We studied the weak fluorescence from the dimer of eosin Y (EY) in aqueous solutions. We used a newly developed ultrathin optical cell with a thickness ranging from of the order of microns to several hundreds of microns to successfully measure the fluorescence spectra of highly concentrated aqueous solutions of EY without artifacts caused by the reabsorption of fluorescence. The spectra we obtained were similar to the fluorescence spectrum of the EY monomer; almost no fluorescence was observed from the EY dimer. By a careful comparison of the spectra of solutions at low and high concentrations of EY, we succeeded in extracting the fluorescence spectrum of the EY dimer. The fluorescence quantum yield of the EY dimer was estimated to be 0.005.

中文翻译：

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估计在水溶液中形成的曙红Y二聚体的弱荧光的量子产率

我们研究了曙红Y（EY）在水溶液中的二聚体产生的弱荧光。我们使用了一种新开发的超薄光学电池，其厚度范围从微米到几百微米不等，可以成功地测量EY的高浓度水溶液的荧光光谱，而不会因荧光的重新吸收而造成伪影。我们获得的光谱类似于EY单体的荧光光谱。EY二聚体几乎没有观察到荧光。通过仔细比较低浓度和高浓度EY溶液的光谱，我们成功地提取了EY二聚体的荧光光谱。EY二聚体的荧光量子产率估计为0.005。