的增加，这些链的整体有序度略有下降，但这种趋势并不像表面倍频数据中看到的那么明显。我们在非线性发色团取向分布随层生长增加而不是平均取向角变化的背景下解释这些数据。
We report on the use of surface second harmonic generation (SHG) measurements to probe microscopic organization in asymmetrically bound aliphatic multilayer assemblies. The use of layers that are bound asymmetrically using metal ion coordination chemistry allows the orientation of the individual layer constituents to be controlled, and the asymmetric coordination makes the assemblies chi ((2))-active. We find that, for the systems we report here, the surface second-order nonlinear response increases in proportion to the square of the number of layers initially and then saturates and decreases with additional adlayers. Optical null ellipsometry and FTIR data point to regular growth in terms of thickness and chromophore density, and the surface SHG data point to increasing disorder with the adsorption of additional layers. The FTIR data suggest a subtle decrease in overall order of these chains with increasing number of layers, but this trend is not as pronounced as that seen in the surface SHG data. We interpret these data in the context of an increase in the distribution of nonlinear chromophore orientations with layer growth and not a change in the average orientation angle.