The High Energy X-ray telescope (HE) onboard the Insight-HXMT astronomy satellite

The Insight-Hard X-ray Modulation Telescope(Insight-HXMT) is a broadband X-ray and γ-ray(1-3000 ke V) astronomy satellite. One of its three main telescopes is the High Energy X-ray telescope(HE). The main detector plane of HE comprises 18 Na I(Tl)/Cs I(Na) phoswich detectors, where Na I(Tl) is used as the primary detector to measure ~ 20-250 ke V photons incident from the field of view(FOV) defined by collimators, and Cs I(Na) is used as the active shielding detector to Na I(Tl) by pulse shape discrimination. Additionally, Cs I(Na) is used as an omnidirectional γ-ray monitor. The HE collimators have a diverse FOV,i.e. 1.1°×5.7°(15 units), 5.7°×5.7°(2 units), and blocked(1 unit). Therefore, the combined FOV of HE is approximately5.7°×5.7°. Each HE detector has a diameter of 190 mm resulting in a total geometrical area of approximately 5100 cm2, and the energy resolution is ~15% at 60 ke V. For each recorded X-ray event by HE, the timing accuracy is less than 10 μs and the deadtime is less than 10 μs. HE is used for observing spectra and temporal variability of X-ray sources in the 20-250 ke V band either by pointing observations for known sources or scanning observations to unveil new sources. Additionally, HE is used for monitoring the γ-ray burst in 0.2-3 Me V band. This paper not only presents the design and performance of HE instruments but also reports results of the on-ground calibration experiments.     

Preparation and photoelectrochemical performance of TiO<Subscript>2</Subscript>/Ag<Subscript>2</Subscript>Se interface composite film

Coupling TiO₂ with a narrow band gap semiconductor acting as the photosensitizer has attracted much attention in solar energy exploitation. In this work, the porous TiO₂ film was first formed on the conducting glass plate (CGP) substrate by the decomposition of polyethylene glycol (PEG) mixing in titanium hydroxide sol at 450°C. Then, the TiO₂/Ag²Se interface composite film was fabricated by interface reaction of AgNO₃ with NaSeSO₃ on the activated surface of porous TiO₂ film. The results of SEM and XRD analyses indicated that the porous TiO₂ layer was made up of the anatase crystal, and the Ag₂Se layer was made up of congregative small particles that have low-temperature α-phase structure. Due to its efficient charge separation for the photo-induced electron-hole pairs, the TiO₂/Ag₂Se interface composite film as-prepared has good photovoltaic property and high photocurrent response for visible light, which have been confirmed by the photoelectrochemical measurements.     

Synthesis of two carbazole-based dyes and application of two-photon initiating polymerization

Two carbazole-based polymerization initiators possessing blue fluorescence emission have been synthesized via Wittig reaction in the solid phase at room temperature. Two-photon excited fluorescence (TPEF) spectra for them were investigated under 800 nm fs laser pulse and two-photon absorption cross sections were determined by the Z-scan technique. Then two-photon initiating polymerization (TPIP) microfabrication experiments were successfully carried out. Three-dimensional lattice and artificial defects were gained, indicating that they were viable candidates for the two-photon polymerization initiator in practical application of microfabrication. Supported by the National Natural Science Foundation of China (Grant Nos. 50532030, 20771001 & 50703001), and Team for Scientific Innovation of Anhui Province (Grant No. 2006KJ007TD)     

A new series of two-photon polymerization initiators: Synthesis and nonlinear optical properties

Four photopolymerization initiators with D-π-D (D, donor; π, conjugation system) structure have been synthesized by solvent-free reaction and characterized by ¹H NMR spectroscopy, IR and elemental analysis. The one-photon and two-photon excited fluorescence have been investigated in different solvents. Experimental results of the one-photon and two-photon absorption cross sections show different trends in OPA and TPA ability with different substitution groups in donor units.     

Metal complexes of a novel bis-β-diketone-type ligand and its copper(II) complexes of two-photon biological imaging

A curcumin derivative ligand,1,7-bis(3-methoxyl-4-acetoxyl)phenyl-1,6-heptadiene-3,5-diketone (diacetylcurcumin,abbreviated as HL),and its Cu and Ni complexes have been synthesized and fully characterized by elemental analyses,IR,1 HNMR and molar conductivity.The resulting complexes exhibit two-photon excited fluorescence (TPEF) in DMF,and have been proven to be potentially useful for two-photon microscopy imaging in living cells.In addition,cytotoxicity tests showed that the low-micromolar concentrations of ML 2 did not cause significant reduction in cell viability over a period of at least 24 h and should be safe for further biological studies.     

The flux modulation of INTEGRAL

We have analyzed International Gamma-Ray Astrophysics Laboratory (INTEGRAL) data corresponding to observations of the high mass X-ray binary (HMXB) V0332+53 during its huge outburst which occurred in 2004–2005, and found that there is a quasi periodic signal with ultra low frequency of roughly 4−5×10⁻⁵ Hz in the observation. This feature is revealed through a series of consistent analyses of imagings and fittings of the energy spectrum for each science window (SCW), and shows up in the corresponding light curves. The analysis of the power spectrum also provides a hint of a power peak located around 4×10⁻⁵ Hz, after subtracting off the linear trend of the light curve, and shows the consistency with the previous analyses. A similar feature shows up in our analysis of the light curve of Crab in hexagonal dithering mode. Therefore, an instrumental effect on the flux modulation might exist in the INTEGRAL data product of different levels: imaging, spectral fitting and light curve analysis, at least for the observational mode of hexagonal dithering. Such an effect is, to our knowledge, not yet available in the current literature.

     

Multi-carbazole derivatives for two-photon absorption data storage: Synthesis, optical properties and theoretical calculation

Two novel quadrupolar organic compounds, 3-(4-((E)-2-(9-butyl-9H-carbazol-6-yl) vinyl)styryl)-9-propyl-9H-carbazole (BCSPC) and 3-(3-(3-((1E)-2-(4-((E)-2-(3-(3,5-bis(9-butyl-9H-carbazol-6-yl)phenyl)-9-butyl-9H-carbazol-6-yl)vinyl)phenyl) vinyl)-9-butyl-9H-carbazol-6-yl)-5-(9-butyl-9H-carbazol-6-yl)phenyl)-9-butyl-9H-carbazole (BCPBC), with different conjugated arms, have been designed and synthesized. Their one- and two-photon absorption (TPA) and excited fluorescence properties have been experimentally investigated. The two-photon absorption cross-sections of two compounds were estimated by two-photon excited fluorescence technique using 200 fs, 76 MHz, Ti:sapphire laser, which are 22 and 154 GM for BCSPC and BCPBC, respectively. The optimal excitation wavelengths are 780 nm for both BCSPC and BCPBC. A data recording experiment proved the potential application of the materials.     

Prelude

This year we celebrate the 85th anniversary of the Institute of Physics,Chinese Academy of Sciences(CAS).As an academic institution,the publication of a special issue dedicated to demonstrating the range and depth of researches it covers in the past     

Synthesis, photophysical properties and TD-DFT calculation of four two-photon absorbing triphenylamine derivatives

In this study,linear absorption,single-photon excited fluorescence,fluorescence quantum yields,fluorescence lifetime and two-photon excited fluorescence of a series of triphenylamine derivatives (L1,L2,L3 and L4) have been measured.L1 and L3 are D--A type dyes,while L2 and L4 are D--D--A type dyes (D=donor,A=acceptor).The investigated compounds consist of triphenylamine-bearing donor-substituted and/or systematically extended-conjugated length,which are designed to gain insight into the effect of the ethoxyl unit and-linkage length on the linear and nonlinear optical properties.The influence of solvent polarity on the photophysical properties was investigated.Employing time-dependent density functional theory (TD-DFT) calculations,the structure-property relationships are discussed.