The spectra of photoluminescence (PL) from a zinc oxide (ZnO) crystal included an unusual feature of an ultraviolet (UV) emission at a higher energy than the ZnO interband transitions. The energy of this UV emission varied with temperature and included two discontinuous energy steps in the temperature range from 78 to 700K. The temperature values of the steps match phase transition temperatures of ethanol. Ethanol was used during sample cleaning and can be trapped in the form of nanoparticles inclusions. Both the intrinsic and defect site, PL signals have different temperature dependencies from those of bulk crystals, as seen during radioluminescence. The origins of the changes are discussed.

Progress in electronics and optics offers faster computers, and rapid communication via the internet that is matched by ever larger and evolving storage systems. Instinctively one assumes that this must be totally beneficial. However advances in software and storage media are progressing in ways which are frequently incompatible with earlier systems and the economics and commercial pressures rarely guarantee total compatibility with earlier systems. Instead, the industries actively choose to force the users to purchase new systems and software. Thus we are moving forward with new technological variants that may have access to only the most recent systems and we will have lost earlier alternatives. The reality is that increased processing speed and storage capacity are matched by an equally rapid decline in the access and survival lifetime of older information.This pattern is not limited to modern electronic systems but is evident throughout history from writing on stone and clay tablets to papyrus and paper. It is equally evident in image systems from painting, through film, to magnetic tapes and digital cameras. In sound recording we have variously progressed from wax discs to vinyl, magnetic tape and CD formats. In each case the need for better definition and greater capacity has forced the earlier systems into oblivion. Indeed proposed interactive music systems could similarly relegate music CDs to specialist collections.The article will track some of the examples and discuss the consequences as well as noting that this information loss is further compounded by developments in language and changes in cultural views of different societies.

Luminescence techniques are powerful and sensitive probes to study imperfections, impurities and modifications of insulating materials. They are used in a wide range of disciplines from condensed matter physics to archaeology and mineralogy and the methods have developed over nearly a century. Early equipment was often not quantitative and data were collected in formats that were difficult to process and manipulate, and so signals were frequently presented in terms of the initial signals without corrections for equipment spectral sensitivity. Unfortunately not only did this distort the information but often it resulted in incorrect interpretations. Further, the incorrect data handling has persisted into modern usage both by physicists and those in other fields who merely use luminescence as a sensitive technique. Several main types of problem are considered. These include temperature errors in thermoluminescence dosimetry; subtleties in the signal intensity corrections for the responses of both the spectrometer and detectors; grating polarization effects; sample anisotropy; and common errors in spectral deconvolution, especially failure to transform from wavelength to energy plots.

Photomultiplier tubes are widely used detectors of low level light signals; however their performance is often limited, especially at long wavelengths. Input signals are reduced both by surface reflection and by transmission through the photocathode layer. Earlier methods of overcoming these weaknesses are summarized. New predictive modelling of the reflectivity and absorption reveals dependencies that are a function of angle of incidence, cathode thickness and polarization. Improvements on normal usage using extremely simple and low cost techniques are effective. These are demonstrated using retrofits that can improve the overall sensitivity of many types of photomultiplier. Examples include a simple external conical torch reflector, which has raised the efficiency of an S20 multialkali photocathode by between 20 to 10% across the blue to red spectral range. A second example, of a semi-cylindrical glass coupler, improved the absorption efficiency by exploiting 60 degree, rather than normal incidence of the light. Enhancements are up to 500% at longer wavelengths. Such gains are particularly valuable as this is the region of lowest quantum efficiency for the standard operation of the tubes.

Luminescence excited during ion beam bombardment offers information on both stable and metastable defect and impurity sites, and it is a sensitive and powerful analytical tool for insulating materials and semiconductors. Most studies so far have focused on visible and UV emission spectra as the spectra reveal information on the formation and types of defect sites. The modifications are dependent on ionisation density, and synergistic effects with nuclear collision damage. There is thus the ability to track defect production and amorphisation of crystalline hosts. Further, ion beam excited luminescence is equally a useful probe for studying nanoparticle growth. Such data can be obtained at different implantation temperatures or combined with other thermal treatments. Pulsed ion beams have the potential to reveal variations in defect formation by lifetime resolution of the signals. However, there is far greater analytical potential which has not been widely developed. The current article will describe how to extend the effects of lifetime resolution; to detect phase transitions, both stable and transient; and the opportunities which arise from combining the ion beam induced luminescence signals with simultaneous excitation of the materials with photons, electrons or X-rays. The combination of two methods can differ from the sum of separate excitation irradiations and so offer details on metastable structures related to ion implantation. Site specific probes using rare earth doped materials during implantation to form laser waveguide structures can track relaxations of both the guide and boundary regions. The measurement of ion beam luminescence spectra and lifetime data over a wide temperature range have historically been under exploited. Parallel data from optical absorption taken during implantation can be similarly informative. Benefits from all such measurements will be discussed.

speed, fibre optic communication or cost per CCD pixel often follow a smooth logarithmic improvement per year. This seems desirable, but progress is frequently only achievable by introduction of new software, different types of storage media or new operating conditions. Consequently technologies become outdated. For transient information this is unimportant, but for long term storage and archiving of information, images, photographs etc, there is an inevitable loss of earlier records. This is not a new phenomenon as even information on stone or clay tablets has decayed or been lost, either by physical decay of storage materials or loss of understanding because of changing language and cultural nuances. Examples emphasise how technological progress has speeded up information decay and loss. Since logarithmic "laws" have been proposed to describe the trends for electronic improvements, one may consider if equivalent trends apply to information loss. It appears that one may propose that the product of three factors is roughly constant. These are the time needed to write the new information; the quantity of information stored, and the average survival time of the information before the storage medium has decayed or is obsolete. The reality of such a "law" is that, whereas we may currently have records and photographs from many earlier generations, our rapidly stored electronic data may be lost within a few years, and certainly will have vanished in a readable form for the next generation.

A new family of luminescent materials has been prepared by hydrothermal techniques. The materials are derived from the novel organically templated framework structure [C2N2H10](0).(5)[Y2F7]. This structure type consists of a three-dimensional yttrium fluoride framework incorporating two similar, but crystallographically distinct, yttrium sites. The lanthanide analogues [C2N2H10](0.5)[Ln(2)F(7)] have been prepared for Ln = Nd3+ and Eu3+-Lu3+, and the crystal structure of [C2N2H10](0.5)[Yb2F7] is reported in detail. Photo-, cathodo- and radioluminescence measurements have been carried out on a range of Gd3+-, Eu3+- and Tb3+-doped derivatives of [C2N2H10](0.5)[Y2F7], all of which show characteristic luminescence emissions.

The easy and non-destructive fluorescence method for quantification of early changes in biological tissues improves the possibilities of the clinical research and diagnostics. Developments in this area are moving very rapidly in part because of advances in the technology and in part because of the numerous successful examples which are appearing. New family of photomultiplier tubes with a high detection sensitivity for near-infra red light (700-900 nm) were developed as a result of project IMPECABLE, which are valuable tools for early diagnosis of cutaneous pigmented melanoma using long-wave fluorescence dyes. Several phthalocyanines that are promising fluorophores for photodiagnosis of cutaneous malignant melanoma have been studied in different solvents for concentrations from 10-5 to 10-15 mol. Argon pumped dye laser as an excitation source was used. Three different wavelengths (613, 633 and 660 nm) in the red region, corresponding to first absorption peak, minimum of the absorption and near to the Q-band maximum of Pcs were applied. Fluorescence signals in the region of 700 to 800 nm were detected using spectrometric systems (Perkin-Elmer, UK-with conventional PMT as a detector, and PC2000, Ocean Optics, USA-with CCD-array as a detector) and a newly developed red-sensitive PMT. Detectable signal from other spectrometric systems was obtain up to 10-8 mol concentrations, which could be used for significant reduction of concentrations applied for in vivo applications. Fluorescence is a highly sensitive method of distinguishing between healthy and unhealthy tissue. The results demonstrate that extremely low concentrations of photosensitizers could be used to determine initial stages of melanoma. This application of PMT detectors will reduce extremely the negative side effects of higher concentrations of these drugs applied in the skin tissue. One can achieve high accuracy in the determination of pigmented malignant melanoma lesions with wide clinical applications.

Pulsed laser annealing has been used to modify the surface and refractive index profiles of ion implanted waveguides formed in Nd:YAG and LiNbO(3) crystals. Improvements are seen from reduced losses in the niobate guides and by enhanced index confinement in the garnet In both materials these beneficial changes require optimisation, since prolonged laser treatments can introduce surface damage in the niobate, and/or emphasise the problems of surface instability on the garnet Overall the improvements in waveguide loss and surface quality are encouraging New data are discussed for loss and refractive index profiles, and compared with existing data on surface second harmonic generation quality analysis. Optimisation of the laser pulse power, and the number of pulses are predicted to improve guide quality in both materials, particularly for guides implanted with more than one energy, which will increase the initial width of the guide boundary.

Three dimensional (3D) thermoluminescence (TL) spectra of two yttrium orthovanadate (YVO4) single crystals grown from YVO4 melt by the Czochralski (CZ) technique and one additional YVO4 crystal pulled from lithium-metavanadate (LiVO3) flux by the top seeded solution growth (TSSG) method were investigated after x-ray irradiation. The TL spectra were recorded in the 200–800 nm wavelength and 20–300 K temperature ranges before and after annealing of the crystals in an oxygen atmosphere. In spite of the different growth conditions the measured 3D TL spectra of the CZ samples show similar TL characteristics. The main TL emission appears around 450 nm, and between 200 and 250 K. Further weak emissions were also detected at 570, 600, 650, and 710 nm wavelengths, which might be attributed to unwanted impurities. The TL spectrum of the TSSG crystal markedly differs from that of the CZ crystals. On one hand the major TL appears at lower temperatures whereas on the other hand the emission spectrum exhibits a broader band around 500 nm, while the weak bands between 500 and 700 nm could not be detected. Based on these observations the different defect structures in YVO4 crystals are discussed in the article emphasizing that 3D TL measurement is a useful practical tool for the characterization and identification of YVO4 crystals grown by different methods.

This paper reports the thermo- and radio-luminescence of transition metal-doped natural beryls. The luminescence was measured between 20 and 300K. Mn3+ and Cr3+ have been found to activate the thermoluminescence with a high degree of efficiency. Comparison of beryl:Ni, beryl:Co and aquamarine emission spectra with that of quartz suggests that in some respects the beryl behaves as though it is a quartz and this has been concluded to follow from similarities in the framework nature of both lattices.

Inorganic dusts from different herbs and spices are investigated in this study using both standard thermoluminescence measurements of integrated intensity versus temperature and measurements of the thermoluminescence emission spectra (intensity as a function of both temperature and wavelength). The importance of particular minerals in the composition of glow peaks detected is discussed. Thermoluminescence emission spectra of the samples studied reveal (i) the presence of a broad high-intensity signal in the red to infra-red spectral region in all irradiated polymineral dusts; (ii) the hitherto unsuspected importance of calcite in the polymineral fractions of the dust; (iii) the existence of high-temperature unbleachable peaks from the silicate fraction in the orange to near infra-red portions of the emission spectrum; and (iv) the potential for quantification of absorbed dose. Discrimination between irradiated and un-irradiated spices appears to be feasible.