Kaun N, Baena J R, Newnham D, Lendl B
Institute of Chemical Technologies and Analytics, Vienna University of Technology, Getreidemarkt 9-164, 1060 Vienna, Austria.
Appl Spectrosc. 2005 Apr;59(4):505-10. doi: 10.1366/0003702053641351.
Absorption spectra of aqueous solution of ''chaotropes'' (structure maker) and ''kosmotropes'' (structure breaker) have been recorded in the mid-infrared (MIR) and terahertz (THz) spectral region. A different impact of the two groups of solutes on the absorption spectrum of water was found in the recorded THz spectra. A concentration-dependent increased absorption across the investigated THz spectral region (0.04-2 THz, 1.3-66 cm(-1), respectively) has been recorded for all studied chaotropic solutions, whereas the opposite has been obtained for kosmotrope containing solutions. In the case of ionic solutes a further increase in absorption towards higher frequencies was measured. The distinction between chaotrope and kosmotrope solutes was, as expected, also possible in the MIR spectral region. Depending on the structure-forming effect of the solute the OH stretch vibration of the water (around 3400 cm(-1)) was slightly shifted. A red shift has been observed for solution of kosmotropes, whereas a blue shift was observed in the case of solutions containing chaotropes. Compared to the MIR spectral region the structure influencing effect of solutes can be more efficiently studied in the THz spectral region, which provides information from interactions between neighboring water molecules.
已在中红外（MIR）和太赫兹（THz）光谱区域记录了“离液剂”（结构形成剂）和“促溶剂”（结构破坏剂）水溶液的吸收光谱。在所记录的太赫兹光谱中发现了这两类溶质对水的吸收光谱的不同影响。对于所有研究的离液剂溶液，在整个研究的太赫兹光谱区域（分别为0.04 - 2太赫兹，1.3 - 66厘米⁻¹）都记录到了浓度依赖性的吸收增加，而对于含促溶剂的溶液则得到了相反的结果。对于离子溶质，测量到吸收向更高频率进一步增加。正如预期的那样，在中红外光谱区域也能够区分离液剂和促溶剂溶质。根据溶质的结构形成效应，水的OH伸缩振动（约3400厘米⁻¹）会略有偏移。对于促溶剂溶液观察到了红移，而对于含离液剂的溶液则观察到了蓝移。与中红外光谱区域相比，在太赫兹光谱区域可以更有效地研究溶质对结构的影响，该区域提供了相邻水分子之间相互作用的信息。
