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Study of Ga, GaN, Li and LiF laser ablation plumes using spectroscopic and fast imaging techniques

McKiernan, A.P (2003) Study of Ga, GaN, Li and LiF laser ablation plumes using spectroscopic and fast imaging techniques. PhD thesis, Dublin City University.

The thesis describes the design and implementation of (1) a spatially resolved ultraviolet emission spectroscopy system and (2) an ultrafast imaging experimental setup to study the dynamics and composition of laser ablation plumes suitable for Pulsed Laser Deposition (PLD) of materials. These techniques allow the simultaneous recording of the plume absolute emission intensities up to 4 cm above the target surface, in the spectral range from 240 nm to 900 nm with a series of frames of the expanding plume, thus furnishing spatial, temporal an spectral information on the plume's evolution. Emission spectra of Ga and GaN ablation plumes, in typical PLD conditions, were obtained with this system and are presented as a function of N2 ambient gas pressure from 1 x 10~7 to 5 mbar and ablation laser wavelengths of 266, 355, 532 and 1064 nm. Atomic level populations and excitation temperatures are estimated from these spectra. A series of temporally resolved images of the luminous plume expanding into N2 pressures of 1 x 10-5, 1 x 10—2, 1 x 10-1, 1 and 5 mbar were recorded and plume velocities are estimated from these data. Emission spectra are also presented for Li and LiF plumes expanding into vacuum and the corresponding atomic level populations and excitation temperatures were estimated. Ultrafast images were recorded as a function of laser wavelength (266, 532 and 1064nm) and spotsize (115 x 80, 340 x 250, 90 x 525, 1000 x 000 and 2000x2000 ¿¿m) yielding plume velocities. An anomalous emission line ratio feature of these spectra was observed and discussed.
Item Type:Thesis (PhD)
Date of Award:2003
Supervisor(s):Mosnier, Jean-Paul
Uncontrolled Keywords:Pulsed laser deposition; Laser ablation; Lithium fluoride; Gallium nitride
Subjects:Physical Sciences > Physics
DCU Faculties and Centres:DCU Faculties and Schools > Faculty of Science and Health > School of Physical Sciences
Use License:This item is licensed under a Creative Commons Attribution-NonCommercial-No Derivative Works 3.0 License. View License
ID Code:18069
Deposited On:08 May 2013 14:52 by Celine Campbell . Last Modified 23 Aug 2013 08:45

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