Preliminary analysis of C and H in a “Sangiran” fossil using laser-induced plasma at reduced pressure

Abstract

A Nd:YAG laser (1064nm, 120mJ, and 8ns) was focused on various types of fossil samples, including fossilized buffalo horns (around 400 000 and 1×106yr old, respectively) found in Sangiran, Indonesia. Such fossils represent an important starting point for tracing man’s origin and evolution during the Pleistocene era. Carbon emission was found to decrease significantly with the degree of fossilization and no carbon emission was found in a horn fossil dated at 1×106yr. Some molecular band spectra were also found in all the fossils examined in this study. It was assumed that by combining information on carbon emission, hydrogen emission, and molecular band spectra that the degree of fossilization might be quantitatively calculated. Further results showed that silicon emission is not detected in old fossils, but it is present as a major constituent. This is probably due to the fact that silicon is strongly bound to other elements in old fossils and is ablated in the form of clusters. In order to prove the above hypothesis, a thin film of an old fossil was deposited on a silver plate substrate by means of a laser ablation technique. The resulting film was then irradiated and atomic emission lines of silicon were clearly detected. A comparative study of the low-pressure plasma introduced in this study was conducted using the well-known laser-induced breakdown spectroscopy technique and the results confirmed that operating conditions at atmospheric pressure are unfavorable for a fossil analysis.

Shock wave plasma generation in low pressure ambient gas from powder sample using subtarget supported micro mesh as a sample holder and its potential applications for sensitive analysis of powder samples

“…The resulted plasmas and its related spectra shown in Fig. 2 are found to exhibit a typical hemispherical shape consisting of a small and intense primary plasma and an extended secondary plasma growing out of the primary plasma as observed previously [24][25][26][27][28][29][30][31][32][33][34][35][36][37][38][39]. The relatively tiny primary plasma generally shows very dense white colour originating from the intense continuum emission, while the much larger secondary plasmas extending far beyond the primary plasma reaching a maximum radius of around 25 mm and displays the bright colours of the emission from the associated constituents.…”

Enhancement of carbon detection sensitivity in laser induced breakdown spectroscopy with low pressure ambient helium gas

“…The experimental setup employed in this work is basically similar to those used in our previous works, [21][22] which is schematically presented in Fig. 1 for easy reference.…”

“…These excited He atoms were shown to provide the He assisted excitation (HAE) mechanism for the delayed excitation and emission of the ablated analyte atoms when the plasma becomes relatively cooled and free from the charged particles [13][14][15][16][17][18][19][20][21][22][23][24][25][26]. The benefits of using ambient He gas in LIBS applications have been amply demonstrated in a number of cases according to our previous works, [15][16][17][18][19][20][21][22][23][24][25][26][27][28] including C analysis of steel products [29][30]. Nevertheless its application to C analysis of stones has yet to appear in the literature.…”

Effect of Atmospheric Conditions on LIBS Spectra

“…Additionally, LIBS requires little or no sample preparation and can provide simultaneous multi-element analysis. Thus, it is not surprising that LIBS has been used for a wide variety of applications, such as material analysis [ 1 ], environmental monitoring [ 2 – 4 ], forensics [ 5 ], biological identification [ 4 , 6 ], and even characterization of fossils [ 7 ] and works of art [ 8 ]. There are several excellent reviews [ 9 , 10 ] and books [ 11 – 13 ] on LIBS and its applications.…”