Acta Phys. -Chim. Sin. ›› 2010, Vol. 26 ›› Issue (09): 2473-2480.doi: 10.3866/PKU.WHXB20100922

• PHOTOCHEMISTRY AND SPECTROSCOPY • Previous Articles     Next Articles

Effects of Salts on theMicrostructure ofMethanol

YU Xiao-Chun, LIN Ke, HU Nai-Yin, ZHOU Xiao-Guo, LIU Shi-Lin   

  1. Hefei National Laboratory for Physical Sciences at the Microscale, Department of Chemical Physics,University of Science and Technology of China, Hefei 230026, P. R. China
  • Received:2010-05-25 Revised:2010-06-08 Published:2010-09-02
  • Contact: LIU Shi-Lin E-mail:slliu@ustc.edu.cn
  • Supported by:

    The project was supported by the National Natural Science Foundation of China (20873131, 20928002) and National Key Basic Research Programof China (973) (2007CB815204).

Abstract:

We studied the effects of salts on the microstructure of liquid methanol using the Raman spectra. We compared the excess Raman spectra of different methanolic salt solutions in the O—H and C—O stretching regions. These regions reflect the interactions between anions (cations) and methanol molecules. In the O—H stretching region, the excess spectra show that the anions interact with methanol molecules by weak hydrogen bonding and the strength of the hydrogen bonds decrease according to the order: CH3OH-CH3OH>Cl--CH3OH>NO- 3 -CH3OH>ClO- 3 -CH3OH. Additionally, no interactions between cations and methanol molecules are apparent, as determined after analysis of this region. In the C—O stretching region, the excess Raman spectra show the interactions between anions (cations) and methanol molecules. The C—O stretching vibration frequencies of methanol that interact with the anions and cations increase according to the order: CH3—OH (anions)3—OH (bulk)3—OH (cations). According to the excess Raman spectra in the C—O stretching region, we fitted the Raman spectra and used the fitting results to determine the solvation numbers in the first solvation shell of the ions. The Raman spectra show that the ions do not affect the microstructure of liquid methanol beyond the first solvation shell at this concentration (~0.005).

Key words: Raman spectrum, Anion, Cation, Methanol, First solvation shell

MSC2000: 

  • O645