Critical Raman line shape behavior of fluid nitrogen
Critical Raman line shape behavior of fluid nitrogen
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DOI：
10.1351/pac200476010147
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发表时间：
2004-01
影响因子：
1.8
通讯作者：
M. Musso;F. Matthai;D. Keutel;K. Oehme
中科院分区：
文献类型：
--
作者：
M. Musso;F. Matthai;D. Keutel;K. Oehme
摘要简单分子流体的各向同性拉曼线形在其各自的气液临界点附近表现出临界线的展宽。为了观察到这一现象，给出的振动模的能带位置与密度有关，并且振动去布居过程对谱线展宽的贡献可以忽略不计。特别注意到液氮的各向同性(即非旋转展宽)线形受到相同振子之间共振分子间振动相互作用的影响。通过精心选择的同位素混合物(14N2).975-(14N15N).025，利用最高分辨率的双单色仪和现代电荷耦合器件检测技术，以高达毫开尔文的分辨率，测定了共振耦合的14N2和共振非耦合的14N15N的位移、宽度和不对称性的温度和密度依赖关系，分辨率高达毫开尔文。明确的证据表明，在所研究的所有致密相中都存在振动共振耦合。
Abstract Isotropic Raman line shapes of simple molecular fluids exhibit critical line broadening near their respective liquid-gas critical points. In order to observe this phenomenon, it is essential that the band position of a given vibrational mode is density-dependent, and that vibrational depopulation processes negligibly contribute to line broadening. Special attention was given to the fact that the isotropic (i.e., nonrotationally broadened) line shape of liquid N2 is affected by resonant intermolecular vibrational interactions between identical oscillators. By means of the well-chosen isotopic mixture (14N2).975 - (14N15N).025, the temperature and density dependences of shift, width, and asymmetry of the resonantly coupled 14N2 and, depending on the S/N ratio available, of the resonantly uncoupled 14N15N were determined, with up to milli-Kelvin resolution, in the coexisting liquid and gas phases and along the critical isochore, using a highest-resolution double monochromator and modern charge-coupled device detection techniques. Clear evidence was found that vibrational resonance couplings are present in all dense phases studied.