Focusing monochromator and imaging-plate camera for grazing-incidence diffraction studies of thin films

A multiple-imaging-plate detector system and focusing monochromator have been developed and successfully applied to the time-resolved study of phase transitions in Langmuir-Blodgett films by grazing-incidence X-ray diffraction (GIXD). The monochromator described here combines fixed-exit-beam height with sagittal focusing of the second crystal. The design is similar to that of Matsushita et nl. [Matsushita, Ishikawa & Oyanagi (1986). Nucl. Instrum. Methods, A246, 377-379], with the exception that the motion of the first crystal is achieved via a computer-controlled X-Y translation table rather than a set of cams. The second crystal is a ribbed Si(111) wafer mounted in a four-point bending mechanism. The first reported application of imaging plates to a GIXD study was carried out by our group and proved to be very successful in the determination of thin-film structure [Foran, Peng, Steitz, Barnes & Gentle (1996). Langmuir, 12, 774-777]. To extend the capabilities of this system, an imaging-plate camera was designed and built which can accommodate up to 13 imaging plates (40 x 20 cm) inside the vacuum chamber of the main diffractometer at the Australian Beamline at the Photon Factory

On the feasibility of establishing the provenance of Australian Aboriginal artefacts using synchrotron radiation X-ray diffraction and proton-induced X-ray emission

Museums and galleries in Australia have extensive collections of Aboriginal artefacts in their custody. In particular, the National Museum of Australia and the National Gallery of Australia are custodians of works of very considerable significance, in both cultural and financial terms. Art fraud can occur, documentation relating to artefacts can be mislaid, or the artefacts can be incorrectly filed. Because of this, it has become essential to establish protocols for the objective determination of the provenance of artefacts through scientific tests. For the work reported here we are concerned with the comparison of very small quantities of materials, paint scrapings from artefacts. Scrapings from artefacts of unknown provenance are compared with those from artefacts of known provenance, and the database established using an extended set of analytical techniques by Kubik. We describe here our use of synchrotron radiation X-ray diffraction (SR-XRD) to determine the mineral phase compositions of very small amounts of pigment material (<50 μg), and the use of PIXE to give their atomic compositions to a threshold level of 1 ppm for similar masses of material

The effect of laser excitation on the Raman microspectroscopy of nanoindentation-induced silicon phase transformation

It is well established that silicon undergoes a series of phase transformations when subjected to the pressure of nanoindentation. Phase transformations in silicon are studied using diamond anvil apparatus. The effect of the high pressure is an increase in density in diamond-cubic Si-I and as a result an unstable metallic phase of silicon (Si-II) is formed. This rapidly transforms to other phases upon pressure release. Depending on the rate of pressure release, rhombohedral (r8) Si-XII, body-centered-cubic (bc8) Si-III and/or the amorphous phase (a-Si) can occur. Raman spectroscopy is particularly useful for the characterization of the many different phases of the transformed silicon. A comparison of Raman spectra obtained with different laser wavelength excitations has been undertaken to examine whether source dependent effects occur during the characterization of the silicon phases. Preliminary results are presented here

Raman analysis of iron gall inks on parchment

For centuries, iron gall inks were the most commonly used black inks in the Western world. Many documents, manuscripts and artworks are now suffering varying degrees of degradation due to the corrosive nature and colour instability of the ink. Raman microspectroscopy has been used to analyze historic iron gall inks in situ on parchments, iron gall inks prepared following traditional recipes, separate ink components and various combinations of components. FT-Raman spectroscopy was also applied to the latter samples. This research investigates the optimization of the technique and some problems encountered in the collection of Raman spectra for iron gall inks. Preliminary results from sample analysis are presented