Yong-Ill Lee

Applications of Laser-Induced Breakdown Spectrometry

INTRODUCTION When a high-powered laser beam is focused onto a small area or spot of a solid surface, the temperature of the locally heated region rises rapidly to the vaporization temperature of the solid material and an optically induced plasma, frequently called a laser-induced plasma (LIP) or laser-ablated plasma (LAP) or laser spark is formed at the surface. The plasma will be formed when the laser power density exceeds the breakdown threshold value of the solid surface. Although different materials have different breakdown thresholds, an optical plasma is produced when the laser power density exceeds several megawatts per centimeter squared (106 - 109 W/cm2). This plasma has been used for sampling, atomization, excitation, and ionization in analyhcal atomic spectroscopy. It has also been frequently used and proposed as a source for atomic emission spectrometry (AES). In this case the technique is most ofien referred to as laser microprobe optical emission spectrometry (LM-OES) developed by Brech and ...

Recent Applications of Laser‐Induced Breakdown Spectrometry: A Review of Material Approaches

Abstract The use of laser‐induced breakdown spectrometry (LIBS) has grown steadily, and it has proven to be a relatively dynamic research activity for performing direct spectrochemical elemental or metal analysis of a variety of materials, solids, liquids, and gases, with none or little sample pretreatment procedures. Significant progress has been made during the last several years on the diverse and versatile applications of LIBS including remote material analysis in nuclear power stations, space exploration, diagnostics of archaeological objects, and metal diffusion in solar cells, etc. This review presents the more recent applications of LIBS based on the development of fiber‐optic (FO) technology and portable instrumentation. The characteristics of matrices, object of analysis, laser system used, and analytical performances are tabulated for metallurgical samples, liquid and colloid samples, aerosol and gases, environmental samples, non‐metallic solids, advanced materials, and miscellaneous applications.

Selective optosensing of clenbuterol and melamine using molecularly imprinted polymer-capped CdTe quantum dots.

A novel procedure for the optosensing of clenbuterol and melamine was developed using molecularly imprinted polymer-capped CdTe quantum dots (MIP-CdTe QDs). The MIP-CdTe QDs were synthesized by a radical polymerization process among CdTe QDs, a template, 3-aminopropyltriethoxysilane (APTES) and tetraethoxysilane (TEOS). The sizes of the MIP-CdTe particles were controlled by the speed of polymerization, concentration of the template, concentration of the quantum dots, and the ratio of template, monomer and cross-linker. Excellent selectivity and high sensitivity of MIP-CdTe QDs toward clenbuterol/melamine molecules were observed based on the fluorescence quenching of QDs. Experimental results showed that the optimum molar ratios of template, monomer, and cross-linker were 1:8:20 and 1:4:20 for analyzing clenbuterol and melamine, respectively. Under optimum conditions, these MIP-CdTe QDs showed a limit of detection of 0.4 μM (120 ng/mL) for clenbuterol and 0.6 μM (75 ng/mL) for melamine. The feasibility of the developed method in real samples was successfully evaluated through the analysis of clenbuterol and melamine in milk and liver samples with satisfactory recoveries of 92-97%. The MIP-CdTe QDs could be easily regenerated for subsequent sample analysis with water.

RECENT DEVELOPMENTS IN INSTRUMENTATION FOR LASER INDUCED BREAKDOWN SPECTROSCOPY

ABSTRACT This review describes, in detail, the most recent developments in instrumentation for laser induced breakdown spectroscopy (LIBS). The paper focuses on various laser systems, including excimer, CO2, and Nd: YAG and their performance in LIBS. The coupling of fiber-optics to LIBS and development of portable LIBS systems and their performance is presented. New approaches such as dual pulse operation, multi-fiber, resonant ablation, and combination with laser induced fluorescence are further described. Finally the use of the Echelle spectrometer in which it has been combined with various charge coupled devices.

Interaction of an Excimer-Laser Beam with Metals. Part III: The Effect of a Controlled Atmosphere in Laser-Ablated Plasma Emission:

The effects of pressure over the range 10 to 760 Torr and of atmosphere (air, argon, and helium) on an ArF-excimer laser (λ = 193 nm) ablated plasma created above the surface of a copper target was studied with the use of emission measurements. These factors greatly influenced the shape, line-to-background (L/B) ratio, and temperature of the plasma. In general, the size of the plasma decreased with increasing pressure. In air or argon, and at pressures less than 50 Torr, the plasma consisted of two distinct regions. With the use of neutral copper [Cu(I)] lines, reduced pressure from 760 to 10 Torr resulted in a 7-fold increase in air and an 11-fold increase in an argon atmosphere. With the use of a helium atmosphere, the maximum line intensity was obtained at 50 Torr. This was a 1.5-fold increase over that obtained at 760 Torr. With a reduction in the pressure in air or argon, the position of maximum intensity (for copper atom and ion lines) moved away from the surface. For helium, the position of maximum intensity did not significantly vary in accordance with a reduction in the pressure. In general, the plasma temperature decreased with decreasing pressure.

Novel and recent applications of elemental determination by laser-induced breakdown spectrometry

Following a short introduction to the technique of laser induced breakdown spectrometry for the determination of elements, this min-review will concentrate on the novel and most recent applications which show the advantages of the technique over more conventional atomic spectroscopic techniques. These applications include environmental, metals, liquids, aerosols or gases, non-metallic solids, and advanced materials.

Interaction of a Laser Beam with Metals. Part II: Space-Resolved Studies of Laser-Ablated Plasma Emission

Spatial measurements of the emission spectra of a laser-generated plasma were obtained for copper and lead targets. Results showed that the two metals gave quite different sizes of plasma, the plasma formed with copper extending 2 mm, and that with lead extending 5 mm, above the metal surface. Excitation temperatures of the plasma ranged from 13,200 to 17,200 K for copper and 11,700 to 15,300 K for lead.

Influence of Atmosphere and Irradiation Wavelength on Copper Plasma Emission Induced by Excimer and Q-Switched Nd:YAG Laser Ablation:

Laser-induced copper plasma emission was investigated by time-integrated spatially resolved spectrometry. The comparative work on the plasma emission characteristics—specifically, self-absorption, line broadening, emission intensity, and metal ion formation—was carried out by the use of two different laser systems (XeCl excimer: = 308 nm; Nd:YAG: = 1064 and 532 nm). The characteristics of plasma emission produced by different wavelength radiation on copper atomic and ion lines under various atmospheric gases (argon, neon, and helium) and pressures (760–10 Torr) are presented. The differences in self-absorption and line broadening phenomena in the plasma location were explained by shock wave-driven excitation mechanism for atoms in the outer region in the plasma. The excitation temperatures of the plasma induced by 308- or 532-nm irradiation were also much higher that those induced by 1064-nm irradiation.

Molecularly imprinted solid phase microextraction fiber for trace analysis of catecholamines in urine and serum samples by capillary electrophoresis.

A selective and flexible monolithic moleculary imprinted polymer (MIP) fiber was developed in batch for solid phase microextraction (SPME) of catecholamines (CAs), i.e., dopamine (DA), epinephrine (E) and norepinephrine (NE), and coupled with capillary electrophoresis (CE) for trace analysis of urine and serum samples. The polymer fiber was synthesized in-situ simply using a flexible capillary as a mold and the polymerization protocols and SPME experimental conditions were examined in detail. The reproducibility of fiber to fiber fabrication (n=5) was in range of 5.9-9.8% for three CAs. The fiber also shows high stability without any deterioration of extraction performance after 30 times use. Under the established optimum conditions, the limits of detection for DA, E, and NE were 7.4, 4.8, and 7.1 nmol L(-1), respectively, with the enhancement factor over 100 after MIP-SPME. The specific selectivity to three CAs was discovered with the developed MIP fibers compared with non-imprinted polymer (NIP) fiber. Finally, the MIP fibers were successfully applied for selective extraction of CAs in urine and serum samples with the relative recoveries ranging from 85% to 103%. The fabricated MIP-fibers were promising in preparation of biological samples in batch followed by CE-UV detection.

A chelating resin containing 1-( 2-thiazolylazo) -2-naphthol as the functional group; synthesis and sorption behavior for trace metal ions

A new polystyrene-divinylbenzene resin containing 1-(2-thiazolylazo)-2-naphthol (TAN) functional group was synthesized and its sorption behavior for 19 metal ions including Zr(IV), Hf(IV) and U(VI) was investigated by batch and column experiments. The chelating resin showed a high sorption affinity for Zr(IV) and Hf(IV) at pH 2. Some parameters affecting the sorption of the metal ions are detailed. The breakthrough and overall capacities were measured under optimized conditions. The overall capacities of Zr(IV) and Hf(IV) that were higher than those of the other metal ions were 0.92 and 0.87 mmol/g, respectively. The elution order of metal ions at pH 4 was evaluated as: Zr(IV) > Hf(IV) > Th(IV) > V(V) > Nb(V) > Cu(II) > U(VI) > Ta(V) > Mo(VI) > Cr(III) > Sn(IV) > W(VI). Quantitative recovery of most metal ions except Zr(IV) was achieved using 2 M HNO 3 . Desorption and recovery of Zr(IV) was successfully performed with 2 M HClO 4 and 2 M HCl.