Martínez Martínez V, López Arbeloa F, Bañuelos Prieto J, López Arbeloa I
Departamento de Química Física, Universidad del País Vasco-EHU, Apartado 644, 48080-Bilbao, Spain.
J Phys Chem B. 2005 Apr 21;109(15):7443-50. doi: 10.1021/jp050440i.
The photoluminescence response of Rhodamine 6G (R6G) laser dye intercalated into solid thin films of Laponite (Lap) clay is studied as a function of dye loading. Fluorescence spectroscopy (steady-state and time-resolved techniques) was used to characterize the R6G species adsorbed into the solid films. For very diluted R6G loadings (</=0.1% CEC, i.e., the percentage of the total cation exchange capacity of Lap) the fluorescence properties of R6G monomer were characterized, which presents an emission band centered at 548 nm, an average lifetime of 4.2 ns, and a fluorescence efficiency higher than that of the R6G monomer in liquid solution. By increasing the loading, dye molecules tend to self-aggregate, and different dimers are formed in moderate dye concentrations (in the 1-25% CEC range): oblique head-to tail J-type dimers, with weak emission bands at around 575 nm; and sandwich H-type dimers, as efficient quenchers of the fluorescent emission. Higher-order aggregates of R6G in Lap films are formed in high loading samples (>40% CEC), with a reminiscent fluorescence band at around 600 nm.
研究了插入锂皂石（Lap）粘土固体薄膜中的罗丹明6G（R6G）激光染料的光致发光响应与染料负载量的关系。采用荧光光谱法（稳态和时间分辨技术）对吸附在固体薄膜中的R6G物种进行表征。对于非常稀释的R6G负载量（≤0.1%阳离子交换容量，即Lap总阳离子交换容量的百分比），表征了R6G单体的荧光特性，其发射带中心位于548nm，平均寿命为4.2ns，荧光效率高于其在液体溶液中的荧光效率。随着负载量的增加，染料分子倾向于自聚集，在中等染料浓度（1-25%阳离子交换容量范围内）形成不同的二聚体：斜头对尾J型二聚体，在575nm左右有弱发射带；以及夹心H型二聚体，作为荧光发射的有效猝灭剂。在高负载样品（>40%阳离子交换容量）中形成了Lap薄膜中R6G的高阶聚集体，在600nm左右有一个类似的荧光带。
