Frequency And Vibrational Spectra For Monitoring And Structural Analysis Of Interface Reaction Processes

Sum frequency generation vibrational spectroscopy(SFG-VS) has been applied as a powerful technique to characterize the air/water interface.In this dissertation,a polarization resolved SFG-VS system has been developed to achieve the simultaneous detection of SFG signals at different polarizations.Using such SFG-VS system,the conformation of phosphatidylethanolamine monolayers at different surface pressure and different salt concentrations were investigated.By analyzing the SFG spectra within different wavenumber ranges,the orientation changes of methyl groups at the tail,the methylene,amino groups at the head of PE molecules are also elucidated.The contents of the dissertation are as follows:Chapter 1,summarization of the importance of the interface research,and the review of sum frequency generation applied to the gas-liquid interface as well as Langmuir monolayer interface.Chapter 2,introduction of the non-linear optical effects and the SFG process.The sum frequency generation polarization analysis method and orientation analysis method for accurate measurement.Chapter 3,introduction of the polarization-resolved SFG-VS system and the simultaneous detection of SFG signal at different polarzations.Such SFG-VS system can apply synchronized detection at different polarization,which can also achieve accurate measurements of interface reaction process.Chapter 4,investigation of properties PE monoalyers using the sum frequency generation vibrational spectroscopy,combined with the pressure of membrane isothermal curves,brewster Angle microscopy.Conformation analysis of phosphate groups and methyl groups of PE molecules,as well as the changes of the orientation Angles.Chapter 5,Investigation of properties of deuterated PE monolayers at different salt concentrations using the sum frequency generation vibrational spectroscopy.Conformation analysis of the alkyl chains in the tail and the methylene,amino group in the head of PE molecules. Chapter 6,review of this dissertation and the perspective of SFG-VS investigations.