金芯的表面形态控制在等离子体纳米matryoshkas中的空心或桥接纳米缺口的形成和他们的SERS反应。,The Journal of Physical Chemistry C

当前位置： X-MOL 学术 › J. Phys. Chem. C › 论文详情

Our official English website, www.x-mol.net, welcomes your feedback! (Note: you will need to create a separate account there.)

金芯的表面形态控制在等离子体纳米matryoshkas中的空心或桥接纳米缺口的形成和他们的SERS反应。
The Journal of Physical Chemistry C ( IF 3.3 ) Pub Date : 2016-07-11 00:00:00 , DOI: 10.1021/acs.jpcc.6b03606
Boris N. Khlebtsov ₁ , Nikolai G. Khlebtsov _{1,

2}

Affiliation

表面增强拉曼散射（SERS）探针在Au核和壳之间具有纳米级的内部间隙，也称为nanomatryoshkas（NMs），对基于SERS的生物成像和生物传感引起了极大的兴趣。最近，已经证明种子介导的生长对于NM合成是有效的。我们发现金纳米管内的纳米间隙的结构在很大程度上取决于核心表面形态。具体而言，当最初的柠檬酸盐稳定的15和35 nm光滑Au核在十六烷基三甲基氯化铵（CTAC）存在下用1,4-苯二硫醇（BDT）进一步官能化时，Au壳的生长导致形成亚纳米级的中空内部含BDT分子的缺口。相比之下，使用23和35 nm的多面多边形CTAC稳定的Au核进行Au壳层的生长会导致NM带有较小的桥接间隙。对于23 nm的多边形核，也观察到不完整的外壳的形成，该外壳具有一个或两个纳米级的中空间隙，而对于35 nm的核，则没有观察到。BDT分子在桥状间隙NM中的实验性SERS响应要比中空间隙NM高一个数量级。这一发现与有限差分时域（FDTD）模拟相一致，该模拟预测与空心间隙NM相比，纳米桥接间隙内部的电磁场更强。两种类型（两种尺寸，四个样品）的NM中来自BDT的主要SERS峰比使用BDT表面功能化后单独记录的相应15CIT，23CTAC，35CIT和35CTAC核的近场SERS峰高一个数量级。分子。这个观察结果是通过简单的偶极近似（DA）理论来解释的，通过与精确的多层Mie（ML Mie）计算进行比较，证实了该方法的开发是为了以良好的准确性估算中空间隙NM中与结构和波长相关的电磁SERS增强。随着核心尺寸的两倍增加，NM SERS响应也增加了，较大和较小NM的主峰强度之比约为2。最后，计算出的中空间隙NM的SERS光谱与数据相符报道了532、633和785 nm的激光激发。从这项研究中获得的物理见解为基于等离子纳米结构内亚纳米间隙中的电磁场增强的新型SERS平台进行合理设计和有效优化开辟了道路。通过与精确的多层Mie（ML Mie）计算进行比较来确认。随着核心尺寸的两倍增加，NM SERS响应也增加，较大和较小NM的主峰强度之比约为2。最后，计算出的中空间隙NM的SERS光谱与数据相符报道了532、633和785 nm的激光激发。从这项研究中获得的物理见解为基于等离子纳米结构内亚纳米间隙中的电磁场增强的新型SERS平台进行合理设计和有效优化开辟了道路。通过与精确的多层Mie（ML Mie）计算进行比较来确认。随着核心尺寸的两倍增加，NM SERS响应也增加，较大和较小NM的主峰强度之比约为2。最后，计算出的中空间隙NM的SERS光谱与数据相符报道了532、633和785 nm的激光激发。从这项研究中获得的物理见解为基于等离子纳米结构内亚纳米间隙中的电磁场增强的新型SERS平台的合理设计和有效优化开辟了道路。最后，计算出的中空间隙NM的SERS光谱与报告的532、633和785 nm激光激发的数据一致。从这项研究中获得的物理见解为基于等离子纳米结构内亚纳米间隙中的电磁场增强的新型SERS平台的合理设计和有效优化开辟了道路。最后，计算出的中空间隙NM的SERS光谱与报告的532、633和785 nm激光激发的数据一致。从这项研究中获得的物理见解为基于等离子纳米结构内亚纳米间隙中的电磁场增强的新型SERS平台的合理设计和有效优化开辟了道路。

"点击查看英文标题和摘要"

Surface Morphology of a Gold Core Controls the Formation of Hollow or Bridged Nanogaps in Plasmonic Nanomatryoshkas and Their SERS Responses

Surface-enhanced Raman scattering (SERS) probes with a nanometer-sized interior gap between the Au core and shell, also called nanomatryoshkas (NMs), have attracted great interest in SERS-based bioimaging and biosensing. Recently, seed-mediated growth has been shown to be effective for NM synthesis. We found that the structure of nanogaps inside Au NMs depends strongly on the core surface morphology. Specifically, when the initially citrate-stabilized 15 and 35 nm smooth Au cores were further functionalized with 1,4-benzenedithiol (BDT) in the presence of cetyltrimethylammonium chloride (CTAC), the Au shell growth led to the formation of a subnanometer hollow interior gap containing BDT molecules. In contrast, the use of 23 and 35 nm faceted polygonal CTAC-stabilized Au cores for Au shell growth resulted in NMs with small bridged gaps. The formation of incomplete outer shells with one or two nanometer-sized hollow gaps was also observed for 23 nm polygonal cores but not for 35 nm ones. The experimental SERS response from BDT molecules in bridged-gap NMs was an order of magnitude higher than that for hollow-gap NMs. This finding is in agreement with the finite-difference time-domain (FDTD) simulations predicting stronger electromagnetic fields inside nanobridged gaps, as compared to hollow-gap NMs. The major SERS peaks from BDT inside NMs of both types (two sizes, four samples) was an order of magnitude higher than the near-field SERS peaks recorded for the corresponding 15CIT, 23CTAC, 35CIT, and 35CTAC cores alone after surface functionalization with BDT molecules. This observation is explained by a simple dipole approximation (DA) theory, which was developed to estimate the structure- and wavelength-dependent electromagnetic SERS enhancement in the hollow-gap NMs with good accuracy, as confirmed by comparison with exact multilayered Mie (ML Mie) calculations. With a double increase in the core size, the NM SERS response also increased, and the ratio between the major peak intensities of the larger and smaller NMs was about 2. Finally, the calculated SERS spectra of the hollow-gap NMs agree with the data reported for 532, 633, and 785 nm laser excitations. The physical insights acquired from this study open the way for rational design and efficient optimization of new SERS platforms based on electromagnetic field enhancement in subnanometer gaps within plasmonic nanostructures.

更新日期：2016-07-11

点击分享查看原文

点击收藏

阅读更多本刊新发论文本刊介绍/投稿指南