浓度微扰下硝酸水溶液中氢键作用的二维相关拉曼光谱研究  

Investigation of Hydrogen Bonding in Aqueous Nitric Acid Solution Under Concentration Perturbation by Two-Dimensional Correlated Raman Spectroscopy

作　　者：杨博 张雅茹 程碧瑶 李雨蔚 屈鹏飞 唐辉[1] 柳海斌[1] 王小卓 YANG Bo;ZHANG Ya-ru;CHENG Bi-yao;LI Yu-wei;QU Peng-fei;TANG Hui;LIU Hai-bin;WANG Xiao-zhuo(Xi'an Institute of Electromechanical Information Technology,Xi'an 710065,China)

机构地区：[1]西安机电信息技术研究所,陕西西安710065

出　　处：《光谱学与光谱分析》2025年第4期958-963,共6页Spectroscopy and Spectral Analysis

摘　　要：硝酸被称为“国防工业之母”,其水溶液的稀释浓度对火炸药生产至关重要。通过搭建腔增强型拉曼光谱仪,提高拉曼激发和收集效率,实现对硝酸质量分数(ω)为35.49%~88.98%的细微浓度差异的硝酸水溶液进行测量。分析900~1400 cm^(-1)范围内的硝酸拉曼光谱,发现965 cm^(-1)处N—OH伸缩振动模式随着硝酸浓度变化发生显著频移。随着硝酸质量分数增加,当35.49%≤ω≤55.10%时,N—OH伸缩振动模式快速红移,这归因于HNO_(3)—nH_(2)O(n=1,2,…)团簇结构的形成;当ω>55.10%时,N—OH伸缩振动模式红移程度逐渐变小,这可能是因为硝酸与水分子之间形成的氢键逐渐减少的缘故;当ω>68.78%时,N—OH伸缩振动模式红移程度增大,这源于硝酸分子内氢键的增多。此外,深入研究1050 cm^(-1)处N—O全对称伸缩振动模式与1300 cm^(-1)处N—OH反对称伸缩振动模式的谱峰强度随硝酸浓度的变化。随着硝酸质量分数增加,当35.49%≤ω≤55.10%时,1050与1300 cm^(-1)的拉曼峰面积比快速减小;当ω>55.10%时,该拉曼峰面积比减小幅度放缓;当ω>68.78%时,该拉曼峰面积比的变化趋于稳定。1050与1300 cm^(-1)的拉曼峰面积比值的减小可以归因于NO-3(N—O全对称伸缩振动模式)逐渐减少,而未解离HNO_(3)(N—OH反对称伸缩振动模式)逐渐增加。上述光谱峰频移和强度变化表明,在可用样本量范围内,当ω分别达到55.10%和68.78%时,HNO_(3)—nH_(2)O团簇结构均会发生转变。结合密度泛函理论(DFT)进一步阐释谱峰强度和频移变化机理。当35.49%≤ω≤55.10%时,硝酸水溶液中HNO_(3)—3H_(2)O和HNO_(3)—2H_(2)O是主要存在形式。当ω>55.10%时,溶液中HNO_(3)—nH_(2)O逐渐转变为HNO_(3)—H_(2)O团簇。当ω>68.78%时,硝酸水溶液中未解离的HNO_(3)逐渐占据优势。最后,对一维拉曼光谱进行二维相关分析,揭示HNO_(3)/NO-3的谱峰来源。结果证实1308和958 cm^(-1)的谱峰代表未解离的HNO_(3)分Nitric acid is known as the“mother of the national defense industry”,and the dilution concentration of its aqueous solution is crucial for producing explosives.This paper improves the Raman excitation and collection efficiency by constructing a cavity-enhanced Raman spectrometer.It achieves the measurement of aqueous nitric acid solutions with fine concentration differences ranging from 35.49%to 88.98%in nitric acid mass fraction(ω).Analyzing the Raman spectra of nitric acid within the range of 900~1400 cm^(-1),it was found that the N—OH stretching vibration mode at 965 cm^(-1)showed a significant frequency shift with changes in nitric acid concentration.When 35.49%≤ω≤55.10%,an increase in nitric acid concentration induces a rapid red shift in the N—OH stretching vibration mode,attributed to the formation of HNO_(3)—n H_(2)O(n=1,2,…)cluster structures.Whenω>55.10%,the degree of redshift in the N—OH stretching vibration mode gradually decreases,which may be because the hydrogen bonds(H-bonds)formed between nitric acid and water molecules decrease.Whenω>68.78%,the degree of redshift in the N—OH stretching vibration mode expands again due to increased H-bonds within nitric acid molecules.In addition,the intensity of the N—O fully symmetric stretching vibration mode at 1050 cm^(-1)and the N—OH asymmetric stretching vibration mode at 1300 cm^(-1)as a function of nitric acid concentration were also studied.When 35.49%≤ω≤55.10%,the area ratio of Raman peaks at 1050 and 1300 cm^(-1)decreases rapidly as the nitric acid concentration increases.However,the decrease in the area ratio at 1050 and 1300 cm^(-1)slows down atω>55.10%.The area ratio tends to stabilize atω>68.78%,which is attributed to NO-3 gradually decreases and undissociated HNO_(3)increases.The above Raman shift and peak intensity indicate that within the available sample range in this paper,the HNO_(3)—n H_(2)O cluster structure will transform whenωreaches 55.10%and 68.78%,respectively.Further,explain the mechanism of peak

关 键 词：拉曼光谱 硝酸水溶液 氢键作用 二维相关光谱 DFT计算 

分 类 号：O561.3[理学—原子与分子物理]