Schörner Christian, Motamen Sajedeh, Simon Laurent, Reiter Günter, Hildner Richard
Soft Matter Spectroscopy, University of Bayreuth, Universitätsstr. 30, 95447 Bayreuth, Germany.
Institute of Physics, University of Freiburg, Hermann-Herder-Strasse 3, Freiburg 79104, Germany.
ACS Omega. 2018 Jun 20;3(6):6728-6736. doi: 10.1021/acsomega.8b00811. eCollection 2018 Jun 30.
We employ energy-momentum spectroscopy on isolated organic single crystals with micrometer-sized dimensions. The single crystals are grown from a thiophene-based oligomer and are excellent low-loss active waveguides that support multiple guided modes. Excitation of the crystals with a diffraction-limited laser spot results in emission into guided modes as well as into quasi-discrete radiation modes. These radiation modes are mapped in energy-momentum space and give rise to dispersive interference patterns. On the basis of the known geometry of the crystals, especially the height, the characteristics of the interference maxima allow one to determine the energy dependence of two components of the anisotropic complex refractive index. Moreover, the method is suited to identify the orientation of molecules within (and around) a crystalline structure.
我们对尺寸为微米级的孤立有机单晶进行能量动量光谱分析。这些单晶由基于噻吩的低聚物生长而成，是支持多种导模的优异低损耗有源波导。用衍射极限激光光斑激发晶体，会导致发射到导模以及准离散辐射模中。这些辐射模在能量动量空间中被映射，并产生色散干涉图样。基于晶体的已知几何形状，特别是高度，干涉极大值的特征使人们能够确定各向异性复折射率两个分量的能量依赖性。此外，该方法适用于识别晶体结构内部（及周围）分子的取向。
