Asymmetrical plasmon reflections in tapered graphene ribbons with wrinkle edges

Asymmetrical graphene plasmon reflection patterns are found in infrared near-field images of tapered graphene ribbons epitaxially grown on silicon carbon substrates. Comparing experimental data with numerical simulations, the asymmetry of these patterns is attributed to reflection of plasmons by wrinkled edges naturally grown in the graphene. These graphene wrinkles are additional plasmon reflectors with varying optical conductivity, which act as nanometer scale plasmonic modulators and thus have potential applications in photoelectric information detectors, transmitters, and modulators.     

双波长荧光法同时测定水溶解态的茚、萘和菲

建立了一种同时测定水体中多组分溶解态多环芳烃的新方法。为消除共存组分干扰,利用三维荧光谱确定茚、萘和菲的最佳测量点为A(λex250.0nm,λem308.0nm)、B(λex225.0nm,λem335.0nm)、C(λex250.0nm,λem364.0nm);萘和菲相应的最佳参比波长分别为292.5nm和286.7nm,所建方法用于水体中茚、萘和菲的同时测定。其线性范围分别为:2.00×10-7～2.00×10-5mol/L、5.00×10-8～3.50×10-6mol/L和1.00×10-8～1.00×10-6mol/L;检出限分别为:8.63×10-9、1.01×10-8和5.29×10-10mol/L;相对标准偏差分别为:1.1%、1.0%和0.7%(n=7)。方法用于自来水样和海水样的测定,结果满意。     

Circular dichroism spectra of α -lactose molecular measured by terahertz time-domain spectroscopy

Researchers have long studied circular dichroism (CD) for its enormous prospects in life sciences. Many biomolecules have vibration modes in the terahertz region, and terahertz CD spectra are robust to detect biomolecular structures. However, few studies explore the terahertz CD spectra on even natural materials due to technical challenges in both fields. Here, we report a setup of home-built terahertz time-domain spectroscopy to measure the polarization states of terahertz waves. By carefully measuring the transmission Jones matrix, we obtain terahertz CD spectra of α -lactose tablets and D-glucose tablets. Our results show that the terahertz CD spectra are sensitive to vibrational motions in biochemical compounds, which will find wide applications in biosensing and biomedical diagnostics.     

二维极化激元学近场研究进展

极化激元学可以实现纳米尺度上的光子操控和光与物质相互作用的调控,已经成为现代物理学中的一个重要分支.与传统贵金属相比,二维范德瓦耳斯原子晶体中极化激元具有更强的局域能力且可实现主观调控.近期,利用扫描式近场光学显微镜在二维体系中观察到了多种类型的极化激元,为今后量子物理和纳米光子学的发展提供了新思路.本文主要介绍通过近场光学手段揭示二维极化激元学的重要进展和实验结果.在介绍近场光学及其成像原理的基础上,总结了二维极化激元学中近场研究进展的几个重要研究方向,包括等离极化激元、声子极化激元、激子极化激元和杂化型极化激元等.最后提出了近场光学今后可能的发展方向.     

Nano-infrared imaging of localized plasmons in graphene nano-resonators

We conduct in-situ near-field imaging of propagating and localized plasmons(cavity and dipole modes) in graphene nano-resonator. Compared with propagating graphene plasmons, the localized modes show twofold near-field amplitude and high volume confining ability(~ 10~6). The cavity resonance and dipole mode of graphene plasmons can be effectively controlled through optical method. Furthermore, our numerical simulation shows quantitative agreement with experimental measurements. The results provide insights into the nature of localized graphene plasmons and demonstrate a new way to study the localization of polaritons in Van der Waals materials.     

基于扫描探针技术的超分辨光学成像和谱学研究进展

通过对光与物质相互作用产生的各种效应的研究可以获得物质的组分、结构、电学、力学、相互作用等信息,因此光学激发和探测技术成为现代科学研究的重要工具。然而衍射效应将光学探测的最小空间尺度约束在波长量级,这严重限制了光学对微观结构的探测。近年来基于扫描探针显微镜发展而来的近场光学显微镜利用光学天线对光场的局域和增强作用,将光学探测的分辨率推进到10 nm的尺度。文章将介绍目前一种主流的光学超分辨技术——散射式扫描近场光学显微镜及其在材料科学和生命科学方面的前沿研究进展。