The unique electronic properties of single-walled carbon nanotubes (SWNTs) have sparked interest for using such nanomaterials in the nuclear industry and within radiation detection devices. To explore the application of SWNTs in the nuclear industry, it was first deemed necessary to study how SWNTs respond to the two main types of radiation occurring in nuclear environments, neutrons and gamma rays. SWNT samples were irradiated in the High Flux Isotope Reactor (HFIR) at Oak Ridge National Laboratory with neutrons and gamma rays at incremented lengths of time allowing for multiple fluence intensities to be received by the samples. After irradiation, Raman spectroscopy was used to monitor the damage incurred from neutron and gamma irradiation. It was found that disorder within the SWNT lattice network increased with increasing irradiation intensity. The results indicated that the gamma irradiation was causing the majority of the damage with little to no damage caused by the neutron irradiation. Further investigation showed that the non-linearity of the disorder increase with increasing irradiation intensity was typical of sample doping instead of the expected particle impacts. It was concluded that the gamma irradiation was generating dopants within the SWNTs by the process of water radiolysis. Water vapor trapped between the SWNT film layer and the substrate that the film layer was placed on was identified as the source of the sample dopants. Although unexpected, the results from this experiment have provided insight into a potential gamma radiation detection technique using SWNTs that has never been considered until now. / Master of Science

No / The FT Raman spectrum of caffeine was analysed along with that of its demethylated analogues, theobromine and theophylline. The similar but not identical structures of these three compounds allowed a more detailed assignment of the Raman bands. Noticeable differences in the Raman spectra of these compounds were apparent and key marker bands have been identified for the spectroscopic identification of these three compounds.

No / Calcium and magnesium carbonates are important minerals found in sedimentary environments. Although sandstones are the most common rock colonized by endolith organisms, the production of calcium and magnesium carbonates is important in survival strategies of organisms and as a source for the removal of oxalate ions. Extremophile organisms in some situations may convert or destroy carbonates of calcium and magnesium, which gives important information about the conditions under which these organisms can survive. The identification on the surface of Mars of 'White Rock' formations, in Juventae Chasma or Sabaea Terra, as possibly carbonate rocks makes the study of these minerals a prerequisite of remote Martian exploration. Here, we show the protocol for the identification by Raman spectroscopy of different calcium and magnesium carbonates and we present a database of relevance in the search for life, extinct or extant, on Mars; this will be useful for the assessment of data obtained from remote, miniaturized Raman spectrometers now proposed for Mars exploration.

No / Morphological biosignatures (features related to life) and associated terrestrial sedimentary structures that provide possible sampling targets for the remote astrobiological exploration of planets have been analysed using Raman spectroscopic techniques. The spectral data from a suite of samples comprising crypto-chasmoendoliths, preserved microbial filaments and relict sedimentary structures comprise a preliminary database for the establishment of key Raman biosignatures. This will form the basis for the evaluation of prototype miniaturised instrumentation for the proposed ESA ExoMars mission scheduled for 2013. The Raman spectral biosignatures of carotenoids and scytonemin, organic biomolecules characteristic of the cyanobacterial colonisation of geological matrices and biogeologically modified minerals are also identifiable in the sedimentary specimen materials. The results of this study demonstrate the basis of the molecular recognition of extinct and extant exobiology that will feed into the elemental structural analyses of morphological structures provided by associated SEM, XRD and laser-induced breakdown spectroscopy (LIBS) techniques on robotic analytical landers.

No / Violacein is a bisindole pigment occurring as a biosynthetic product of Chromobacterium violaceum and Janthinobacterium lividum. It has some structural similarities to the cyanobacterial UV-protective pigment scytonemin, which has been the subject of comprehensive spectroscopic and structural studies. A detailed experimental Raman spectroscopic study with visible and near-infrared excitation of violacein produced by C. violaceum has been undertaken and supported using theoretical DFT calculations. Raman spectra with 514 and 785 nm excitation of cultivated cells as well as extracts and Gaussian (B3LYP/6-311++G(d,p)) calculations with proposed molecular vibrational assignments are reported here.

No / The impregnation of items of clothing with drugs of abuse that are then smuggled through airports and ports of entry is a growing problem for law enforcement. This work describes the application of portable Raman spectroscopic techniques for the analysis of a range of natural and artificial fibre items of clothing impregnated with drugs of abuse. Textile pieces were soaked with the solutions of the drugs then left overnight to dry prior to spectroscopic examination. The feasibility of detection of the characteristic Raman spectral bands in the presence of background matrix signals is demonstrated, even for dyed clothing. Definitive evidence for contamination of the items of clothing concerned can be acquired within 20-25 s, without any form of sample pre-treatment or extraction being necessary. The feasibility of automatic spectral recognition of such illicit materials by Raman spectroscopy has been investigated by searching a database stored on the spectrometer computer and the use of principal component analysis. Copyright (c) 2014 John Wiley & Sons, Ltd.

No / The Raman spectra of two historical specimens of human hair attributed to the engineer Robert Stephenson and scientist Sir Isaac Newton, preserved in private collections are reported. Comparisons are made with the Raman spectra of modern hair specimens and with hair from archaeological excavations. The hair spectra collected with a laser excitation of 785 nm are of a better quality than those collected using 1064 nm. The historical hair specimens are remarkably well-defined spectroscopically in terms of the amide I vibrational mode and the ν(SS), ascribed to a predominantly gauche–gauche–gauche CSSC conformation. The contrast with degraded hair specimens recovered from archaeological excavations is striking. The presence of a weak feature near 2590 cm−1 in the hair samples attributed to a ν(SH) vibration could be indicative of a reduction process operative on the CSSC cystine keratotic linkages and a possible origin of this is bacterial biodegradation identified histologically. This study demonstrates the molecular information available from non-destructive Raman spectroscopic analysis from single hair shafts or small bundles of fibres which complements information available from histological and destructive analytical techniques for rare biological specimens subjected to conservation or curation procedures in museums or private collections.

No / There is developing interest in the analytical use of human hair from archaeological contexts in key research areas such as DNA, trace elemental and isotopic analyses. Other human tissues, especially bone, that have been used for trace element, isotopic and DNA analyses have had extensive study concerning their diagenesis, but this has not been done for hair. Consideration must be given to the complex interaction of hair with its buried environment, thereby laying a firm basis for the use of hair in future research. Since human hair is known to survive under a diverse range of environmental conditions, a pilot study has investigated the basic processes of hair degradation, using samples from different climatic zones and burial types. Variation in the degree of preservation of archaeological hair was characterized by light microscopy, electron microscopy, and FT-Raman spectroscopy, relating morphological change of the surface and internal structure of hair to its biochemical integrity. The results demonstrate a breakdown of cortical cell boundaries and disruption of the cuticular layering, coupled with infiltration of material from the burial matrix that suggests a progressive loss of cohesion that is in part due to microbiological activity. Medullated hair is shown to be more susceptible to physical breakdown by providing two routes for microbial and environmental attack. At the molecular level the proteinaceous component undergoes alteration, and the S-S cystine linkages, responsible for the strength and resilience of hair in living individuals, are lost.

No

No description available.