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41.
42.
I. N. Ogorodnikov V. A. Pustovarov S. I. Omel’kov A. V. Tolmachev R. P. Yavetskiĭ 《Optics and Spectroscopy》2007,102(1):60-67
The paper reports on a study of the luminescence of lithium borate crystals (Li6Gd(BO3)3 doped by Eu3+ and Ce3+ ions, Li5.7Mg0.15Gd(BO3)3: Eu, and Li6Eu(BO3)3) initiated by selective excitation by synchrotron radiation at excitation energies of 3.7–27 eV at 10 and 290 K. Efficient energy transfer between the rare-earth ions Gd3+ → Ce3+ and Gd3+ → Eu3+ was found to proceed by the resonance mechanism, as well as by electron-hole recombination. Fast decay kinetics of luminescence of the Ce3+ activator centers was studied under intracenter photoexcitation and excitation in the interband transition region. The mechanisms involved in luminescence excitation and radiative relaxation of electronic states of rare-earth ions are analyzed, and the energy transfer processes operating in these crystals are discussed. 相似文献
43.
Positron-emitting isotopes of arsenic, 70As (T
1/2 = 53 min), 71As (T
1/2 = 64 h), 72As (T
1/2 = 26 h), and 73As (T
1/2 = 17.8 d) are of interest in biomedical investigations using PET. A fast and simple method for their production using low-energy proton and deuteron reactions on enriched Ge-targets is presented. Dry distillation of GeO2 at 1105 °C during 2 hours provides a separation efficiency of more than 60%. The loss of target material is less than one per cent and the irradiated targets can be used several times. The method allows production of diagnostically useful amounts of positron-emitting arsenic isotopes using accelerators commonly available at PET-centres. 相似文献
44.
Baranov P. G. Romanov N. G. Tolmachev D. O. Babunts R. A. Namozov B. R. Kusrayev Yu. G. Sedova I. V. Sorokin S. V. Ivanov S. V. 《JETP Letters》2008,88(9):631-635
JETP Letters - The axial fine structure with strong positive zero-field splitting for Mn2+ ions in CdMnSe/ZnSe quantum dots caused by their low dimensionality was revealed. Magnetic resonance was... 相似文献
45.
46.
B. I. Shapiro L. V. Chirkova A. I. Tolmachev Yu. L. Slominskii V. A. Kuzmin 《High Energy Chemistry》2010,44(5):418-422
The block mechanism of the formation of J-aggregates from the dimers of various dyes in an aqueous solution under the action
of the multiply charged Eu+3 cation was considered for the first time. It was shown that the structure and the position of the absorption maximum of the
mixed J-aggregates are determined by the length of the dye chromophore moiety. It was concluded that the mixed J-aggregates
are of interest as nanosized optical elements with varying optical and electronic properties depending on the structure of
cyanines used. 相似文献
47.
A. I. Tolmachev 《Journal of Surface Investigation: X-ray, Synchrotron and Neutron Techniques》2011,5(2):288-290
Solution of the problem of angular dependence of sputtering yield is divided into three parts: calculation of the number of
cascade particles as a function of their path length, definition of the path length distribution of reflected particles, and
convolution of the two results obtained. The theory is valid for the case of equal ion and target atom masses (self-sputtering)
and contains two parameters: the ratio of the transport path length to the mean free path length and the parameter of inelastic
energy losses. 相似文献
48.
I. N. Ogorodnikov N. E. Poryvai I. N. Sedunova A. V. Tolmachev R. P. Yavetskiy 《Optics and Spectroscopy》2011,110(2):266-276
The luminescence and thermally stimulated recombination processes in lithium borate crystals Li6Gd(BO3)3 and Li6Gd(BO3)3:Ce have been studied. The steady-state luminescence spectra under X-ray excitation (X-ray luminescence), temperature dependences
of the intensity of steady-state X-ray luminescence (XL), and thermally stimulated luminescence (TSL) spectra of these compounds
have been investigated in the temperature range of 90–500 K. The intrinsic-luminescence 312-nm band, which is due to the 6
P
J
→ 8
S
7/2 transitions in Gd3+ matrix ions, dominates in the X-ray luminescence spectra of these crystals; in addition, there is a wide complex band at
400–420 nm, which is due to the d → f transitions in Ce3+ impurity ions. It is found that the steady-state XL intensity in these bands increases several times upon heating from 100
to 400 K. The possible mechanisms of the observed temperature dependence of the steady-state XL intensity and their correlation
with the features of electronic-excitation energy transfer in these crystals are discussed. The main complex TSL peak at 110–160
K and a number of minor peaks, whose composition and structure depend on the crystal type, have been found in all crystals
studied. The nature of the shallow traps that are responsible for TSL at temperatures below room temperature and their relation
with defects in the lithium cation sublattice are discussed. 相似文献
49.
50.