TITLE:
Self-Absorption Effects on Electron Temperature-Measurements Utilizing Laser Induced Breakdown Spectroscopy (LIBS)-Techniques
AUTHORS:
Shawqi A. M. Mansour
KEYWORDS:
Laser Induces Breakdown Spectroscopy (LIBS), Self-Absorption (SA), Saha-Boltzmann Plot, Delay Time (Td), Electron Number Density (Ne), Plasma Temperature (Te)
JOURNAL NAME:
Optics and Photonics Journal,
Vol.5 No.3,
March
20,
2015
ABSTRACT: In the
present work, we have studied the temporal evolution of aluminum alloy plasma
produced by the fundamental (1064 nm) of a Q-switched Nd:YAG laser by placing
the target material in air at atmospheric pressure. The four Al I-neutral lines
at 308.21, 309.27, 394.40 and 369.15 nm as well as Al II-ionic lines at 281.61,
385.64 and 466.30 nm are used for the determination of the electron temperature Te using Saha-Boltzmann plot method. The neutral aluminum
lines were found to suffer from optical thickness which manifested itself on
the form of scattered points around the Saha-Boltzmann line. The isolated
optically thin hydrogen Hα-line
at 656.27 nm appeared in the spectra under the same experimental conditions was
used to correct the Al I-lines which contained some optical thickness. The
measurements were repeated at different delay times ranging from 1 to 5 μs. The
comparison between the deduced electron temperatures from aluminum neutral
lines before correction against the effect self-absorption to that after
correction revealed a precise value in temperature. The results sure that, in
case of the presence of self-absorption effect the temperature varies from
(1.4067 - 1.2548 eV) as the delay time is varied from 0 to 5 μs. Whereas, in
the case of repairing against the effect, it varies from (1.2826 - 0.8961 eV)
for the same delay time variation.