The MacDiarmid Institute for Advanced Materials and Nanotechnology, School of Chemical and Physical Sciences, Victoria University of Wellington, PO Box 600, Wellington, 6140, New Zealand.
Phys Chem Chem Phys. 2012 Mar 7;14(9):3219-25. doi: 10.1039/c2cp23853e. Epub 2012 Jan 27.
Single-molecule Surface-Enhanced Raman Scattering (SERS) detection of buckminsterfullerene (C(60)) is achieved by using different isotopologues of the molecule with a distribution around an average isotopic substitution ((12)C → (13)C) of 30%. The distribution of different isotopologues creates a broad (20 cm(-1)) average SERS signal within which single-molecule SERS spectra of individual isotopic realizations of the molecule can be distinguished. The SERS enhancement factors for SM-SERS C(60) events are typically in the range of ~10(8), suggesting a limitation imposed by either photobleaching or surface interactions with the (Ag) metallic colloids to reach the highest SERS hot-spots (which can typically have larger maximum enhancements). SM-SERS signals of isotopically substituted C(60) also show broader peaks (FWHM ≈ 4 cm(-1)) than equivalent signals in natural C(60). The latter feature suggests a contribution to the homogeneous broadening coming from isotopic disorder in the molecule; a feature that can only be observed with the ability to detect single-molecule spectra.
通过使用分子的不同同位素，其平均同位素取代度（（12）C→（13）C）约为 30%，实现了富勒烯（C（60））的单分子表面增强拉曼散射（SERS）检测。不同同位素的分布在平均 SERS 信号中产生了一个宽（20cm（-1））的分布，在该分布中可以区分分子的单个同位素实现的单分子 SERS 光谱。SM-SERS C（60）事件的 SERS 增强因子通常在10（8）的范围内，这表明存在由光漂白或与（Ag）金属胶体的表面相互作用引起的限制，以达到最高的 SERS 热点（通常具有更大的最大增强）。同位素取代的 C（60）的 SM-SERS 信号也显示出比天然 C（60）的等效信号更宽的峰（FWHM≈4cm（-1））。后一个特征表明分子中同位素无序对均匀展宽有贡献；这是只有通过检测单分子光谱才能观察到的特征。
