Piszter Gábor, Kertész Krisztián, Bálint Zsolt, Biró László Péter
Institute of Technical Physics and Materials Science, Centre for Energy Research, PO Box 49, 1525 Budapest, Hungary.
Department of Zoology, Hungarian Natural History Museum, 13 Baross St., 1088 Budapest, Hungary.
R Soc Open Sci. 2023 Apr 5;10(4):221487. doi: 10.1098/rsos.221487. eCollection 2023 Apr.
The iridescent structural colours of butterflies, generated by photonic nanoarchitectures, often function as species-specific sexual signals; therefore, they are reproduced precisely from generation to generation. The wing scales of oakblue hairstreak butterflies (genus , Theclinae, Lycaenidae, Lepidoptera) contain multi-layer photonic nanoarchitectures, which can generate a wide range of structural colours, from violet to green. By scanning (SEM) and cross-sectional transmission electron microscopy (TEM) investigation, the colour tuning mechanism of the cover scales was explored. We revealed that the characteristic size change of structural elements in similar photonic nanoarchitectures led to different structural colours that were examined by various reflectance spectrophotometry techniques. The measured structural properties of the naturally tuned photonic nanoarchitectures were used to calculate wing reflectances, which were compared with the measurement results. We found that the simulated structural colours were systematically redshifted by 95-126 nm as compared with the measured normal-incidence reflectance results. This is attributed to the swelling of the chitinous multi-layer structures during the standard TEM sample preparation and the tilt of the cover scales, which both affect the apparent layer thicknesses in the TEM cross-sections. We proposed a simulation correction and compared the results with the layer thicknesses measured on cryogenically prepared non-embedded SEM cross-sections.
蝴蝶由光子纳米结构产生的彩虹色结构色，通常作为物种特异性的性信号发挥作用；因此，它们代代精确重现。栎蓝小灰蝶（鳞翅目灰蝶科线灰蝶亚科）的翅鳞片含有多层光子纳米结构，可产生从紫色到绿色的多种结构色。通过扫描电子显微镜（SEM）和横截面透射电子显微镜（TEM）研究，探索了覆盖鳞片的颜色调节机制。我们发现，类似光子纳米结构中结构元素的特征尺寸变化导致了不同的结构色，这些结构色通过各种反射分光光度法技术进行了检测。利用自然调节的光子纳米结构的测量结构特性来计算翅膀反射率，并与测量结果进行比较。我们发现，与测量的垂直入射反射率结果相比，模拟的结构色系统性地红移了95 - 126纳米。这归因于在标准TEM样品制备过程中几丁质多层结构的膨胀以及覆盖鳞片的倾斜，这两者都会影响TEM横截面中的表观层厚度。我们提出了一种模拟校正方法，并将结果与在低温制备的非嵌入式SEM横截面中测量的层厚度进行了比较。
