介绍了Kirk—Othmer Encyclopedia of Chemical Technology（化工技术百科全书）（第五版）电子图书网络版数据库，并对该数据库使用方法和检索途径作出了说明，且结合实例简单地介绍了该数据库的检索方法。

Kirk-Othmer Encyclopedia of Chemical Technology数据库介绍及实例

(1976). Nuclear Tracks in Solids (Principles and Applications) Nuclear Technology: Vol. 30, No. 1, pp. 91-92.

Nuclear Tracks in Solids (Principles and Applications)

TiO2 nanocrystals with tunable bulk/surface defects were synthesized and characterized with TEM, XRD, BET, positron annihilation, and photocurrent measurements. The effect of defects on photocatalytic activity was studied. It was found for the first time that decreasing the relative concentration ratio of bulk defects to surface defects in TiO2 nanocrystals could significantly improve the separation efficiency of photogenerated electrons and holes, thus significantly enhancing the photocatalytic efficiency.

Tuning the relative concentration ratio of bulk defects to surface defects in TiO2 nanocrystals leads to high photocatalytic efficiency.

The sole effect of surface/bulk defects of TiO2 samples on their photocatalytic activity was investigated. Nano-sized anatase and rutile TiO2 were prepared by hydrothermal method and their surface/bulk defects were adjusted simply by calcination at different temperatures, i.e. 400–700 °C. High temperature calcinations induced the growth of crystalline sizes and a decrease in the surface areas, while the crystalline phase and the exposed facets were kept unchanged during calcination, as indicated by the characterization results from XRD, Raman, nitrogen adsorption–desorption, TEM and UV-Vis spectra. The existence of surface/bulk defects in calcined TiO2 samples was confirmed by photoluminescence and XPS spectra, and the surface/bulk defect ratio was quantitatively analyzed according to positron annihilation results. The photocatalytic activity of calcined TiO2 samples was evaluated in the photocatalytic reforming of methanol and the photocatalytic oxidation of α-phenethyl alcohol. Based on the characterization and catalytic results, a direct correlation between the surface specific photocatalytic activity and the surface/bulk defect density ratio could be drawn for both anatase TiO2 and rutile TiO2. The surface defects of TiO2, i.e. oxygen vacancy clusters, could promote the separation of electron–hole pairs under irradiation, and therefore, enhance the activity during photocatalytic reaction.

Understanding the effect of surface/bulk defects on the photocatalytic activity of TiO2: anatase versus rutile.

This paper introduces a novel method for characterizing the oxygen vacancy associates in hydrogenation-modified TiO2 by using a positron annihilation lifetime spectroscopy (PALS). It was found that a huge number of small neutral Ti3+–oxygen vacancy associates, some larger size vacancy clusters, and a few voids of vacancy associates were introduced into hydrogenated TiO2. The defects blurred the atomic lattice high-resolution transmission electron microscopy (HRTEM) images and brought about the emergence of new Raman vibration. X-ray photoelectron spectroscopy (XPS) measurement indicated that the concentration of oxygen vacancies was 3% in the TiO2 lattice. The photoluminescence (PL) spectroscopy, photocurrent, and degradation of methylene blue indicated that the oxygen vacancy associates introduced by hydrogenation retarded the charge recombination and therefore improved the photocatalytic activity remarkably.

Characterization of Oxygen Vacancy Associates within Hydrogenated TiO2: A Positron Annihilation Study

Effects of gamma irradiation at different doses up to 135 kGy on polyethylene terephthalate (PET) polymer films have been investigated by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, and ultraviolet-visible (UV-VIS) spectroscopy. From XRD analysis, it was found that even at a high dose of gamma irradiation of 135 kGy, crystallinity of the PET samples remain unchanged. However, the FTIR peak at 871 cm−1 (depicting C–H bending mode of out-of-plane vibration) and another at 1303 cm−1 (representing C–H bending mode of in-plane vibration) disappear for gamma-irradiated PET. In this study, it has also been found that γ-irradiation in air enhances the optical absorption in the wavelength region 320–370 nm. This has been attributed to free radicals being produced in the polymer by the γ-radiation. Further, the free radicals react with oxygen of air to form carbonyl group and hydroxyls. With increasing γ-dose, there is a red shift of the UV—near visible cutoff for PET. XRD and FTIR observations on γ-damage have been correlated.

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Structural and Optical Investigations of Radiation Damage in Transparent PET Polymer Films

The present measurement of positron annihilation lifetimes for the high-${T}_{c}$ superconductor $({\mathrm{Bi}}_{0.92}{\mathrm{Pb}}_{0.17}{)}_{2}{\mathrm{Sr}}_{1.91}{\mathrm{Ca}}_{2.03}{\mathrm{Cu}}_{3.06}{\mathrm{O}}_{10+\ensuremath{\delta}}$ or (Bi,Pb)-2223, as a function of temperature, has been inspired by our recent DBPARL (Doppler-broadened positron annihilation radiation line shape) finding of a step and minima in the region around ${T}_{c}(R=0)=104$ K, in the variation with temperature, of the fraction of low momentum electrons at the annihilation sites. The positron annihilation lifetime in the superconductor probes the number density of electrons at the annihilation sites. The present work observes a reduction of lifetime components in the ${T}_{c}$ region. Significant changes in the lifetime components in other temperature regions have also been observed and discussed.

Probing ( Bi 0.92 Pb 0.17 ) 2 Sr 1.91 Ca 2.03 Cu 3.06 O 1 0 + δ superconductors from 30 to 300 K by positron-lifetime measurements

PEO(1 −  x ) NH 4 ClO 4 ( x ) samples with x  = 0.18 are irradiated with gamma doses varying up to 50 kGy. DSC and XRD studies indicate, in general, a decrease in crystallinity with dose. Measurement of viscosity of aqueous solutions of the irradiated samples at the same concentration, shows that there is overall chain scission on irradiation, though there is evidence of some cross-linking also at higher doses. This is corroborated by FTIR measurements. The ion-conductivity shows a strong increase for irradiation dose 35 kGy. This suggests that there is a possibility of improving polymer electrolyte properties on gamma irradiation.

Effect of gamma irradiation on a polymer electrolyte: Variation in crystallinity, viscosity and ion-conductivity with dose

Polyether sulphone (PES) foils were irradiated under vacuum with 70 MeV C 5+ ions to the fluences of 9.3 × 10 11 , 9.3 × 10 12 and 1.2 × 10 13  ions cm −2 . Ion induced optical, chemical and structural modifications were studied by ultraviolet, visible (UV–Vis) and Fourier transform infrared (FTIR) spectroscopy and X-ray diffractometer. PES suffers degradation under irradiation, UV–Vis data show the increase of optical absorbance and the shift of absorption edge from the UV towards visible with the increase of the fluences, attributing to the formation of conjugated system of bonds. The intensity of the infrared bands, characteristics of different chemical functional groups is found to decrease with swift heavy ion (SHI) irradiation. Significant loss of crystallinity was observed at higher fluences.

Physical and chemical response of 70 MeV carbon ion irradiated polyether sulphone polymer

Swift heavy ions interact predominantly through inelastic scattering while traversing any polymeric medium and produce excited/ionized atoms. This results into the modification of physical and chemical response of the polymer. CR-39 (DOP) and polyamide nylon-6 polymer samples were irradiated with 70 MeV C 5+ ion beam to the fluences of 10 11 , 10 12 and 10 13 ions cm −2 . Modifications due to irradiation were studied using Fourier transform infra red (FTIR) spectroscopic and X-ray diffraction (XRD) technique. Considerable deformation has been observed in both the polymers at the fluence of 10 12 and 10 13 ions cm −2 . XRD analyses show slight shift of peak position and significant changes in peak width and intensity. Particle size or grain size, calculated by applying Scherrer formula, indicates measurable changes in particle size in the irradiated samples. XRD peaks at d -values of 4.335 A and 3.838 A for the virgin polyamide nylon-6 gradually change with increasing fluence into one broad peak. Some difference in the irradiation effect in these two different polymers has been observed.

Udayan De

Papers

Structural and Optical Investigations of Radiation Damage in Transparent PET Polymer Films

Probing ( Bi 0.92 Pb 0.17 ) 2 Sr 1.91 Ca 2.03 Cu 3.06 O 1 0 + δ superconductors from 30 to 300 K by positron-lifetime measurements

Effect of gamma irradiation on a polymer electrolyte: Variation in crystallinity, viscosity and ion-conductivity with dose

Physical and chemical response of 70 MeV carbon ion irradiated polyether sulphone polymer

Ion beam modification of CR-39 (DOP) and polyamide nylon-6 polymers