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Development of laser spectroscopy for elemental and molecular analysis

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Date Issued:
2013
Abstract/Description:
Laser-Induced Breakdown Spectroscopy (LIBS) and Raman spectroscopy are still growing analytical and sensing spectroscopic techniques. They significantly reduce the time and labor cost in analysis with simplified instrumentation, and lead to minimal or no sample damage. In this dissertation, fundamental studies to improve LIBS analytical performance were performed and its fusion with Raman into one single sensor was explored.On the fundamental side, Thomson scattering was reported for the first time to simultaneously measure the electron density and temperature of laser plasmas from a solid aluminum target at atmospheric pressure. Comparison between electron and excitation temperatures brought insights into the verification of local thermodynamic equilibrium condition in laser plasmas.To enhance LIBS emission, Microwave-Assisted LIBS (MA-LIBS) was developed and characterized. In MA-LIBS, a microwave field extends the emission lifetime of the plasma and stronger time integrated signal is obtained. Experimental results showed sensitivity improvement (more than 20-fold) and extension of the analytical range (down to a few tens of ppm) for the detection of copper traces in soil samples. Finally, laser spectroscopy systems that can perform both LIBS and Raman analysis were developed. Such systems provide two types of complimentary information (-) elemental composition from LIBS and structural information from Raman. Two novel approaches were reported for the first time for LIBS-Raman sensor fusion: (i) an Ultra-Violet system which combines Resonant Raman signal enhancement and high ablation efficiency from UV radiation, and (ii) a Ti:Sapphire laser based NIR system which reduces the fluorescence interference in Raman and takes advantage of femtosecond ablation for LIBS.
Title: Development of laser spectroscopy for elemental and molecular analysis.
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Name(s): Liu, Yuan, Author
Richardson, Martin, Committee Chair
Vanstryland, Eric, Committee Member
Bass, Michael, Committee Member
Sigman, Michael, Committee Member
University of Central Florida, Degree Grantor
Type of Resource: text
Date Issued: 2013
Publisher: University of Central Florida
Language(s): English
Abstract/Description: Laser-Induced Breakdown Spectroscopy (LIBS) and Raman spectroscopy are still growing analytical and sensing spectroscopic techniques. They significantly reduce the time and labor cost in analysis with simplified instrumentation, and lead to minimal or no sample damage. In this dissertation, fundamental studies to improve LIBS analytical performance were performed and its fusion with Raman into one single sensor was explored.On the fundamental side, Thomson scattering was reported for the first time to simultaneously measure the electron density and temperature of laser plasmas from a solid aluminum target at atmospheric pressure. Comparison between electron and excitation temperatures brought insights into the verification of local thermodynamic equilibrium condition in laser plasmas.To enhance LIBS emission, Microwave-Assisted LIBS (MA-LIBS) was developed and characterized. In MA-LIBS, a microwave field extends the emission lifetime of the plasma and stronger time integrated signal is obtained. Experimental results showed sensitivity improvement (more than 20-fold) and extension of the analytical range (down to a few tens of ppm) for the detection of copper traces in soil samples. Finally, laser spectroscopy systems that can perform both LIBS and Raman analysis were developed. Such systems provide two types of complimentary information (-) elemental composition from LIBS and structural information from Raman. Two novel approaches were reported for the first time for LIBS-Raman sensor fusion: (i) an Ultra-Violet system which combines Resonant Raman signal enhancement and high ablation efficiency from UV radiation, and (ii) a Ti:Sapphire laser based NIR system which reduces the fluorescence interference in Raman and takes advantage of femtosecond ablation for LIBS.
Identifier: CFE0005105 (IID), ucf:50729 (fedora)
Note(s): 2013-05-01
Ph.D.
Optics and Photonics, Optics and Photonics
Doctoral
This record was generated from author submitted information.
Subject(s): Laser-Induced Breakdown Spectroscopy -- Laser Plasma -- Thomson Scattering -- Raman Spectroscopy
Persistent Link to This Record: http://purl.flvc.org/ucf/fd/CFE0005105
Restrictions on Access: public 2013-11-15
Host Institution: UCF

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