Robust and high-sensitivity thermal probing at the nanoscale based on resonance Raman ratio (R3)
Robust and high-sensitivity thermal probing at the nanoscale based on resonance Raman ratio (R3)
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DOI：
10.1088/2631-7990/ac6cb1
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发表时间：
2022-09-01
影响因子：
14.7
通讯作者：
Wang, Xinwei
中科院分区：
文献类型：
--
作者：
Zobeiri, Hamidreza;Hunter, Nicholas;Wang, Xinwei
基于拉曼光谱的温度传感通常跟踪拉曼波数、线宽和强度的变化，近十年来在表征纳米材料中的能量和电荷输运方面得到了非常广泛的应用。这些拉曼性质的温度系数高度依赖于材料，并受到局部光学散射的影响。因此，基于拉曼的温度传感通常存在较大的不确定性和较低的灵敏度。本文提出了一种基于双共振拉曼现象的新方法，可以精确测量纳米材料（本文为纳米WS2薄膜）从170到470 K的绝对温升。采用532 nm激光（光子能量2.33 eV）进行拉曼实验。在接近室温的温度下，其光子能量与WS2的激子跃迁能非常接近。引入共振拉曼比(R3) ω = I-A1g/I-E2g参数，结合温度对A（1g）和E-2g模式共振拉曼散射的影响。Omega从177到477 K的变化超过两个数量级，这种变化与薄膜厚度和局部光散射无关。结果表明，当ω变化1%时，低温和高温下的温度探测灵敏度分别为0.42 K和1.16 K。基于Omega，我们使用能量输运态分辨拉曼（ET-Raman）测量了类似于25 nm厚悬浮WS2薄膜的面内导热系数(k)。当温度从170 k升高到470 k时，k从50.0下降到20.0 Wm(-1) k -1。这与先前的实验和理论结果以及我们的eet -拉曼测量数据一致。R3技术为纳米材料的温度探测提供了一种非常可靠和高灵敏度的方法，将在纳米级热输运表征、非破坏性评估和制造监控方面有广泛的应用。
Raman spectroscopy-based temperature sensing usually tracks the change of Raman wavenumber, linewidth and intensity, and has found very broad applications in characterizing the energy and charge transport in nanomaterials over the last decade. The temperature coefficients of these Raman properties are highly material-dependent, and are subjected to local optical scattering influence. As a result, Raman-based temperature sensing usually suffers quite large uncertainties and has low sensitivity. Here, a novel method based on dual resonance Raman phenomenon is developed to precisely measure the absolute temperature rise of nanomaterial (nm WS2 film in this work) from 170 to 470 K. A 532 nm laser (2.33 eV photon energy) is used to conduct the Raman experiment. Its photon energy is very close to the excitonic transition energy of WS2 at temperatures close to room temperature. A parameter, termed resonance Raman ratio (R3) Omega = I-A1g/I-E2g , is introduced to combine the temperature effects on resonance Raman scattering for the A(1g) and E-2g modes. Omega has a change of more than two orders of magnitude from 177 to 477 K, and such change is independent of film thickness and local optical scattering. It is shown that when Omega is varied by 1%, the temperature probing sensitivity is 0.42 K and 1.16 K at low and high temperatures, respectively. Based on Omega, the in-plane thermal conductivity (k) of a similar to 25 nm-thick suspended WS2 film is measured using our energy transport state-resolved Raman (ET-Raman). k is found decreasing from 50.0 to 20.0 Wm(-1) K-1 when temperature increases from 170 to 470 K. This agrees with previous experimental and theoretical results and the measurement data using our EET-Raman. The R3 technique provides a very robust and high-sensitivity method for temperature probing of nanomaterials and will have broad applications in nanoscale thermal transport characterization, non-destructive evaluation, and manufacturing monitoring.