Study on initial processes of crystal nucleolus formation as probed by fluorescence spectral change due to the organic molecular assemblies

我们研究了晶体核仁形成的初始过程，通过荧光光谱的变化探测到有机分子的集合。采用三甲基-（2-氧-2-芘-1-基乙基）溴化铵（PyAm）作为荧光染料分子。PVA薄膜中聚集体的大小随染料浓度的增加而增加。在低浓度0.001mol%的PVA薄膜中，PyAm的荧光光谱仅表现为单体发射。随着染料浓度的增加，荧光峰转移到红色，这被分配到二聚体或准分子样发射。荧光光谱的变化与薄膜中聚集体的形成有关。通过相分离形成的纳米晶体和/或聚集体被认为显示荧光性质的层次变化（如连续反应），这取决于畴的大小。我们还发现了光照射下PyAm纳米聚集体的荧光光谱变化。它起源于光诱导的PyAm聚集体溶解。

We have studied on intial processes of crystal nucleolus formation as probed by fluorescence spectral change due to the organic molecular assemblies. Trimethyl-(2-oxo-2-pyrene-1-yl-ethyl)-ammonium bromide (PyAm) was used as a fluorescent dye molecule. The size of PyAm aggregates in the PVA thin films were increased with increasing dye concentration. The fluorescence spectra of PyAm in the PVA film at a lower concentration of 0.001mol% only showed the monomer emission. The fluorescence peak shifted to the red with increasing dye concentration, which was assigned to a dimer or excimer-like emission. Changes in the fluorescence spectra relate to the formation of aggregates in the films. The nano-crystals and/or aggregates formed by phase separation are presumed to show hierarchical change (like a consecutive reaction) of fluorescence property depending on the domain size. We also find the fluorescence spectral change of PyAm nano-aggregates by the photo irradiation. It is originated from the photoinduced dissolution of PyAm aggregates.