Raman spectroscopic study of the effects of dissolved NaCl and temperature on water structure

• Main Author: Wang, Yanan.
• Other Authors: Sun Changqing
• Format: Final Year Project
• Language: English
• Published: 2013
• Subjects: DRNTU::Engineering::Electrical and electronic engineering::Microelectronics
• Online Access: http://hdl.handle.net/10356/54393
• Institution: Nanyang Technological University

Water ice exhibited anomalies when under cooling, compressing and clustering excitation. The key to investigate the anomalies as well as cooperative and asymmetric relaxation dynamic in stiffness and length of the H-bond is intramolecular exchange, intermolecular wan der Waals force and ultra-short-range interactions of inter-electron-pair coulomb repulsion. Raman Spectroscopy is to analyze the scattering spectra with different incident light frequency to obtain the molecular vibration and rotation information. It is a kind of analysis method and is utilized to the study of molecular structure. Here Fourier Transform Infrared Raman Spectroscopy was used to explore how the dissolved NaCl as well as how temperature affect water structure. For NaCl solutions with different percentage of solute, there is a clear blue shift of peak around wave number 3300 cm-1 while a red shift occurs near wave number 580 cm-1. It is believed that the addition of NaCl introduces new ions, which breaks the water molecules tetrahedral hydrogen bonding and meanwhile helps to form the donor hydrogen bonding, thus the number of free OH bonds is slightly lowered. When in liquid state, there exist various local hydrogen-bond networks through which the water molecule interacts with its neighboring ones. Although the peak values of FT-IR Spectroscopies of water under different temperatures shows the consistent movement trend with NaCl solutions, the theory behind is quite different. Since non-bond masters in the liquid phase, during the cooling procession, the non-bond significantly contracts and it forces the slave real-bond slightly lengthen, resulting in O-O contraction as well. Further exploitation of the water anomalies like why water has such high heat capacity and why solid phase water (ice) has a smaller density will also be introduced.