INDUCED PLASMA SPECTROSCOPY; ATOMIC EMISSION-SPECTROMETRY; VACUUM-ULTRAVIOLET; SULFUR; STEEL; NANOPARTICLES; CALIBRATION; SAMPLES; RATIOS; SYSTEM

This work introduces a new approach to perform LIBS elemental imaging in the vacuum ultraviolet (VUV) wavelength range by using an argon purged probe coupled to a compact spectrometer. In spite of several important elements for geological and industrial applications such as S, P, As, B, C, or Zn presenting strong lines in the VUV range, the need for using specific optics and working under oxygen-free conditions has limited the extension of LIBS systems available for such a range. Herein, we present an adaptation of our LIBS imaging instrumentation to access the VUV while operating under ambient conditions. The proposed detection system is based on an optical probe directly coupled to a Maya2000Pro compact spectrometer (Ocean Optics), all purged with argon. The technical design along with a detailed evaluation of the VUV probe is addressed. The possibility of using this VUV probe for LIBS imaging is also investigated by studying a Canadian mine core sample with special emphasis on the detection of sulfur. In addition to sulfur, more than 15 elements including P, As, C, Ca, Si, Mo, B, and Zn have also been detected. Elemental images covering sample surfaces in the range of cm(2) with a micrometric spatial resolution (10 mu m) are presented. A detection limit of 0.2 wt% for sulfur is demonstrated in a single shot configuration. These results open new perspectives for both conventional LIBS and LIBS-based imaging in various application fields.

STALAGMITE LAMINAE; TRACE-ELEMENTS; SR-ISOTOPE; SPELEOTHEMS; GROWTH; RATIOS; SPECTROMETRY; SYSTEMATICS; SKELETON; SIGNALS

Paleoclimate studies play a crucial role in understanding past and future climates and their environmental impacts. Current methodologies for performing highly sensitive elemental analysis at micrometre spatial resolutions are restricted to the use of complex and/or not easily applied techniques, such as synchrotron radiation X-ray fluorescence micro- analysis (mu-SRXRF), nano secondary ion mass spectrometry (nano-SIMS) or laser ablation inductively coupled plasma mass spectrometry (LAICP-MS). Moreover, the analysis of large samples (> few cm 2) with any of these methods remains very challenging due to their relatively low acquisition speed(similar to 1-10Hz), and because they must be operated in vacuum or controlled atmosphere. In this work, we proposed an imaging methodology based on laser-induced breakdown spectroscopy, to perform fast multi-elemental scanning of large geological samples with high performance in terms of sensitivity (ppm-level), lateral resolution (up to 10 mu m) and operating speed (100 Hz). This method was successfully applied to obtain the first megapixel images of large geological samples and yielded new information, not accessible using other techniques. These results open a new perspective into the use of laser spectroscopy in a variety of geochemical applications.

LIBS imaging; Elemental imaging; Human paraffin-embedded tissue; Skin cancer;PLASMA-MASS SPECTROMETRY; SQUAMOUS-CELL CARCINOMA; X-RAY MICROSCOPY; LA-ICP-MS; BIOLOGICAL TISSUE; NANOPARTICLES; SKIN; RESOLUTION; ELEMENTS; METALS

Chemical elements play central roles for physiological homeostasis in human cells, and their dysregulation might lead to a certain number of pathologies. Novel imaging techniques that improve the work of pathologists for tissue analysis and diagnostics are continuously sought. We report the use of Laser-Induced Breakdown Spectroscopy (LIBS) to perform multi-elemental images of human paraffin-embedded skin samples on the entire biopsy scale in a complementary and compatible way with microscope histopathological examination. A specific instrumental configuration is proposed in order to detect most of the elements of medical interest (i.e. P, Al, Mg, Na, Zn, Si, Fe, and Cu). As an example of medical application, we selected and analysed skin biopsies, including healthy skin tissue, cutaneous metastasis of melanoma, Merkel-cell carcinoma and squamous cell carcinoma. Clear distinctions in the distribution of chemical elements are observed from the different samples investigated. This study demonstrates the high complementarity of LIBS elemental imaging with conventional histopathology, opening new opportunities for any medical application involving metals. (C) 2017 Elsevier B.V. All rights reserved.

BISMUTH TANTALATE CERAMICS; QUANTITATIVE-ANALYSIS; TRANSPARENT CERAMICS; OPTICAL-PROPERTIES; THIN-FILMS; MICROSTRUCTURE; FABRICATION; ABSORPTION

Strict control of composition is of paramount importance for the reproducible fabrication of advanced ceramics. In particular, the preparation of high-grade transparent ceramics of definite line-compounds requires that the ratio of major constitutive elements be quantified with a precision better than a fraction of a mole percent to prevent the precipitation of secondary phases and the scattering of light. Such a requirement poses difficult challenges to most analytical methods, especially when applied to nearly-stoichiometric insulating phases. In this work, we show that laser-induced breakdown spectroscopy (LIBS) is a well-suited technique for the assessment of non-stoichiometry in yttrium aluminum garnet (YAG) ceramics and that the aluminum to yttrium ratio can be determined with a resolution of 0.3 mol %, well within the phase boundaries of YAG. (C) 2017 Optical Society of America

LIBS; Laser-induced breakdown spectroscopy; Speleothems; Alterations; Ornated cave; Conservation;NEEDLE-FIBER CALCITE; MOONMILK DEPOSITS; TRACE-ELEMENTS; SPELEOTHEMS; ORIGIN; SPECTROMETRY; MORPHOLOGY; RESOLUTION; PROFILES; LIBS

Cave walls are affected by different kinds of alterations involving preservative issues in the case of ornate caves, in particular regarding the rock art covering the walls. In this context, coralloids correspond to a facies with popcorn-like aspect belonging to the speleothem family, mostly composed of calcium carbonate. The elemental characterization indicates the presence of elements that might be linked to the diagenesis and the expansion of the alterations as demonstrated by prior analyses on stalagmites. In this study, we report the use of laserinduced breakdown spectroscopy (LIBS) to characterize the elemental composition of one coralloid sample with a portable instrument allowing punctual measurements and a laboratory mapping setup delivering elemental images with spatial resolution at the micrometric scale, being particularly attentive to Mg, Sr, and Si identified as elements of interest. The complementarity of both instruments allows the determination of the internal structure of the coralloid. Although a validation based on a reference technique is necessary, LIBS data reveal that the external layer of the coralloid is composed of laminations correlated to variations of the LIBS signal of Si. In addition, an interstitial layer showing high LIBS signals for Fe, Al, and Si is interpreted to be a detrital clay interface between the external and the internal part of the coralloid. These preliminary results sustain a possible formation scenario of the coralloid by migration of the elements from the bedrock.