Measuring the orientation of a single fluorescent nanoemitter and obtaining emitters with a desired orientation is of highest importance for nanophotonics, especially in plasmonics where an emitting dipole close to a metallic surface will couple efficiently to plasmonic modes only if it is deposited vertically. Control of the orientation of a nano-object remains a challenge. Achieving vertical orientation, or having an information on the dipole orientation are key steps for efficient plasmonic excitation. We consider here cubic-shaped nanoplatelets with a thin CdSe core sandwiched in a thick CdS shell. By a combination of polarization measurement and radiation pattern Fourier analysis, we show that each single platelet behaves with excellent precision as a 2D dipole (sum of 2 orthogonal incoherent dipoles) and having only two possible orientations: either they lie horizontally on the substrate or they stand vertically on the edge. The cubic shape allows some platelets to deposit vertically so that they present a deterministic vertical dipole component.

中文翻译：

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探测具有垂直或水平方向的单立方CdSe / CdS纳米血小板的荧光偶极子

对于纳米光子学来说，测量单个荧光纳米发射体的取向并获得具有所需取向的发射体是最重要的，特别是在等离子激元中，靠近金属表面的发射偶极子只有垂直沉积才能有效地耦合到等离激元模式。纳米物体取向的控制仍然是一个挑战。实现垂直方向或获得有关偶极子方向的信息是有效等离激元激发的关键步骤。我们在这里考虑的是立方立方体形的纳米薄片，其薄CdSe核夹在厚CdS壳中。通过极化测量和辐射方向图傅立叶分析的组合，我们显示出每个单个血小板作为2D偶极子（2个正交非相干偶极子的总和）的行为具有极好的精度，并且只有两个可能的方向：它们要么水平放置在基材上，要么垂直放置在边缘上。立方体形状允许一些血小板垂直沉积，因此它们具有确定性的垂直偶极子分量。