脉冲X射线剂量率测量不确定度分析

“强光一号”短脉冲高能X射线剂量率测量,主要包括脉冲射线总剂量与脉冲射线时间宽度的测量,前者采用热释光剂量计测量,后者采用PIN半导体探测器记录。根据不确定度传递数学模型,分析了影响X射线剂量和脉冲宽度测量结果的因素。针对“强光一号”短脉冲高能X射线测量,定量地给出了各种因素引入的测量不确定度,总剂量测量是影响剂量率测量准确性的决定性因素,其相对标准不确定度为25.1％,脉冲宽度测量不确定度为3.7％,剂量率测量扩展不确定度为50.8%,置信概率95%。     

Spectroscopy Study on Cobalt EDTA Complexes

The photoacoustic spectra of Co(H2EDTA)·3H20, Ca[Co(EDTA)H20]·4H20, Sr[Co(HEDTA)H20]2·4H20, Ba[Co(HEDTA)H20]2·4H20 complexes crystal are determined in the region of 300–800nm. In these spectra, the separations of absorption bands observed at 510nm and 650nm, the peak widths of 510nm band are variable in this series complexes. It is explained by the electron mutual effect, strength of ligand field and the symmetry of coordination group. The structure characters of these series complexes are also discussed.     

Assignments of Nonexchangeable Proton Resonances and the Solution Structures of d–TGGGT

In this paper, we report the studies of the solution structures of synthetic pentadeoxyribonucleotide d-TGGGT(NH₄ ⁺ salt) using 2D–NMR. The 1H–NMR experiments with different temperatures and concentrations reveal an equilibrium between single strand and aggregation. In the experimental condition(22°C, 13mmol/ L), the cross peaks in the COSY spectrum are mainly from single strand, and the spin systems of sugar resonances of this component can be assigned. In contrast, the cross peaks in the NOESY spectrum mainly come from aggregation and the sequential assignments of bases, sugar 1′, 2′ and 2″ protons can be carried out. From NOE connectivities, it is obvious that the aggregation adopts a right–handed helix conformation. It is suggested that the aggregation in our experiment corresponds to the tetramolecular complex.     

Spectroscopic Properties and Electronic Structure of Bis(L—Histidine)Copper(II) Dinitrate Dihydrate

Electronic absorption spectrum, photoacoustic absorption spectrum and ESR spectrum of bis(L-histidine)copper(II) dinitrate dihydrate crystal were recorded. The experimental results are discussed quantitatively with ligand field theory (LFT) and the radial wave function of non-free copper(II). Our calculations coincides well with the experimental results, and in particular, provides significant correlations between the spectra and coordination structures. The ESR spectrum gives some information about the restudy of classification for the ESR spectra of bis(amino acidato)copper(II) complexs. Additionally, the differences between crystal and frozen solution spectra due to the variance of PH are also reported for the title compound.     

Spectroscopic Properties and Electronic Structure of (L-Glutamato)(2, 2′-Bipyridine) copper(II)

Cu(L-glu)(bpy)(L-glu = L-glutamato; bpy = 2, 2′-bipyridine) was prepared. Its electronic absorption spectrum and photoacoustic spectrum were recorded at room temperature. They were compared with each other and compared quantitatively with ligand field theory(LFT) and the radical wave function of non-free ions^[1–3]. Therefore, the electronic structure was also investigated with its spectrum behaviors and PLFT^[1–3].     

Spectroscopic and Binding Properties of Berberine to DNA and Its Application to DNA Detection

Berberine(BER) binds to the double helical DNA with a high affinity There is only a much smaller hypochromism and no shifts in the absorption spectra when BER binds to calf thymus DNA(CT DNA) The fluorescence yields increase dramatically when BER binds to DNA, with no shifts in the emission maximum. These spectral changes are in contrast to the behavior observed with many fluorescent intercalates Groove binding rather than intercalation was suggested to be the cause of these spectral changes. Consistent with groove binding, for polyamide anion quenching studies showed that the magnitude of K_sv of the bound BER was higher than that of the free BER. The addition of salt to the solution releases the DNA-bound drug action from the groove and causes a decrease in the fluorescence yield. The results of all above studies proved the groove binding of BER to DNA. The large fluorescence enhancements observed when BER binds to DNA and the poor fluorescence yield of BER in the absence of DNA can be used for sensitive detection of DNA The linear concentration range was 0–20μg/ml The limit of detection for CT DNA was 12 ng/ml     

A Direct Experimental Evidence of Collective Electron Resonance Mechanism of Surface Enhanced Infrared Spectroscopy (Seirs)

Abstract

We report here the preliminary results of the surface enhanced transmission infrared spectra of CH₃(CH₂)₇Azo(CH₂)₃COOH monolayers on CaF₂ substrate which was coated by silver island films with different size and distribution. The larger enhancement of absorbance of v(C=O) in COOH residing between silver island gap and small enhancement of absorbance of vibration mode of COO^? located on the silver islands are observed. It give us a direct experimental evidence of the collective electron resonance mechanism of surface enhance infrared spectroscopy (SEIRS), i.e. the decrease of the electromagnetic (EM) coupling reduces the enhancement factor of SEIRS.     

Spectroscopic Characterization of Metamictization and Recrystallization in Zircon and Titanite

Recent applications of infrared and Raman spectroscopy in the study of the metamict (or "amorphized") state, high-temperature recrystallization and radiation-induced OH species in natural zircon (ZrSiO₄) and titanite (CaTiSiO₅) are reviewed.     

The β-γ phase transition in titanite and the isosymmetric analogue in malayaite

X-ray diffraction technique and hard mode infrared spectroscopy were used to study the thermal behaviour of synthetic titanite, CaTiSiO₅, two natural titanite samples and iso-structural malayaite, CaSnSiO₅. Both pure minerals show a thermal anomaly near 500 K. Specific heat measurements show an intermediate phase in synthetic titanite. Impurities in titanite tend to suppress the discontinuity near 500 K. The β-γ transition near 820 K is not affected by Fe and Al defects in the natural material. Infrared studies in malayaite show a change of the temperature dependence of the phonon frequencies. X-ray experiments show weak structural rearrangements with heating but no evidence of a symmetry breaking phase transition near 500 K The character of the 500 K anomaly in malayaite is more similar to the β-γ transition (825 K) than the α-β Mtransition (496 K) in synthetic titanite.     

Two-Frequency Brillouin Fiber Laser Based on Bragg Grating Fabry-Perot Cavity

Abstract

A novel and simple two-frequency Brillouin fiber laser is presented. It is based on a fiber Fabry-Perot cavity with fiber Bragg gratings as reflectors. The model of stimulated Brillouin scattering in fiber grating–based Fabry-Perot resonator is investigated. The laser allows conversion efficiency of close to 100% and suppresses the higher-order Stokes waves. The theoretical prediction is presented and the experimental demonstration is realized.