反射(计算机编程)
吸收(声学)
光谱学
材料科学
选择(遗传算法)
光学
入射角(光学)
红外光谱学
吸收光谱法
入射(几何)
红外线的
分析化学(期刊)
化学
物理
计算机科学
环境化学
人工智能
天文
有机化学
程序设计语言
作者
David Rath,Vojtěch Mikerásek,Chunlei Wang,Moritz Eder,Michael Schmid,Ulrike Diebold,Gareth S. Parkinson,Jiří Pavelec
出处
期刊:Cornell University - arXiv
日期:2024-03-28
标识
DOI:10.48550/arxiv.2403.19263
摘要
Infrared Reflection Absorption Spectroscopy (IRAS) on dielectric single crystals is challenging because the optimal incidence angles for light-adsorbate interaction coincide with regions of low IR reflectivity. Here, we introduce an optimized IRAS setup that maximizes the signal-to-noise ratio for non-metals. This is achieved by maximizing light throughput, and by selecting optimal incidence angles that directly impact the peak heights in the spectra. The setup uses a commercial FTIR spectrometer and is usable in ultra-high vacuum (UHV). Specifically, the design features sample illumination and collection mirrors with a high numerical aperture inside the UHV system, and an adjustable aperture to select the incidence angle range on the sample. This is important for p-polarized measurements on dielectrics, because the peaks in the spectra reverse direction at the Brewster angle (band inversion). The system components are connected precisely via a single flange, ensuring long-term stability. We studied the signal-to-noise (SNR) variation in p-polarized IRAS spectra for one monolayer of CO on TiO2(110) as a function of incidence angle range, where a maximum signal-to-noise ratio of 70 was achieved at 4 cm-1 resolution in five minutes measurement time. The capabilities for s-polarization are demonstrated by measuring one monolayer D2O adsorbed on a TiO2(110) surface, where a SNR of 65 was achieved at a delta_R/R0 peak height of 1.4x10-4 in twenty minutes.
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