Imaging Molecular Structures with Femtosecond Laser Pulses: Experimental Apparatus Development and Computational Geometry Reconstruction
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Date
2024-01-15
Authors
TIAN, KAILI
Journal Title
Journal ISSN
Volume Title
Publisher
University of Waterloo
Abstract
A joint facility with the University of Waterloo and the Advanced Laser Light Source has been constructed, in order to explore the behavior of ions and electrons during ultrafast molecular dynamics. The sophisticated apparatus known as the Cold Target Recoil Ion Momentum Spectroscopy (COLTRIMS) has been constructed in Waterloo. A COLTRIMS, or reaction microscope, comprises seven essential components: the Time of Flight (TOF) spectrometer, the delay-line detectors, the signal acquisition system, the vacuum system, the cooling system, the magnetic coils, and the analysis software. Detailed assembly procedures, problem diagnosis tests, operational procedures and initial tests using femtosecond laser pulses, to initiate dynamics, are reported.
To investigate the geometric structure of a molecule immediately preceding the initiation of a Coulomb explosion, by a few-cycle laser pulse, an optimized Coulomb explosion geometry reconstruction framework is developed, and explained in detail and validated using both simulation data and experimental data. The application of the geometry reconstruction optimization method, to experimental data resulting from the ionization of asymmetric molecules N2O and OCS by sub 7fs laser pulses, demonstrates its effectiveness of the framework.
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Keywords
femtosecond laser, geometry reconstruction, reaction microscope