Raman spectra from very concentrated aqueous NaOH and from wet and dry, solid, and anhydrous molten, LiOH, NaOH, and KOH.
Raman spectra from very concentrated aqueous NaOH and from wet and dry, solid, and anhydrous molten, LiOH, NaOH, and KOH.
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来自非常浓的 NaOH 水溶液以及来自湿的和干的、固体的和无水熔融的 LiOH、NaOH 和 KOH 的拉曼光谱。
DOI：
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发表时间：
2006
影响因子：
4.4
通讯作者：
R. Douglas
中科院分区：
文献类型：
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作者：
G. Walrafen;R. Douglas
在480 K下，获得了从NaOH水溶液到2NaOHH 2 O（X（NaOH）=0.667）的高温高压拉曼光谱。当X（NaOH）≥ 0.5时，H_3O_2 ~-占主导地位。由Franck和Charuel的数据计算得到的NaOH水溶液在473 K和1 kbar下的IR xi函数色散曲线表明，OH-离子通过优先与非氢键OH基团形成H_3 O_2-。从湿的到无水的固体LiOH、NaOH和KOH的拉曼光谱分别在3664、3633和3596 cm（-1）处产生尖锐的对称OH伸缩峰，加上与水相关的，即，H3 O2-，在LiOH，3562 cm（-1），NaOH，3596 cm（-1）和KOH，3500 cm（-1）附近的峰。固体中不存在H3 O2-峰确保了相应的熔体是无水的。来自无水熔体的拉曼光谱产生OH-伸缩峰频率：LiOH，3614+/-4 cm（-1），873 K; NaOH，3610+/-2 cm（-1），975 K;和KOH，3607+/-2 cm（-1），773 K，但是存在由于离子对相互作用引起的低频不对称性，其中心在3550 cm（-1）附近。与离子对相关的不对称性对应于在623 K下无水熔融NaOH在3550 cm（-1）附近的唯一IR最大值。玻色-爱因斯坦修正发表的低频拉曼数据从熔融LiOH揭示了声学声子，近205厘米（-1），有关限制平移的OH-与Li+，和光学声子，在625厘米（-1）和τ约0.05 ps，由于质子旋进和/或摆动运动。水与OH-的O原子之间的强氢键形成H3 O2-，但OH-的质子不与H显著成键。大的拉曼带宽（水溶液）解释的不均匀加宽，由于质子转移在双井。振动分配H3 O2-。
High-temperature, high-pressure Raman spectra were obtained from aqueous NaOH solutions up to 2NaOHH2O, with X(NaOH)=0.667 at 480 K. The spectra corresponding to the highest compositions, X(NaOH)> or =0.5, are dominated by H3O2-. An IR xi-function dispersion curve for aqueous NaOH, at 473 K and 1 kbar, calculated from the data of Franck and Charuel indicates that the OH- ion forms H3O2- by preferential H bonding with nonhydrogen-bonded OH groups. Raman spectra from wet to anhydrous, solid LiOH, NaOH, and KOH yield sharp, symmetric OH- stretching peaks at 3664, 3633, and 3596 cm(-1), respectively, plus water-related, i.e., H3O2-, peaks near LiOH, 3562 cm(-1), NaOH, 3596 cm(-1), and, KOH, 3500 cm(-1). Absence of H3O2- peaks from the solid assures that the corresponding melt is anhydrous. Raman spectra from the anhydrous melts yield OH- stretching peak frequencies: LiOH, 3614+/-4 cm(-1), 873 K; NaOH, 3610+/-2 cm(-1), 975 K; and, KOH, 3607+/-2 cm(-1), 773 K, but low-frequency asymmetry due to ion-pair interactions is present which is centered near 3550 cm(-1). The ion-pair-related asymmetry corresponds to the sole IR maximum near 3550 cm(-1) from anhydrous molten NaOH, at 623 K. Bose-Einstein correction of published low-frequency Raman data from molten LiOH revealed an acoustic phonon, near 205 cm(-1), related to restricted translation of OH- versus Li+, and an optical phonon, at 625 cm(-1) and tau approximately 0.05 ps, due to protonic precession and/or pendular motion. Strong H bonding between water and the O atom of OH- forms H3O2-, but the proton of OH- does not bond with H significantly. Large Raman bandwidths (aqueous solutions) are explained in terms of inhomogeneous broadening due to proton transfer in a double well. Vibrational assignments are presented for H3O2-.