摘要
利用光致发光谱(Photoluminescence,PL)、X射线吸收精细结构(X-ray Absorption Fine Structure,XAFS)和MALDI-TOF质谱等技术研究了化学还原法合成的Cu金属纳米团簇的发光性能及其结构。PL谱表明随着反应溶液中十二硫醇(C12SH)和2-巯基-5-正丙烷基嘧啶(C7H10N2S,2-mercapto-5-n-propylpyrimidine,MPP)配体比例的增加,Cu纳米团簇主发光峰的波长从618 nm逐渐蓝移到571 nm。质谱的结果说明以MPP作为单一配体时的主要产物为Cu5[MPP]3;而当为MPP与C12SH两种混合配体时,Cu纳米团簇中Cu原子数变小,组成变为Cu4[MPP][C12SH];并且随着C12SH比例增加,Cu4[MPP][C12SH]产物的组成保持不变。XAFS结果则进一步表明随着C12SH比例的增加,Cu纳米团簇的Cu-S键长从0.228 nm缩短到0.224 nm,原子构型从双三角锥结构转变为四面体。综合以上结果,认为Cu纳米团簇的原子数的减少导致团簇的光致发光从618nm蓝移至597 nm;而Cu-S键长的缩短引起Cu(I)-S杂化的HOMO-LUMO带隙增大,从而导致团簇的发光波长进一步从597 nm蓝移至571 nm。
Background： During the past few decades, metal nanoclusters have received considerable research interests for their distinct optical, catalytic and electronic properties. However, till today, most studies are focused on the synthesis, structure and properties of Au and Ag clusters, while the studies on Cu nanoclusters are rather rare because of its inherent instability. Purpose： We aim to synthesize the Cu nanocluster that has the tunable photoluminescence. Methods： Through varying the initial legend molar ratio of 2-mercapto-5-n-propylpyrimidine and dodecanethiol, a series of Cu nanoclusters with different emission wavelength were prepared. The photoluminescence property and structure of these nanoclusters were studied by the photoluminescence spectrometry（PL）, X-ray absorption fine structure（XAFS） and Matrix Assisted Laser Desorption Ionization Time of Flight Spectrometer（MALDI-TOF） mass spectrometry. Results：（1） PL spectra showed that with the increase of the proportion of dodecanethiol, the maximum emission wavelength of Cu nanoclusters shifted from 618 nm to 571 nm.（2） Mass spectra results indicated that the main products were changed from Cu5MPP3（MPP： 2-mercapto-5-n-propylpyrimidine） in the presence of MPP alone to Cu4[MPP][C12SH] when the dodecanethiol was introduced, and remains unchanged with increasing the dodecanethiol.（3） XAFS results showed that with the increase of dodecanethiol, the Cu-S bond length was shortened from 0.228 nm to 0.224 nm. Conclusion： The reduction of the amount of Cu atomic number would lead to the shift of emission wavelength from 618 nm to 597 nm, and the shortening of Cu-S bond length pushed down the HOMO level which was formed by the Cu（I）-S. With the increase of the HOMO-LUMO band gap, the emission wavelength of the products shifted from 597 nm to 571 nm.
出处
《核技术》
CAS
CSCD
北大核心
2014年第9期17-22,共6页
Nuclear Techniques
基金
国家自然科学基金课题(No.11079032
No.U1232132)资助
关键词
Cu纳米团簇
发光可调
X射线吸收精细结构(XAFS)
同步辐射
Copper nanoclusters, Tunable photoluminescence, X-ray absorption fine structure （XAFS）, Synchrotronradiation
