Optical Emission Studies of Copper Plasma Induced Using Infrared Transversely Excited Atmospheric (IR TEA) Carbon Dioxide Laser Pulses

Abstract

Spatially resolved, time-integrated optical emission spectroscopy was applied for investigation of copper plasma produced by a nanosecond infrared (IR) transversely excited atmospheric (TEA) CO2 laser, operating at 10.6 μm. The effect of surrounding air pressure, in the pressure range 0.1 to 1013 mbar, on plasma formation and its characteristics was investigated. A linear dependence of intensity threshold for plasma formation on logarithm of air pressure was found. Lowering of the air pressure reduces the extent of gas breakdown, enabling better laser-target coupling and thus increases ablation. Optimum air pressure for target plasma formation was 0.1 mbar. Under that pressure, the induced plasma consisted of two clearly distinguished and spatially separated regions. The maximum intensity of emission, with sharp and well-resolved spectral lines and negligibly low background emission, was obtained from a plasma zone 8 mm from the target surface. The estimated excitation temperature in this zone was around 7000 K. The favorable signal to background ratio obtained in this plasma region indicates possible analytical application of TEA CO2 laser produced copper plasma. Detection limits of trace elements present in the Cu sample were on the order of 10 ppm (parts per million). Time-resolved measurements of spatially selected plasma zones were used to find a correlation between the observed spatial position and time delay.

Determination of low alloying element concentrations in cast iron by laser induced breakdown spectroscopy based on TEA CO2 laser system

“…The applicability of TEA CO 2 laser based non-gated LIBS for spectrochemical analysis of various types of solid samples have already been investigated. [15][16][17][18][19] The aim of the present study was to demonstrate the adequacy of a non-gated TEA CO 2 LIBS system for quantitative analysis of trace elements in a powder/ /particulate cast iron samples in air at atmospheric pressure. All cast iron samples (certified standards and unknown samples) were obtained by participation in the 2 nd LIBS Inter-Laboratory comparison test "Powder/Particulate Cast Iron" in July-September 2016.…”

“…LIBS experimental setup used in this study was described in detail in prior publications, 15,17 and will be briefly summarized here.…”

“…The plasma is initiated during the initial peak while the remaining energy of the pulse is absorbed by the plasma plume causing additional heating and excitation. 15,17 All measurements were performed in air at atmospheric pressure. The targets were mounted on a rotating sample holder.…”

LIBS Analysis of Geomaterials: Comparative Study of Basalt Plasma Induced by TEA CO2 and Nd:YAG Laser in Air at Atmospheric Pressure

“…The optical emission from the plasma was viewed in the direction parallel to the target surface (Figure 1(a)). A timeintegrated space-resolved laser-induced plasma spectroscopy (TISR-LIPS) was applied [12,[20][21][22][23]. Spatial resolution was achieved by changing the position of the plasma along the direction of the incoming laser beam.…”

“…In this work, a recently developed LIBS system, based on transversely excited atmospheric (TEA) CO 2 laser and timeintegrated signal detection [12], was applied to the qualitative analysis of basalt samples in air at atmospheric pressure. The basaltic rock was chosen as a representative of geological samples.…”