Q-Switched Laser Sampling of Copper—Zinc Alloys

Abstract

A more detailed knowledge than is presently available of laser beam—target material interactions is required if pulsed lasers are to be used with maximum effectiveness as analytical sampling devices. To this end, the Q-switched laser sampling of copper—zinc alloys has been investigated. Both vapor and liquid metal were produced in the sampling process. Observations of the crater dimensions and appearance showed that ablation of molten metal was the predominant material removal mode. It was demonstrated that the melting step was thermally equilibrated. Vaporization proceeded via a sequence of events wherein the vapor composition was independent of laser parameters, and could be predicted from the liquid—solid equilibrium diagram for the copper—zinc system. The effect of laser sampling on a subsequent chemical analysis is illustrated.

Semi-quantitative analysis of metal alloys, brass and soil samples by calibration-free laser-induced breakdown spectroscopy: recent results and considerations

“…Several works have shown that brass samples suffer significantly from fractionation effects and numerous studies have already been carried out to understand the mechanisms behind the fractional ablation using a variety of laser and sample conditions. [44][45][46][47][48][49] The main factors which influence fractionation in brass are the laser wavelength, pulse duration and irradiance. Mao et al 45 indicated that at low irradiances (<0.3 GW cm À2 ) and long pulse durations (>30 ns), the mechanism involved is thermal vaporization, while at higher irradiances (>1 GW cm À2 ) and shorter pulse durations ($3 ns), the mechanism is governed by both thermal and non-thermal processes and the Zn/Cu ratio approaches stoichiometry but the ablated mass always remains enriched in Zn.…”

The Effect of Laser Wavelength on the Selective Vaporization of Cu-Zn Alloy in Laser Ablation at Low Pressure

“…[1][2][3][4][5][6][7] However, selective vaporization of sample atoms often cause serious problem during the laser ablation process, so that the analytical result involves large errors. Selective vaporization was observed by Baldwin 8) and Russo 9) in laser atomization on brass. Recently, selective vaporization in laser-induced plasma at reduced pressures was reported when using TEA CO 2 laser and Q-switched Nd:YAG laser.…”

Selective Vaporization in Q-Switched Nd:YAG Laser Induced Shock Wave Plasma at Low Pressures.

“…It is well known that selective vaporization ordinarily takes place to some extent on target of simple alloy such as brass when it is subjected to laser atomization at 1 atm of surrounding gas. [19][20][21] We have shown, however, that the self-absorption and the selective vaporization negligibly takes place when an UV laser with a short pulse duration is focused on a target at reduced pres- 11,16,22)sures .On the other hand, in another experiment using low irradiance laser, it was demonstrated that selective vaporization takes place seriously. Namely when a TEA CO2 laser was focused onto a brass sample at reduced pressure of around 1 Torr,23) the Cu emission signal could be detected with extremely weak ratio nevertheless the brass sample contains Cu atoms in much higher concentration than Zn atoms.…”