Nina P. Zvezdova

Micron spatial resolution X-ray image plates with non-erasing reading

Abstract New silverless radiophotoluminescence substances NaCl(Me) and LiF(Me) are proposed and tested as X-ray image detectors. Their spatial resolution is not worse than 2 μm and they allow one to register X-ray pictures with a dynamic range of about 5000. A stored X-ray image can be read out many times by photoluminescence measurements under UV excitation. The image can be erased completely by heating the substances up to a temperature of 400°C during 0.5 h.

High-resolution x-ray microscopy for biological objects

New radiophotoluminophores are used for x-ray microscopy. The material provides the resolution 2 micrometers and dynamic range of registration equal to 104. Some problems of using luminophores in rentgenography of biological objects are discussed. The examples of the images are given.

Investigation of structure of UV luminescence centres in pure alkali halide crystals with SR

Abstract The nature of the thermal defects in alkali-halide crystals was studied by the X-ray excited UV luminescence and XEOL. The dependence of the luminescent intensity on the heating time and temperature and X-ray dose was observed. The structure of the defects was determined by XEOL. It has been suggested that luminescent centres are the pair defects of anionic sublattice of crystal.

Effect of surface implantation of impurities on LiF crystal luminescence spectra

Photoluminescence and excitation spectra of radiation-induced defects in LiF single crystals with modified surface were studied. Both the change of host defect formation efficiency and arising of new spectral bands in consequence of impurity effect were demonstrated.

Use of EXAFS- and optical spectroscopy for analysis of NaCl-Ni,Cu crystal structure modification resulting from X-irradiation

On the basis of the optical and FLEXAFS spectral data the conclusion about influence of copper and nickel impurities interaction on spectral characteristics of nickel clusters contained in a NaCl-Ni, Cu crystal is derived. The distinction in spectra of excitation can be caused both competitions in absorbency and distortion of the explored defect structure.

Transformation of the luminescent centres in KCl–In crystals under synchrotron radiation

Abstract In view of the opportunity to use alkali–halide crystals with indium impurity for the registration of ionising radiation we have studied the influence of a method of impurity doping and mechanical treatment of a crystal on its sensitivity to X-ray. It is shown that the doping of a crystal with In 3+ reduces the sensitivity of medium. Optical and X-ray spectral experiments have allowed us to conclude that this phenomenon is caused by a change in the impurity centre structure. It is proved experimentally that mechanical crushing results in the transformation of the luminescent centres. This does not allow the effective conversion of the centres under synchrotron radiation.

Radiophotoluminescence of alkali-halide crystals stimulated by Bessel laser beam

Abstract A new approach to realization of optimal high-resolution reading of deep X-ray images in X-ray-sensitive materials on the base of alkali-halide crystals modified with admixtures has been suggested and investigated experimentally. A possibility to use diffraction axicons with ring aperture for forming micron bright light beams (spatially truncated Bessel beams) which can efficiently de-excite radiophotoluminescence centers lying at large depth in crystals is also presented.

Aggregation of impurity in NaCl-Ni crystals

The investigations of optical spectra at various treatments of NaCl-Ni crystals were made. It is determined that variations of the spectra may not be explained by creation of nickel clusters only. A possible reason of spectra behavior was offered.

New storage phosphor for X-ray microscopy for biological application

The new silverless radiophotoluminescence substances - a single alkaly- halide crystals (nondoped and doped by In +2 ) are proposed and tested as X-ray image detectors. Their spatial resolution is not worse than 2 pm and they allow detection of pictures in X-rays with a dynamic range of about I 0 000. A stored X-ray image can be read out many times by photoluminescence measurements under UV excitation. The image can be erased completely by heating ofphosphor at a temperature of 400 °C during a half an hour. Unique combination of the resolution and the dynamic range of lyminosity offers sample scope for x-ray microscopy under biology. Keywords: X-ray microscopy, radiophotoluminescence, alkaly- halide crystals