Raman Microprobe Analysis Research Articles

Fluid inclusion and sulphur isotope evidence for syntectonic mineralisation at the Elura mine, southeastern Australia

Fluid inclusion and sulphur isotope data for the discordant, metasediment-hosted massive sulphide deposit at Elura are consistent with a syntectonic origin of the orebodies. Thermometric and laser Raman microprobe analyses indicate that two-phase, primary fluid inclusions are low salinity and H2O-CO2-CH4 types. Inclusion fluids from quartz in ore yield homogenisation temperatures (Th) ranging from 298 ° to 354 °C (mean 320 °C). They are likely to have been trapped close to the solvus of the H2O-CO2-(CH4-NaCl) system and thus should give temperatures of the mineralising fluid. An additional, low Th population of later fluid inclusions is recognised in quartz from ore and syntectonic extension veins in the adjacent wallrock. Th's for these low CO2bearing inclusions range from 150 to 231 °C (mean 190 °C), and should be considerably lower than true trapping temperatures. Sulphur isotopic composition (δ34S) of pyrite, sphalerite, pyrrhotite and galena ranges from 4.7 to 12.6% and indicates a sulphur source from underlying Cobar Supergroup metasediments. An average temperature of 275 °C from the sphalerite-galena sulphur isotopic thermometer suggests isotopic re-equilibration below peak metamorphic temperatures.

Chemical Preparation and Shock Wave Compression of Carbon Nitride Precursors

Two synthetic routes have been developed to produce high‐molecular‐weight organic precursors containing a high weight fraction of nitrogen. One of the precursors is a pyrolysis residue of melamine‐formaldehyde resin. The second precursor is the byproduct of an unusual low‐temperature combustion reaction of tetrazole and its sodium salt. These precursors have been shock compressed under typical conditions for diamond and wurtzite boron nitride synthesis in an attempt to recover a new ultrahard carbon nitride. The recovered material has been analyzed by X‐ray diffraction, FTIR, and Raman microprobe analysis. Diamond is present in the recovered material. This diamond is extraordinarily well ordered relative to diamond shock synthesized from carbonaceous starting materials.

Fluid inclusion studies of the Felbertal scheelite deposit

Fluid inclusion measurements on quartz, scheelite, beryl, fluorite and calcite in the metamorphosed Felbertal scheelite deposit display two main types of fluid inclusions: 1. H2O-CO2 fluid inclusions are characterized by variable amounts of CO2 up to 18 wt.%. They show two or three phases at room temperature. The bulk homogenization temperatures for the inclusions range between +269 °C and +357 °C. The calculated salinities are between 2.2 and 7.8 wt.% NaCl equivalent. For the late CO2-bearing fluid inclusions a methane component is evident from microthermometrical data (Tmclath >10.0 °C combined with TmCO2<−56.6 °C) and from Raman microprobe analyses. 2. Aqueous, two-phase fluid inclusions with salinities in the range between 0 and 11 wt.% NaCl equivalent. Their homogenization temperatures are scattered between 100 °C and 360 °C.

Raman microprobe analysis of GaAs wafers

The Raman microprobe is used for studying the crystalline features of the chemically etched semi-insulating LEC (liquid encapsulated Czochralski) GaAs wafers with a spatial resolution approaching 1 μm. This study reveals the existence of residual compressive stress, which is associated with the existence of excess interstitial arsenic at the walls and in the central regions of the cells. The observation of the arsenic Raman bands (257 and 200 cm -1) after laser heating at 200–250°C seems to confirm the arsenic distribution deduced from the residual stress.

Real Time Optical Diagnostics in Laser Etching and Deposition

AbstractOptical probing of laser-assisted chemical reactions on surfaces in real time can help explain and control these processes. Raman microprobe spectroscopy and micro laser induced fluorescence are the two optical probes employed here to investigate several examples of localized laser surface reactions. Raman microprobe analysis is used to monitor in real time the CuCl and CuCl2 products on the surface during local laser etching of copper films by Cl2 and the concomitant loss of the Cu2O passivation layer. It is also used to follow the production of Cu2O during the laser oxidation of Cu. Polarization Raman analysis is utilized to identify and analyze partially molten silicon during laser heating in vacuum and during the etching of silicon by chlorine. Laser induced fluorescence is used as a real time microprobe of desorbed products during local laser-assisted etching of Si and Al surfaces.

The formation of periodic structure during solid state reactions between SiC and pt

Solid state reactions between the SiC and Pt produce C and Pt-silicides as reaction products. The formation of Pt-silicides gives rise to localized interfacial metling between the Pt and the SiC at temperatures as low as 900°C. In the reaction zones, the C clusters precipitate out in the Pt-silicide matrix either randomly or periodically, depending upon their location from the reaction interface. Laser Raman microprobe analyses identified that the C precipitates exist in two different crystalline states: glassy carbon located close to the SiC reaction interface, and highly ordered carbon farther away

Double-resonance-enhanced Raman scattering in laser-recrystallized amorphous silicon film.

Amorphous silicon films after picosecond laser excitation have been investigated by Raman microprobe analysis. The recrystallized Raman peak intensity can be more than four times that of crystalline Si. By carefully examining the annealed microstructure, the enhancement is interpreted as a double-resonance effect due to microcrystals.

Raman microprobe analysis of temperature profiles in CW laser heated silicon microstructures

Steady-state laser heating of silicon disk microstructure on focused silica and sapphire is examined using the 4880 and 5145 AA lines from an argon-ion laser to heat the disk at the center and to probe it with submicrometer spatial resolution. The Stokes shift and line broadening of the Raman microprobe spectra are compared to simulations of the Raman spectra, which utilize temperature profiles calculated by a finite-difference analysis of the heat flow equation. The Raman simulation model incorporates the effects of temperature inhomogeneities, strain, and photon-created free carriers within the probed volume; temperature nonuniformity is found to be the most important factor and to be quite significant. >

Raman microprobe analysis of strain induced by patterned dielectric films of GaAlAs structures

Raman spectra from GaAlAs layers with Si <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> N <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</sub> stripes obtained with a microprobe are discussed. The spatial resolution of these Raman spectra was smaller than the scale of the microfabricated features. A significant stress-induced shift in the GaAlAs longitudinal optic (LO) phonon frequency has been observed under 3.5 μm wide Si <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> N <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</sub> stripes. Rapid thermal annealing reduced the LO phonon frequency shift, and thus the stress, under the Si <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> N <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</sub> stripe. A corresponding dramatic change in optical waveguide behavior under the stripe was observed.

Application of fluid-inclusion studies to exploration in gold-bearing shear zones: the Cros-Gallet deposit (France) and the Sanoukou prospect (Mali)

A fluid-inclusion study was undertaken on samples from the Cros-Gallet deposit (Haute-Vienne, Massif Central, France) and the Sanoukou prospect (Kenieba district, Mali), both located in large shear zones several kilometres long. Ore mineral paragenesis for both deposits is similar: early arsenopyrite, pyrite and native Au, and later Pb-Ag-Cu sulfosalts, electrum and galena. Quartz samples were used for fluid-inclusion studies. Nondestructive microthermometry and Raman microprobe analysis were used to characterize the ore-forming fluids. Thermobarometric evolution was similar in both deposits and occurred in two stages: 1. (1) Fluid inclusions from the H 2 O-NaCl-CO 2 (CH 4 , N 2 ) system correspond to a drop of pressure in a lithostatic regime and accompanied early Au, As ore deposition. 2. (2) Fluid inclusions from the H 2 O-NaCl system correspond to a drop in temperature and an opening in a hydrostatic regime. It is associated with late Au, As, Pb, Sb ore deposition. This model was used to estimate the Au potential of quartz samples analyzed by standard global destructive analysis (ICP, Gas Chromatography). At Sanoukou, this method allowed assessment, in a given sample, of the relative importance of the two established stages and demonstrated that Au-rich quartz (Au content higher than 1 ppm) was probably genetically related to the aqueous stage. Utilization of this result could be considered in prospecting.

A Raman microprobe study of a magnesia partially stabilized zirconia fracture surface

Raman microprobe analysis has been used to determine the extent of phase transformation on the fracture surface of a magnesia partially stabilized zirconia test bar. This has been found to vary across the fracture face and is considered to be related to the amount of microcracking which occurs in the sample during fracture.

Two-beam laser recrystallization of polycrystalline silicon on an insulating substrate

A novel two-laser technique has been investigated for recrystallizing polycrystalline silicon deposited on an insulating substrate. An Ar+ laser and a CO2 laser have been scanned simultaneously to perform the recrystallization of unpatterned samples and samples patterned with antireflection stripes. The use of the two beams enabled recrystallization without the use of a substrate heater, and resulted in grain widths a factor of 2 larger than those obtained with the more conventional technique using an Ar+ laser only. A Raman microprobe analysis revealed that the stress in the two-beam recrystallized material was about an order of magnitude less than found in Ar+ laser recrystallized material. The polarization dependence of the Raman scattered light indicated that the orientation of the recrystallized material between antireflection stripes was in a 〈100〉 orientation.

Raman microprobe analysis on gaseous inclusions from the diagenetically altered Terres Noires (S-E, France)

Raman microprobe determinations have been made on primary gaseous inclusions in quartz crystals found in concretions from diagenetically altered Jurassic sediments from S-E France. The gas compositions vary as a general function of the diagenetic grade of the enclosing sediments. Two major types of gas inclusions were found, a wet gas in the western part of the basin and a dry gas in the eastern part. The proportions of CH4, C2H6, C3H8, CO2, H2S and N2 were determined to within one percent of the amount present. The gas mixtures and fluid phase assemblages indicate that these materials were entrapped during the evolution of the organic and mineral rock assemblages induced by increases of temperature and pressure. There is no evidence for change of the organic material posterior to its entrapment as a fluid inclusion. UV fluorescence optical observations indicate that organic liquids are present in the primary inclusions and also in secondary inclusions situated in healed cracks. These secondary inclusions are found in the whole area. UV fluorescence measurements indicate that this trapped material could be an extract from a more evolved organic material than that found in primary inclusions. These secondary inclusions could have been formed during tectonic event of the Alpine orogenies.

Scattering characteristics of crystallites in fluoride optical fibers

This paper evaluates the scattering loss in ZrF(4)-based fluoride optical fibers that is caused by ZrF(4) and ZrO(2) crystallites. To determine this, efficiency factors of each of these crystals are calculated. We make clear that the presence of ZrO(2) crystals of the order of a submicron smaller than 0.2 microm in diameter effectively elevates the Rayleigh scattering factor as the particle number increases. Scattering loss characteristics in current fluoride fibers are also discussed. In addition, ZrO(2) microcrystals in fluoride fibers are identified for the first time using Raman microprobe analysis. It is concluded that ZrO(2) microcrystals cause serious extrinsic scattering loss in current ZrF(4)-based fluoride fibers.

Ge-Si alloy microstructure fabrication by direct-laser writing with analysis by Raman microprobe spectroscopy

Micron-dimension structures of germanium-silicon alloys of various compositions are formed by several direct-laser writing techniques, including pyrolytic deposition of silicon from silane on laser-melted germanium substrates and codeposition from silane/germane mixtures on different absorbing substrates. In situ composition analysis of these polycrystalline alloy microstructures is performed by Raman microprobe analysis. The measured Raman shifts and widths of the laser-deposited alloys are found to be in better agreement with published Raman data on germanium-silicon alloy films than with the Raman data on alloy bulk solids. In the codeposition of alloys, the decomposition of germane to form Ge is observed to be about six times faster than the decomposition of silane to form Si, independent of the silane/germane ratio, laser power, and substrate type.

Applications of the laser Raman microprobe RAMANOR U-1000 to hydrothermal ore deposits; Carlin as an example

The laser Raman microprobe has been used effectively in the identification of polyatomic gases, complex ions, and daughter crystals in fluid inclusions in a variety of host rocks (e.g., Dhamelincourt et al., 1979a; Rosasco and Roedder, 1979). This is a generally nondestructive, in situ, semiquantitative analytical technique in which a monochromatic laser beam is focused into a sample. The spectrum resulting from the inelastically scattered radiation indicates the chemical speciation of the irradiated sample. Although laser Raman microprobe analysis is not very effective for brines composed of simple salts, the nonelectrolyte components of hydrothermal fluid inclusions can be readily analyzed. Raman spectroscopy also provides important information, on a microscale, for solid phases in the assemblage. Fluid inclusions in quartz and calcite from several types of samples from the disseminated gold deposit at Carlin, Nevada, were studied petrographically and analyzed by microthermometry and Raman spectroscopy. The laser Raman microprobe was used to scan for CO 2 , CO, N 2 , H 2 S, and CH 4 + or - H 2 O. The semiquantitative microprobe analyses confirmed the presence of three-phase inclusions containing water and different amounts of CO 2 , one-phase inclusions of high-density CH 4 -dominated fluid, and very weak aqueous brines. Very minor H 2 S was detected in a CO 2 -H 2 O inclusion and small amounts of CO 2 were detected in some of the CH 4 -dominated inclusions. These gases may have affected ore deposition. In any event, their identification is necessary for correct estimations of pressure to be derived from homogenization temperatures of the fluid inclusions. The laser Raman microprobe provides more than compositional data. For instance, the exact spectral position and shape of the CH 4 peak indicate the internal pressure, even in inclusions too small ( 2 polymorphs anatase and brookite (both present) in hydrothermal quartz deposits at Magnet Cove, Arkansas. The ability of the laser Raman microprobe to provide pinpoint analyses has many advantages over bulk extraction methods, which mix the volatiles from separate generations of fluids and may also produce chemical artifacts.

Direct-laser writing of silicon microstructures: Raman microprobe diagnostics and modeling of the nucleation phase of deposition

Two topics vital to the analysis and applications of direct-laser writing of silicon microstructures are addressed here: optical diagnostics and modeling. The use of real-time and postprocessing Raman microprobe analysis of laser-written doped polysilicon microstructures on CMOS gate arrays is shown to be a useful diagnostic tool. Also, the results of a Monte Carlo simulation of adatom migration and desorption are applied to the study of nucleation effects in direct-laser writing, with specific reference to the deposition of silicon.

Raman microprobe analysis during the direct laser writing of silicon microstructures

Raman microprobe techniques are used for the first time as a real-time probe during local direct laser writing and also as an in situ probe after writing. The Stokes–Raman emission observed during pyrolytic deposition of micron-dimension structures of silicon on germanium and vitreous carbon substrates is found to be weaker, more asymmetric, and to peak at a smaller Raman shift than the corresponding spectrum of the same structure similarly probed in situ after deposition. Results of detailed post-deposition Raman analysis of these silicon microstructures are presented and compared to the Raman spectra of oven-heated silicon. Potential applications of these techniques are discussed.

Comparison of Matrix Variation in Nicalon (Sic) Fiber Reinforced Composites

ABSTRACTThe high-temperature behavior of NICALON fabric is discussed. Three fabric reinforced composites are described that use NICALON fabric to take advantage of its oxidation and erosion resistance. The matrix materials used were phenolic resin, pyrolytic carbon and beta-silicon carbide. Each composite was subjected to an erosive environment at 2755 K. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), and laser Raman microprobe analysis (LRMA) were used to characterize the raw materials, the unfired composites, and the erosion tested composites. These analyses concentrated on the fiber/matrix interaction and the effect of erosion on each component of the composite.

Raman microprobe analysis of stress in Ge and GaAs/Ge on SiO2-coated Si substrates

Stress and strain in single-crystal Ge and GaAs/Ge films grown on SiO2-coated Si substrates have been investigated through the Raman microprobe analysis. The Ge film is found to be subject to a tensile stress of (3.4–6.1)×109 dyne/cm2 and a strain of (2.4–4.3)×10−3 without distinguished spatial variation within a SiO2 island. The stress agrees well with that evaluated from the GaAs electroluminescence spectral shift with the deformation-potential model. The strain can be attributed dominantly to the thermal expansion difference between the Ge and the substrate Si. A large Raman spectral shift to the lower frequency side and a large linewidth for Ge have been observed in the seeding opening region, which represents Ge lattice disorder in this region.