Fine-scale determination of OH in radiation-damaged zircon using Synchrotron Fourier Transform Infra Red spectroscopy (FTIR) and Attenuated Total Reflectance (ATR)

The crystal structure of zircon is gradually broken down by the decay of small amounts of U and Th present in zirconium lattice sites. It has been observed that, with increasing radiation damage, zircon can lose radiogenic Pb and at the same time gain water from the environment. The disturbance of the U-Pb system is a major problem in zircon U-Pb geochronology. Water penetration appears to be an important factor in Pb loss but to explore this further a technique is needed for making fine-scale in situ measurements of water on the polished surface of radiation damaged zircons. Our research has shown that Attenuated Total Reflectance Fourier Transform Infra Red (ATR-FTIR) spectroscopy with a synchrotron source and thermal analysis can be successfully used to map the fine-scale distribution of OH/H2O in radiation damaged zircons. The radiation damaged zircons were found to have an OH/H2O content varying from 0.4% to 5% with maxima occurring in the heavily damaged (metamict) zones noted for their disturbed U-Pb systems. Whilst thermal analysis confirmed the presence of OH and possibly H2O the infrared spectra did not distinguish between them

Leaching of a low-grade, copper-nickel sulfide ore: 2. Impact of aeration and pH on Cu recovery during abiotic leaching

The conditions under which copper was retained and re-distributed in a test heap of pyrrhotite-rich, copper-nickel sulfide ore were investigated in abiotic column leaching tests. It was determined that acidity plays a key role in maximising copper recovery. During passage through the ore bed, when the leachate pH rose to >2.3, copper ions previously released to solution through the oxidation of chalcopyrite were retained by adsorption on, or reaction with, ore minerals. Lack of aeration (limited oxygen) had only a small impact on copper recovery, in association with a favourable pH environment. Possible reaction mechanisms are discussed. The results indicated the need for careful acid management in the operation of heaps of pyrrhotite-rich ores such as complex copper-nickel sulfide ores

Leaching of a low-grade, copper-nickel sulfide ore. 3. Interactions of Cu with selected sulfide minerals

Interactions between copper ions and selected sulfide mineral concentrates were investigated in flask and column tests under conditions relevant to heap leaching in order to understand why copper recovery from a copper-nickel complex sulfide ore was significantly less than nickel recovery. Both pyrrhotite and pyrite were found to play roles in copper deposition from sulfate solutions in the range pH 1-5. The non-oxidative dissolution of pyrrhotite, previously reported to occur under acidic conditions of low oxygen availability, was also found to occur in a well-aerated system. Soluble copper reacted with the generated hydrogen sulfide to form copper sulfide, mainly covellite at pH >2.3 and its re-dissolution required acid, oxygen and a strong oxidant such as ferric ion. While significant copper also precipitated from copper sulfate solutions pH N3 in the presence of pyrite, the brochantite which was formed was readily re-dissolved at pH <3. The poor recovery of copper experienced in a test heap of copper-nickel sulfide ore was attributed to the presence of pyrrhotite and the rise in pH as the leachate percolated through the heap bed. The copper would only be recovered if acidic, oxidising conditions were restored in the heap

Enhancing the evidential value of textile fibres: Part 1: Development of a spectral database and evaluative comparison strategy

In numerous major crime cases undertaken at our laboratory the recovery of large numbers of fibres ( &gt; 1000), particularly in cases with no known source, presented several challenges. These included the inability to effectively manage the data (i.e. combination of MSP spectra, microscopic characteristics, composition, etc.) and perform comparisons in an efficient manner. To address these challenges, and in response to a growing need for performing fibre comparisons, we developed a database of textile fibre microspectrophotometric (MSP) spectra. The database, designed to compare MSP spectra using a modified Pearson method of correlation, currently contains over 20,000 normalised and first derivative spectra of casework, validation and reference textile fibres. A comparison strategy for cases with a large number of questioned samples was devised, involving identification of critical fibres in the casework data set, development of preliminary fibre groups classified according to their corresponding/similar MSP spectra, and verification of the preliminary groups via brightfield and fluorescence comparison microscopy. The database has successfully been utilised for proficiency trials and casework with small questioned fibre sets. Furthermore, in a case involving a larger dataset ( &gt; 4000 “unknown” fibres) the database assisted in the efficient classification of 156 distinct groups of interest, highlighting its utility in providing investigative leads for the identification of potential sources of the recovered fibres

p-Dimethylaminobenzaldehyde: preliminary investigations into a novel reagent for the detection of latent fingermarks on paper surfaces

A new method for the detection of latent fingermarks on paper surfaces using p-dimethylaminobenzaldehyde (DMAB) is described. The method is based upon the reaction of DMAB with the amino acids present in the latent fingermark to give a yellow-brown impression that is photoluminescent when illuminated with a high intensity filtered light source at 490 nm and viewed through orange goggles (OG550). A wet contact method proved effective on non-fragile porous substrates such as white photocopy paper and various other substrates, while a dry contact (solventless) method afforded development on thermal paper. Luminescence spectrophotometry of developed L-alanine, glycine and L-serine spots on paper was used to confirm that DMAB was reacting with amino acids in the latent fingermark

Synchrotron FTIR characterisation of automotive primer surfacer paint coatings for forensic purposes

Synchrotron FTIR microspectroscopy was used to characterise and assess the chemical diversity of electrocoat primer, primer surfacer and basecoats of automotive paint samples from 75 vehicles representing a range of international car manufacturers. Significant diversity was found in the synchrotron FTIR data from the primer surfacer coats. Classification using principal component analysis revealed 14 discrete groups, which could be associated with the country of manufacture, the specific manufacturer and manufacturing plant, the year of manufacture of the vehicle and in some instances the number of layers in the paint system. The model generated from the primer surfacer was significantly more discriminating than a previous model generated from FTIR analysis of clear coats of the same vehicles. Analysis of the primer surfacer also avoids issues of possible environmental degradation and component migration seen with FTIR analysis of automotive clear coats. Providing such information concerning vehicle origin would aid in the development of investigative leads from the analysis of questioned automotive paint samples located at the scene of a crime or on the body/clothing of a hit and run victim

Sequencing of a modified oil red O development technique for the detection of latent fingermarks on paper surfaces

A modified detection sequence is presented for the recovery of latent fingermarks on porous substrates. 1,2-Indanedione, Oil Red O (ORO) in propylene glycol, and physical developer (PD) were successfully used to develop recently deposited latent fingermarks when applied in the order given. The incorporation of ORO into the detection sequence increased the number of latent fingermarks that were detected compared to using the standard sequence of 1,2-indanedione followed by PD only

Investigations into the initial composition of latent fingermark lipids by gas chromatography-mass spectrometry

A more comprehensive understanding of the variability of latent fingermark composition is essential to improving current fingermark detection capabilities in an informed manner. Gas chromatography–mass spectrometry was used to examine the composition of the lipid fraction of latent fingermarks collected from a population of over 100 donors. Variations in the appearances of chromatograms from different donors were apparent in the relative peak sizes of compounds including free fatty acids, squalene, cholesterol and wax esters. Principal component analysis was used as an exploratory tool to explore patterns in this variation, but no correlation to donor traits could be discerned. This study also highlights the practical and inherent difficulties in collecting reproducible samples

Synchrotron infrared microspectroscopy study of the orientation of an organic surfactant on a microscopically rough steel surface

The performance of organic surfactants as corrosion inhibitors is influenced by the mechanism of adsorption and the resulting molecular orientation on the substrate. The molecular orientation of 1-dodecylpyridinium chloride (DPC) deposited on non-corroded 1030 mild steel and after corrosion in a carbon dioxide environment has been investigated using synchrotron infrared microspectroscopy. DPC mitigates the corrosion process by adsorbing at the steel surface and forming a protective layer. Infrared spectra analogous to polarized grazing angle spectra were obtained from a microscopically rough surface using a synchrotron source. The appearance of negative and positive absorption bandsin the spectra, when using synchrotron radiation, is discussed in terms of the optical system used. The presence of the DPC surfactant at the steel surface is shown by the CH2 and CH3 infrared absorption bands of the aliphatic chain of the DPC molecule. The infrared spectra provide direct evidence on the orientation of DPC at the steel substrate. The aliphatic chain of the surfactant is tilted orthogonally, but not perpendicular to the substrate plane. The absence of significant absorption bands characteristic of the pyridinium ring of DPC indicates its orientation parallel to the substrate plane, and an adsorption mechanism involving pi-bonding with the steel. This study demonstrates the applicability of synchrotron infrared microspectroscopy to the investigations of thin organic films on microscopically rough steel surfaces, and can facilitate further investigations of thin films on metallic surfaces and monolayer studies in general

Preliminary investigations into a commercial thermal fingerprint developer for the visualisation of latent fingermarks on paper substrates

The Thermal Fingerprint Developer (TFD-2) developed by Foster and Freeman is the first commercially available instrument to solely utilise heat treatment to visualise latent fingermarks. The chemical-free TFD-2 was able to develop latent fingermarks on a variety of substrates. The manufacturer’s guidelines with regard to the optimal treatment settings were suitable for the more common substrates such as white copy paper; however, new protocols were required for the treatment of thermal paper. TFD-2’s ability to develop these samples and its use in sequence with traditional chemical reagents, such as 1,2-indanedione and physical developer, was demonstrated. The thermal developer may offer quick and easy heat application options for existing fingermark development reagents. It was found, however, that the TFD-2 developed samples lacked the detail and contrast afforded by conventional amino acid sensitive reagents under most conditions