Department of Chemistry, The City College of New York, New York, N.Y. 10031, USA.
J Chem Phys. 2011 Jan 14;134(2):024707. doi: 10.1063/1.3523646.
We obtain the surface enhanced Raman spectra of 4-mercaptopyridine on lead sulfide (PbS) quantum dots as a function of nanoparticle size and excitation wavelength. The nanoparticle radii are selected to be less than the exciton Bohr radius of PbS, enabling the observation of quantum confinement effects on the spectrum. We utilize the variation of nontotally symmetric modes of both b(1) and b(2) symmetry as compared to the totally symmetric a(1) modes to measure the degree of charge-transfer between the molecule and quantum dot. We find both size dependent and wavelength dependent resonances in the range of these measurements, and attribute them to charge-transfer resonances which are responsible for the Raman enhancement.
我们获得了 4-巯基吡啶在硫化铅（PbS）量子点上的表面增强拉曼光谱，作为纳米粒子尺寸和激发波长的函数。选择纳米粒子半径小于 PbS 的激子玻尔半径，从而能够观察到光谱上的量子限制效应。我们利用与完全对称的 a(1)模式相比，b(1)和 b(2)对称的非完全对称模式的变化来测量分子和量子点之间的电荷转移程度。我们在这些测量范围内发现了尺寸相关和波长相关的共振，并将其归因于电荷转移共振，这是拉曼增强的原因。
