Overgaag Karin, Liljeroth Peter, Grandidier Bruno, Vanmaekelbergh Daniël
Condensed Matter and Interfaces, Debye Institute, Utrecht University, PO Box 80 000, 3508 TA Utrecht, The Netherlands.
ACS Nano. 2008 Mar;2(3):600-6. doi: 10.1021/nn7003876.
The electronic local density of states (LDOS) of single PbSe quantum dots (QDs) and QD molecules is explored using low-temperature scanning tunneling microscopy (STM) and spectroscopy (STS). Both individual PbSe QDs and molecular aggregates of PbSe QDs (dimers, trimers, etc.) are mechanically stabilized in a two-dimensional superlattice of wide band gap CdSe QDs acting as an inert matrix. The LDOS measured at individual QDs dispersed in the matrix is identical to that of single isolated QDs chemically linked to a substrate. We investigate the degree of quantum mechanical coupling between the PbSe QDs in molecular aggregates by comparing the LDOS measured at each site in the aggregates to that of an individual PbSe QD. We observe a variable broadening of the resonances indicating a spatially dependent degree of electron delocalization in the molecular aggregates.
利用低温扫描隧道显微镜（STM）和光谱学（STS）研究了单个PbSe量子点（QD）和QD分子的电子局域态密度（LDOS）。单个PbSe量子点以及PbSe量子点的分子聚集体（二聚体、三聚体等）在作为惰性基质的宽带隙CdSe量子点的二维超晶格中实现了机械稳定。在分散于基质中的单个量子点处测得的LDOS与化学连接到衬底上的单个孤立量子点的LDOS相同。通过比较在分子聚集体中每个位点测得的LDOS与单个PbSe量子点的LDOS，我们研究了分子聚集体中PbSe量子点之间的量子力学耦合程度。我们观察到共振的可变展宽，这表明分子聚集体中电子离域程度存在空间依赖性。
