It is crucial to understand the behavior of the optical properties of soot in the visible and near-IR spectral range to calculate the magnitude of their emission and absorption. Such information also helps in the development of diagnostic methods for soot. We measured the absolute value of the refractive index functions of soot nanoparticles E(m,1064) at a wavelength of 1064 nm, as well as the ratio of the refractive index functions at laser wavelengths of 532 nm and 1064 nm in a premixed ethylene/air flame using laser-induced incandescence. E(m,1064) increased with the flame height from 0.29 to 0.43. Depending on the height above the burner, the ratio of E(m,1064)/E(m,532) increased from 0.88 to 1. These changes in the optical properties are attributed to differences in the soot structure, such as the different sizes of graphene planes, which increased from 0.96 to 1.24 nm as the height above the burner increased from 10 to 20 mm. The presented data provide comprehensive information about the optical properties of soot in a premixed ethylene/air flame according to the height above a burner and make it possible to compare measurements of the soot optical properties in various target flames.

中文翻译：

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烟灰折射率函数沿预混乙烯/空气火焰高度的变化及其与烟灰结构的相关性

了解烟尘在可见光和近红外光谱范围内的光学特性的行为以计算其发射和吸收的幅度至关重要。这些信息还有助于开发烟尘诊断方法。我们测量了烟灰纳米粒子 E(m,1064) 在 1064 nm 波长下的折射率函数的绝对值，以及在 532 nm 和 1064 nm 激光波长下在预混乙烯/使用激光诱导白炽的空气火焰。E(m,1064)随着火焰高度从0.29增加到0.43而增加。根据燃烧器上方的高度，E(m,1064)/E(m,532) 的比率从 0.88 增加到 1。光学特性的这些变化归因于烟尘结构的差异，例如不同的尺寸石墨烯平面，随着燃烧器上方的高度从 10 增加到 20 毫米，它从 0.96 增加到 1.24 纳米。所提供的数据根据​​燃烧器上方的高度提供了有关预混乙烯/空气火焰中烟灰光学特性的综合信息，并且可以比较各种目标火焰中烟灰光学特性的测量结果。