【摘要】 应用拉脱法和激光衍射法测定了蒸馏水、自来水和水库水的表面张力,并用激光拉曼光谱仪测定了它们的室温拉曼光谱。结果表明,水表面张力随温度升高而减小,相同温度下表面张力随水中杂质物含量增加而增大。水样品表面张力的差别源于水中所含杂质离子的种类和杂质离子的浓度以及不同荷电杂质离子与水分子的相互作用,弱化或破坏了水分子的氢键作用。拉脱法结果更接近于理论值,激光衍射法结果与理论值偏差相对较大。水拉曼散射说明水拉曼峰的相对强度、半高宽、拉曼频移、峰形对称性等都受水中溶解的杂质离子影响。水中富含的荷电离子产生的局域电场以及与水分子偶极作用产生的统计涨落导致的局域模效应引起的氢键变化影响水分子的振动,从而改变着水团簇结构,使水分子极化率降低,表现为拉曼散射的差异。更多还原

【Abstract】 The surface tension of distilled water,tap water,and reservoir’s water was measured by pulloff method and laser diffraction method.The Raman spectra of these water specimens were recorded by laser Raman spectrometer at room temperature.The results reveal that the surface tension of water increases with the rising temperature and/or impurity concentration.The rank of surface tension in descending order is:reservoir’s water,tap water,and distilled water.The varying of surface tension comes from the impurities’diversity,the concentration variation,as well as the impurity-water molecule interaction.This interaction weakens and/or breaks the hydrogen bond among water molecules,which appears as the increase of surface tension.The pull-off method is a static approach,so its results can resist the influence from vapor phase and are close to theoretical values.While the laser diffraction method is a dynamic approach,so its results are affected by the vapor phase,and therefore exist certain deviations from the theoretical values.In the Raman spectra of water samples,the relative intensity,FWHM,and symmetry of peaks show a dependence on impurity concentration.The Raman spectra of sodium chloride solution with different concentrations illustrate that the relative peak intensity and FWHM decrease with the increase of concentration.While the Raman shift has an increasing tendency with the rising concentration.These facts indicate that the dissolved impurities influence its Raman scattering mechanism.In detail,for the relative peak intensity and FWHM,the descending sequence of water specimens is as follows:distilled water,tap water,and reservoir’s water.And the rank of Raman shift in ascending order is:distilled water,tap water,and reservoir’s water.The peaks of the three specimens are similar in shape,but differ in relative intensity,FWHM,Raman shift,and symmetry.Furthermore,these differences origin from the diversity of impurity,as well as their concentrations.Since the impurity ions carry certain amount of charges,their local electrical filed and the statistical-fluctuation-induced local mode effect,caused by the interaction between the water dipole and the charged impurity,lead to the changing of hydrogen bond and the vibration of water molecules.These factors impact the structure of water molecule clusters,lower its polarizability,which represent as the varying in the Raman scattering.更多还原