  Laser induced breakdown spectroscopy (LIBS) has become a proven contemporary
workhorse for qualitative and quantitative analysis of materials. Recent
developments in LIBS have been limited either to signal enhancement strategies
or to advances in data analysis techniques that yield better interpretation of
LIBS data. Explorations of the initial laser excitation stage of LIBS remain
somewhat restricted. In particular, the influence, if any, of the polarization
state of excitation laser remains unexplored to a large extent. The current
work addresses this lacuna in knowledge by probing the influence of different
polarization states of the excitation laser on LIBS spectra of metallic copper.
Specifically, we investigate the behaviour of atomic and ionic emission lines
with respect to change in polarization state of the incident laser light; our
results show distinct polarization dependence. Our observations open up new
opportunities of tackling the problem of relatively faint emissions from ionic
species in the plasma by adjusting the polarization state of the laser. Our
findings also highlight the urgent need for appropriate theoretical study to be
undertaken so that proper insights can be developed into the physics that drive
the observations that we report here.
