Laser-induced breakdown spectroscopic studies of calcite (CaCO₃) marble using the fundamental (1064 nm) and second (532 nm) harmonic of a Nd:YAG laser

Abstract

Calcium is the fifth most abundant element in the Earth's crust and finds many applications in different fields of science and technology. Laser-induced breakdown spectroscopy (LIBS) was used for the analysis of naturally occurring calcite (CaCO 3 ) marble at atmospheric pressure using the fundamental (1064 nm) and second (532 nm) harmonic of a Q-switched Nd:YAG laser. The emission spectra consist of neutral and singly ionized spectral lines of Ca and Mg, while traces of Al, Sr, and Na were also detected. The Ca lines were observed to dominate the shorter as well as longer wavelength regions and the 4s4d 3 D 2 → 4s4p 3 P 2 transition of Ca (I) at 445.74 nm possessed higher intensity than any other spectral line in the observed spectra. An increase in the signal intensity of the spectral lines was noted with the increase in laser pulse energy. The relative abundance of the pertinent elements was determined by integrated intensities of the strongest lines, and integrated intensities of all lines from each element and the result was 79.74% Ca and 15.49% Mg, revealing them as major constituting elements. The results of the LIBS technique agreed with the outcomes of the same sample studied for microchemical analysis using an electron probe micro analyzer coupled with energy dispersive x-ray spectroscopy. Self-absorption was noted for a doublet of singly ionized Ca (II) line at 397.1 nm. The experimentally observed integrated line intensities of six Ca (I) lines at 364.53, 443.80, 458.86, 526.18, 616.83, and 650.04 nm were used to extract the electron temperature (T e ) using the Boltzmann plot method. The electron number density (N e ) was determined from the Stark broadening profile of a neutral Ca (I) line at 504.37 nm. The values of T e and N e at a 0.05 mm distance from the target surface with a pulse energy of 40 mJ were found to be 8500 K and 3.53 × 10 16 cm −3 for the 1064 nm laser. The same parameters were observed to be 6800 K and 3.87 × 10 16 cm −3 for the 532 nm laser. The relationship between electron temperature and number density was found to be directly related to the laser irradiance, while inverse proportionality was observed for the distance (0.05-2.0 mm) from the target surface.

A Review on Laser-Induced Breakdown Spectroscopy in Different Cancers Diagnosis and Classification

“…For excitation and de-excitation purposes, a high-energy pulsed laser (Nd: YAG laser with typical wavelength 1,064 nm) is applied to the sample (usually within nanosecond range) in LIBS [29], because of its durability, ease of use, and high energy peak pulse. Similarly, Nd: YAG laser second and third harmonic wavelengths 532 and 355 nm are also often used as excitation sources [37,38]. The femtosecond (fs) laser is also used in various applications of LIBS [29].…”

Role of Focusing Distance in Picosecond Laser-Induced Cu Plasma Spectra

“…To enhance the spectral intensity and improve the analytical precision, a larger number of insightful studies have been offered within the past ten years. For example, Fahad and Abrar used a pulse of wavelength 1064 nm and 532 nm to analyze the plasma characteristics of marble calcite [11]. When a femtosecond laser is used to ablate a copper target, the spectral intensity of Cu(I) and Zn(I) is higher when the laser is circularly polarized rather than linearly polarized [12].…”

Applications of laser-induced breakdown spectroscopy in cultural heritage and archaeology: a critical review

“…Other works that used LIBS for monitoring the cleaning processes of marble and stones were published in 2001 by Dickman et al [112] and Klein et al [113], who studied the discoloration of marble following the laser cleaning, by Hildenhagen and Dickmann in 2003 [114], by Colao et al [115] in 2004 and by Khedr et al [116] in 2011. The LIBS analysis of historical marbles for provenience studies was proposed by Lazic et al in 2004 [117] and then performed in 2007 by Bakry on marbles from Jeddah, Saudi-Arabia [118], Mahmood et al [119] in 2010, on a variety of marbles extracted from Quetta region of Boluchistan, Pakistan, and by Fahad and Abrar in 2018 [120]. Columbu et al [121] used LIBS for the analysis of limestone Nuragic statues from Mont'e Prama archaeological site (XI-IX cent.…”