摘要
报道了以飞秒脉冲激光为激发光源的水溶性CdTe量子点(QDs)的稳态荧光光谱和纳秒时间分辨荧光光谱.实验发现CdTe量子点的荧光光谱峰值位置随激发波长变化发生明显移动,激发脉冲波长越长,荧光峰位红移越大.荧光动力学实验数据显示,在400nm和800nm脉冲激光激发下,水溶性CdTe量子点的荧光光谱中均含有激子态和诱捕态两个衰减成分,两者的发射峰相距很近,诱捕态的发射峰波长较长.在800nm脉冲激光激发下的诱捕态成分占总荧光强度的比重比400nm激发下的约高3倍,其相对强度的这种变化导致了稳态荧光发射峰位的红移.
We have used femtosecond laser pulse to investigate the steady-state and nanosecond time-resolved photoluminescence of aqueous CdTe quantum dots （QDs）. Up-conversion luminescences of the CdTe QDs induced by two-photon excitation were observed. Compared with 400 nm excitation, the peak wavelength of photoluminescence induced by 1208 nm excitation was redshifted about 28 nm （88 meV）. The decay kinetics showed a fast and a slow decay component which can be assigned to bandedge excitonic state （3-5 ns ） and surface trapping state （30-50 ns）, respectively. Luminescence and up-conversion luminescence at room temperature showed similar decay kinetics. The relative change of photoluminescence intensity between excitonic and trapping state is responsible for the red shift of emission peak. It was found that the proportion of excitonic emission in whole luminescence at 400 nm excitation is bigger than that of excitonic emission at 800 nm excitation, so with increasing the wavelength of laser excitation steady state spectra have the red shift of emission peaks.
出处
《物理学报》
SCIE
EI
CAS
CSCD
北大核心
2007年第5期2926-2930,共5页
Acta Physica Sinica
基金
国家自然科学基金(批准号:60478015和10674034)资助的课题~~
关键词
CDTE量子点
时间分辨
荧光光谱
上转换荧光
CdTe quantum dots （QDs）, time-resolved, two-photon absorption （TPA）, up-conversion photoluminescence （UCL）
