The near edge X-ray absorption fine structure (NEXAFS) spectra of orthorhombic single crystals of n-octacosane (n-C₂₈H₅₈), recorded at room temperature (298 K) and at cryogenic temperatures (93 K), show distinct differences. The characteristic carbon 1s → σ*_C–H band in the NEXAFS spectrum of n-C₂₈H₅₈ is broader and has a lower-energy onset in its room temperature spectrum than in its NEXAFS spectrum recorded at cryogenic temperatures. Density functional theory simulations show that nuclear motion and molecular disorder contribute to the observed spectral broadness and are the origin of the low-energy onset of the C–H band in the room temperature spectrum

中文翻译：

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正构烷烃NEXAFS光谱中的温度依赖性

在室温（298 K）和低温（93 K）下记录的正辛烷（n- C ₂₈ H ₅₈）的正交各向异性单晶的近边缘X射线吸收精细结构（NEXAFS）光谱显示出明显的差异。n- C ₂₈ H ₅₈的NEXAFS光谱中的特征碳1s→σ* _C–H带比在低温下记录的NEXAFS光谱更宽，并且在室温光谱中的能量发作更低。密度泛函理论模拟表明，核运动和分子紊乱有助于观察到的光谱范围，并且是室温光谱中C–H波段低能发作的起源