Search results for " SPECT"
showing 10 items of 11464 documents
Short-range order and luminescence in amorphous silicon oxynitride
2000
Abstract Using Si 2p core-level X-ray photoelectron spectroscopy, we found that the short-range order in amorphous silicon oxynitride (a-SiOxNy) can be quantitatively described by a random bonding model. Results also show that the second and even further neighbours of the Si in the network affect the chemical shifts of the X-ray photoelectron spectra. Cathodoluminescence and photoluminescence of a-SiOxNy with different compositions are also measured. A red band with energies of 1.8–1.9 eV, a blue band with an energy of 2.7 eV and ultraviolet bands with energies of 13.1, 3.4–3.6, 4.4–4.7 and 5.4eV were observed. The 1.8–1.9 eV band is attributed to the O and N atoms with an unpaired electron…
Static and dynamic interaction betweenπanddelectrons in organic superconductorβ″-(BEDT-TTF)4[(H3O)Fe(C2O4)3]·C6H5Brstudied byC13NMR spectroscopy
2016
We present the results of $^{13}\mathrm{C}$ NMR experiments in an organic superconductor with localized Fe spins ${\ensuremath{\beta}}^{\ensuremath{''}}\ensuremath{-}{(\text{BEDT-}\mathrm{TTF})}_{4}[({\mathrm{H}}_{3}\mathrm{O})\mathrm{Fe}{({\mathrm{C}}_{2}{\mathrm{O}}_{4})}_{3}]\ifmmode\cdot\else\textperiodcentered\fi{}{\mathrm{C}}_{6}{\mathrm{H}}_{5}\mathrm{Br}$. We reveal the antiferromagnetic coupling between Fe $d$ spins and $\ensuremath{\pi}$ spins, which creates an exchange field antiparallel to the external field direction at the $\ensuremath{\pi}$ electrons. In addition to the static effects of Fe spins, we show from the nuclear spin-lattice relaxation rate measurement that the magn…
Infrared evolved gas analysis during thermal investigation of lanthanum, europium and samarium carbonates
2003
Abstract The characterisation of rare earth elements carbonates (REECs) was performed by thermal analysis (TG–DTG) combined with simultaneous infrared evolved gas analysis–Fourier transform infrared (EGA–FTIR) spectroscopy. The TG–DTG curves were obtained using the Perkin-Elmer PC series TGA-7 thermogravimetric analyser in the temperature range 25–800 °C both in dynamic air and nitrogen atmosphere. La 2 (CO 3 ) 3 · n H 2 O, Eu 2 (CO 3 ) 3 · n H 2 O and Sm 2 (CO 3 ) 3 · n H 2 O were analysed, the dehydration and decarbonation steps were investigated and the water content was calculated. The trace rare earth elements in lanthanum, europium and samarium carbonates were determined by Philips PU…
Calibration transfer in chemiluminescence analysis
2001
Abstract Direct standardization (DS) and piecewise direct standardization (PDS) methods are applied to multivariate standardization of chemiluminescence signals using PLS model as the calibration model. The linear concentration interval of the chemiluminescence determination was determined. This interval was located using univariate robust calibration by least median of squares (LMS) method. The linear calibration model was corroborated by conventional least-squares method. The standardization subset and window size were optimized by means of the prediction residual error sum of squares. Several instrumental sources of variability have been studied: the detection cell, instrument, batch ver…
Label-Free Proteomics of Quantity-Limited Samples Using Ion Mobility-Assisted Data-Independent Acquisition Mass Spectrometry
2021
Over the past two decades, unbiased data-independent acquisition (DIA) approaches have gained increasing popularity in the bottom-up proteomics field. Here, we describe an ion mobility separation enhanced DIA workflow for large-scale label-free quantitative proteomics studies where starting material is limited. We set a special focus on the single pot solid-phase-enhanced sample preparation (SP3) protocol, which is well suited for the processing of quantity-limited samples.
LiF crystals irradiated with 150MeV Kr ions: Peculiarities of color center creation and thermal annealing
2013
Abstract Color centers in LiF crystals are studied under irradiation at room temperature with 150 MeV Kr ions in the fluence (Φ) range of 1010–1014 ions/cm2 with a beam current density of 10, 50, and 100 nA/cm2, corresponding to flux of 4.46 × 109, 2.23 × 1010 and 4.46 × 1010 ions/(cm2 × s), respectively. At Φ ⩾ 3 × 1012 ions/cm2 besides F and Fn centers also charged F 3 + centers are created. Thermal annealing of irradiated LiF crystals with Φ ⩾ 1013 ions/cm2 at 400 K leads to a decrease of F centers (due to annihilation with H centers) and an enhancement of complex Fn color centers (neutral and charged) due to interaction with thermally activated anion vacancies. Annealing LiF crystals at…
φ production in annihilation at rest
1991
Abstract We report on measurements of the branching ratios for φ production in p p annihilation at rest in H 2 gas. Branching ratios for φπ 0 , φη, φϱ 0 , φω and φπ + π − are determined for two data sets with different contributions of annihilations from S and P states of the p p system. The branching ratios are compared to corresponding annihilation modes where the φ is replaced by an ω meson. We conclude that φ production is in most reactions enhanced with respect to the expectation based on the OZI rule. In annihilations from the spin triplet ground state of antiprotonic hydrogen into φπ the OZI rule is violated dramatically.
<title>Micro-Raman scattering and infrared spectra of hemoglobin</title>
2008
Confocal micro-Raman and FT-IR spectroscopies have been used for detection of radiation influence of hemoglobin of patients examined by radio-isotopes diagnosis (Tc99m). After irradiation we observed some little changes of the Raman scattering bands which connected with out of plane porphyrine bending vibrations, also we observed additional band due to methemoglobin. Radiation of blood lead to the transition from hemoglobin (Fe2+) to methemoglobin (Fe3+) with a delocalization of iron from porphyrine plane. It was shown that FT-IR spectra indicate the radiation effects on hemoglobin.© (2008) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is per…
ESR study of the liposome membrane physical parameters in the heating-cooling cycles.
1998
Abstract Changes of dynamic and structural parameters of egg yolk lecithin (EYL) liposome membranes in the heating-cooling cycles have been studied using the E S R spin probe method. The investigations were conducted in the range of temperatures from -18 °C to +60 °C. It has been found that in the range of temperatures -15 °C to +45 °C in both the heating and the cooling run the spectroscopic parameters changed practically along the same curve (reversible changes). However, after exceeding this range of temperatures one of the parameters (partition coefficient of the spin probe 2,2,6,6 -tetramethylpiperidine -1-oxyl; TEMPO) changed along a closed curve, showing the phenomenon of thermal h…
Portable Spectroscopic Techniques for the Non-invasive Identification of two historical yellow pigments: Applications and Practical Challenges
2022
Abstract Decades of technological advances in instrumental analysis have transformed many techniques from laboratory in portable analytical tools with increasing their applicability in situ to the study of cultural heritage. It is known that the painting realisation varies from artist to artist, and the identification of the pigments provides a decisive contribution to trace their authenticity and to support an appropriate restoration work. However, in some cases, due to the complexity of painting composition, it is difficult to distinguish between pigments having a similar chemical composition and colour. Here, a systematic study through combined use of portable non-invasive spectroscopic …