Effect of cylindrical cavity height on laser-induced breakdown spectroscopy with spatial confinement

Abstract

In this paper, we present a study on the spatial confinement effect of laser-induced plasma with a cylindrical cavity in laser-induced breakdown spectroscopy (LIBS). The emission intensity with the spatial confinement is dependent on the height of the confinement cavity. It is found that, by selecting the appropriate height of cylindrical cavity, the signal enhancement can be significantly increased. At the cylindrical cavity (diameter=2 mm) with a height of 6 mm, the enhancement ratio has the maximum value (approximately 8.3), and the value of the relative standard deviation (RSD) (7.6%) is at a minimum, the repeatability of LIBS signal is best. The results indicate that the height of confinement cavity is very important for LIBS technique to reduce the limit of detection and improve the precision.

Double-enhanced LIBS system with N2 atmosphere and cylindrical cavity confinement for quantitative analysis of Sr element in soil

“…The plasma plume expands rapidly and freely in the opposite direction of the laser when the laser acts on the sample surface to produce plasma. The distance between the front of the plume and the sample surface may reach several millimeters, and the effective length of the plume may reach 2 mm to 3 mm [11]. When the height of the cylindrical confinement cavity is shorter than the front position of the plume, it cannot produce an effective confinement effect on the plasma.…”

“…The cylindrical cavity with a diameter of 2 mm and heights of 2, 4, and 6 mm were used (continuing to increase the cavity height would result in partial obscuration of the plasma, and the collected plasma signal would be reduced instead [11]) in three different sets of sizes and a set of four different sizes with a diameter of 4 mm and a height of 6 mm in total were used for the cylindrical cavity confinement enhancement experiments. The different experimental conditions were divided into different groups according to the diameter and height, as shown in table 1.…”

“…Liu et al [10] combined cavity confinement with conventional LIBS, and the experimental results showed that the intensity and SNR of the characteristic spectral lines were increased to some extent, and the detection limit was improved, which enhanced the detection accuracy of heavy metal Ba elements in soil. Shao et al [11] demonstrated that the selection of a suitable cylindrical cavity height can significantly improve the signal enhancement and the reproducibility of LIBS signals. Compared with a single cavity-constrained enhancement method, using a combination of multiple enhancement methods has a stronger ability to enhance the LIBS signal.…”

Effect of distances between lens and sample surface on laser-induced breakdown spectroscopy with spatial confinement

“…The ambient air pressure around the surface of laser ablated sample increases rapidly, therefore, a shockwave is generated. The reflected shockwave compresses plasma plume causing the increase in plasma temperature and electron density, so that the emission intensity is enhanced [41][42][43][44]. Figure 5 shows the evolution of spectral intensities of Si (I) 390.55 nm with spatial confinement and without spatial confinement.…”

Rapid classification of heavy metal soils from different mining areas by using a GSCV quadratic merit seeking network combined with MF-LIBS

“…It has been shown in the literature that external cavity connement can effectively increase the spectral intensity, improve the signal-to-noise ratio of the spectral lines, and enhance the quantitative analysis performance. 20 However, all the existing studies are limited to the spectral enhancement part, and seldom involve the subsequent qualitative and quantitative study of the spectral data.…”