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

本文用荧光光谱法研究了有机分子组装体引起的晶体核仁形成的初始过程。使用三甲基-（2-氧代-2-芘-1-基-乙基）-溴化铵（PyAm）作为荧光染料分子。聚乙烯醇薄膜中PyAm聚集体的尺寸随着染料浓度的增加而增加。当PyAm浓度较低（0.001mol%）时，其荧光光谱仅显示单体发射。随着染料浓度的增加，荧光峰向红色移动，这被归因于二聚体或准分子样发射。荧光光谱的变化与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出取决于畴大小的荧光性质的分级变化（类似于连续反应）。我们还发现PyAm纳米聚集体的荧光光谱在光照下发生了变化。它起源于PyAm聚集体的光诱导溶解。

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.