CuCl团簇组装薄膜的荧光红移现象

利用气相蒸发技术成功的制备了两个ＣｕＣｌ团簇薄膜样品．ＣｕＣｌ团簇被沉积到单晶Ｓｉ和石英衬底上，然后覆盖一层ＮａＣｌ以防氧化．通过透射电镜和选区衍射观察得知，两个样品主要由ＣｕＣｌ纳米晶和少量的Ｃｕ聚集体构成，其中ＣｕＣｌ纳米晶的直径分别约为３ｎｍ和６ｎｍ；通过室温下测得的光吸收和荧光光谱，发现ＣｕＣｌ激子吸收峰并未出现，而荧光峰向低能方向移动，这可能是激子声子强相互作用引起的结果．在７７Ｋ温度观察到由激子声子耦合而展宽的荧光峰，其峰值近似与量子限制模型的计算结果一致，同时观察到来自陷阱态的宽峰．通过比较３００Ｋ温度下激子荧光峰的展宽和红移量，发现团簇尺寸小的薄膜样品（３ｎｍ）中激子声子相互作用更强，这与理论预测定性一致

Fluorescence red shift of the thin films composed of CuCl clusters

We have successfully prepared two thin films assembled from CuCl clusters.The CuCl clusters were deposited on monocrystalline silicon and quartz substrates and then coated with a layer of NaCl for prevention of the CuCl clusters from oxidation.The two samples consist of CuCl nanocrystals and Cu aggregates and the mean diameters are about 3nm and 6nm by transmission electron microscope and selected area diffraction.From the absorption and fluorescence spectra of the two samples carried out at 300K,we found that the peaks of excition absorption do not show up and luminescence peaks shift to lower energies,possibly due to the strong coupling between exciton and phonon.At 77K,the fluorescence peaks of excitons broadence by exciton phonon coupling have been observed,in approximate agreement with the values calculated by the quantum confinement model.The broad peaks of emission from trapped states or bands have also been observed.In addition,the interaction between exciton and phonon is stronger in the sample with mean diameter about 3nm according to a larger broadening and red shift of the fluorescence peak from excitons,in qualitative agreement with theoretical prediction.