Beryllium coating of the iron foil is made by means of magnetron sputtering. Mössbauer studies are performed by means of two registration techniques: conversion electron Mössbauer spectroscopy (CEMS) and the γ-ray technique in absorption geometry. Performed investigations confirm the original thermodynamic approach to creation of thermally stable multi-layer materials.
In this study, 57Fe Mössbauer spectroscopy has been applied to sediments collected from Qinghai Lake in Qinghai Province, China, to investigate the vertical distribution of iron species. Their Mössbauer spectra consisted of four doublets ascribable to one paramagnetic high-spin Fe3+, two paramagnetic high-spin Fe2+ with different quadrupole splittings, and one diamagnetic low-spin Fe2+ that corresponds to pyrite (FeS2). The distribution of pyrite suggested climatic changes during the past nine thousand years. It was demonstrated that the iron speciation in the salt lake sediments by Mössbauer spectroscopy can be used to reconstruct the past environment.
Optical properties of an ultraviolet-absorbing substance (UVAS) extracted from the marine red alga, Porphyra yezoensis, have been investigated. The substance is excited by UV light, and the emitted fluorescence is detected using an intelligent fluorescence detector. The fluorescence of UVAS is weaker by four orders of magnitude than the fluorescence intensity emitted by anthracene in the same optical system. The absorbed energy is apparently not transferred to the photosynthesis process and is believed to be consumed as heat. Using photothermal spectroscopy, a signal is observed indicating that the absorbed photon energy has transferred to the heat. The waveform of the photothermal signal of UVAS is similar to that of quinoxaline, whose fluorescence quantum yield is known to be zero. It is determined that the fluorescence quantum yield and the energy of the triplet state of UVAS are 1.7 ± 0.7 ± 10−4 and 21000 ± 1000 cm −1, respectively. The conclusion is that the excited molecules of UVAS decay by passing through the triplet state and dissipate all absorbed energy as heat. 相似文献
The corrosion reaction of four Fe–Mn–Al alloys exposed to a cycling, dry–humid, SO2 (0.001% by volume) polluted atmosphere was studied. ICEMS, XPS, AES-SAM and transmission Mössbauer spectroscopy at different temperatures were employed to characterize the corrosion products. The analytical results indicate that (i) ferrihydrite is the main component of the rust; (ii) there is an abundant presence of Mn2+ and SO32–/SO42– on the top of the corrosion layer, the concentration of SO42– increasing with the number of cycles; and (iii) the magnetic hyperfine pattern exhibited by the series of low-temperature spectra of the rust is quite different from that observed in the rust formed under similar corrosive environments on iron and weathering steel. This latter finding is correlated with a slow rate of transformation of the Fe3+ species formed at the early stages of corrosion into -FeOOH, the usual final product of this type of corrosion processes. The sulphate anions, abundant inside the electrolyte during the wet periods, could be incorporated to the ferrihydrite structure being responsible for the Mössbauer spectral pattern recorded from the corrosion products at low temperatures. 相似文献
We propose a two-lattice method for direct determination of the recoilless fraction using a single room-temperature transmission Mössbauer measurement. The method is first demonstrated for the case of iron and metallic glass two-foil system and is next generalized for the case of physical mixtures of two powders. We further apply this method to determine the recoilless fraction of hematite and magnetite particles. Finally, we provide direct measurement of the recoilless fraction in nanohematite and nanomagnetite with an average particle size of 19nm. A list of values obtained for the recoilless fraction in various materials using the two-lattice method is given. 相似文献
Interaction of a semiconductor laser with its self-radiation quasielastically scattered in the environment is considered. It is established that at small coefficients of coupling of the laser with the scattering medium the spectral density of the power of an optoelectronic signal in the laser faithfully reproduces the shape of the scattered-radiation spectrum at the Doppler-shift frequencies. This makes it possible to measure the spectrum with a resolution characteristic for optical homodynation by recording the optoelectronic signal. 相似文献