溴、碘的半熔法-电感耦合等离子质谱(ICP-MS)测定

样品用碳酸钠和氧化锌混合熔剂半熔,用80℃～100℃水提取,用强酸型阳离子树脂分离溶液中的大量钠等阳离子,采用电感耦合等离子质谱直接测定溶液中的溴和碘。测定下限溴为0．15μg／g,碘为0．028μg／g。     

硫化物矿物中痕量元素的激光剥蚀-电感耦合等离子体质谱微区分析进展

第一行过渡金属元素及痕量贵金属元素高度富集在硫化物矿物中,常形成具有工业意义的矿床,使得硫化物具有重大的经济价值。对天然硫化物矿物中的这些痕量金属元素丰度及其分布的研究,在矿石成因学、经济地质学、环境地球化学等领域具有重要的应用价值。激光剥蚀-电感耦合等离子体质谱(LA-ICP-MS)微区分析技术是一种强大的痕量元素分析工具,非常适合直接分析硫化物矿物中痕量元素的浓度及其空间分布。由于硫化物的激光剥蚀特性与硅酸盐及氧化物不同,分析校准用的标准物质又极度缺乏,严重阻碍了这一技术在硫化物矿物微区分析中的应用。本文评述了硫化物简介、硫化物中痕量金属元素分析的意义、LA-ICP-MS微区分析技术在硫化物矿物痕量元素分析中的优势及近年来的应用进展、硫化物分析中的干扰与校准、包含铂族元素及金的硫化物标准物质的研制进展及合成硫化物标准物质最有应用前景的方法。     

ICP-MS测定甘肃某农场大气颗粒物中的铬、铜、砷、镉、铅含量

空气滤膜吸附采集甘肃某农场大气粉尘样品,采用盐酸—硝酸—氢氟酸—高氯酸溶解,电感耦合等离子体质谱法（ICP-MS）同时测定溶液中铬、铜、砷、镉、铅等重金属元素含量,分析农田环境大气颗粒中的重金属元素对农作物的影响,同时验证不同仪器工作参数对测定结果的影响。实验表明：在选定的实验条件下,分析元素的检出限低,准确性和精密度...     

From cosmic ray physics to cosmic ray astronomy: Bruno Rossi and the opening of new windows on the universe

Bruno Rossi is considered one of the fathers of modern physics, being also a pioneer in virtually every aspect of what is today called high-energy astrophysics. At the beginning of 1930s he was the pioneer of cosmic ray research in Italy, and, as one of the leading actors in the study of the nature and behavior of the cosmic radiation, he witnessed the birth of particle physics and was one of the main investigators in this fields for many years. While cosmic ray physics moved more and more towards astrophysics, Rossi continued to be one of the inspirers of this line of research. When outer space became a reality, he did not hesitate to leap into this new scientific dimension. Rossi’s intuition on the importance of exploiting new technological windows to look at the universe with new eyes, is a fundamental key to understand the profound unity which guided his scientific research path up to its culminating moments at the beginning of 1960s, when his group at MIT performed the first in situ measurements of the density, speed and direction of the solar wind at the boundary of Earth’s magnetosphere, and when he promoted the search for extra-solar sources of X rays. A visionary idea which eventually led to the breakthrough experiment which discovered Scorpius X-1 in 1962, and inaugurated X-ray astronomy.     

Particle acceleration and nonthermal radiation in space plasmas

Acceleration processes for fast particles in astrophysical and space plasmas are reviewed with emphasis on stochastic acceleration by MHD turbulence and on acceleration by shock waves. Radiation processes in astrophysical and space plasmas are reviewed with emphasis on plasma emission from the solar corona and electron cyclotron maser emission from planets and stars.     

Spectra and light curves of GRB afterglows

We performed accurate numerical calculations of angle-, time-, and frequency-dependent radiative transfer for the relativistic motion of matter in gamma-ray burst (GRB) models. Our technique for solving the transfer equation, which is based on the method of characteristics, can be applied to the motion of matter with a Lorentz factor up to 1000. The effect of synchrotron self-absorption is taken into account. We computed the spectra and light curves from electrons with a power-law energy distribution in an expanding relativistic shock and compare them with available analytic estimates. The behavior of the optical afterglows from GRB 990510 and GRB 000301c is discussed qualitatively.     

Radar Campaign to Determine the Dependence of Initial Radii of Meteor Plasma Trains on Trajectory and Orbit

Experimental and theoretical work on the transverse dimensions of meteoric plasma trains have not converged to provide generally accepted values especially uncertain is the dependence of the train radii on meteor speeds. The roles of the meteoroid structure, fragmentation and plasma processes such as ion–electron instabilities need establishing. Knowledge of the quantitative spatial distribution of plasma in meteor trains is essential for a correct interpretation of fluxes and orbital characteristics. A current project is described which employs the AMOR 26 MHz radar facility in conjunction with a frequency managed radar operating at longer wavelengths designed to measure the ionization train radii, heights, atmospheric speeds and orbits of individual meteors.     

Influence of plasma on formation of crystalline Fe2SiO4 grains

The production of Fe₂SiO₄ (fayalite) crystalline grains was performed by two processes, namely, grain formation in a plasma field by evaporating a mixture powder of Fe and SiO and heat treatment of the product collected on the radio-frequency (RF) electrode side. Fe grains <20 nm in size covered with an amorphous SiO layer selectively formed Fe₂SiO₄ grains by heating at 800 °C. By heating at 600 °C, in addition to the formation of Fe₂SiO₄ crystal grains, the FeO phase appeared. The doping effect of excited oxygen in a plasma field into the Fe small grains may be the trigger on the formation of fayalite through the FeO phase formation. The present experimental result suggests that the probability of Fe₂SiO₄ grain formation in space is low.     

New generation mechanisms for X-ray quasi-periodic oscillations in accreting neutron stars

We propose three mechanisms for the generation of quasi-periodic oscillations (QPOs) in X-ray binaries. Two of them are based on an analogy with nonlinear oscillations of gaseous cavities in a fluid. The first mechanism, called magnetocavitation, implies that X-ray QPOs are produced by radial oscillations of the neutron-star magnetosphere interacting with accreted plasma. The photon-cavitation mechanism is considered when studying X-ray QPOs in neutron stars with critical (Eddington) luminosities. In this case, X-ray QPOs are generated by radial oscillations of photon cavities in the fully ionized hydrogen plasma that settles in the accretion column of a compact object. The mechanism according to which X-ray QPOs result from nonlinear oscillations of current sheets originating in accretion disks is suggested to explain QPOs in X-ray binaries with black holes and in cataclysmic variables. The calculated values of basic physical parameters of QPOs, such as the characteristic frequency, the dependences of QPO frequency and amplitude on X-ray flux, photon energy, and QPO lag time between photons at different energies are in good agreement with observational data.     

Diffuse Baryons in Cosmic Structures

I review the processes that govern the amount and the thermal state of the hot plasma pervading clusters and groups of galaxies: the gravitational heating driven by the DM merging histories, the radiative cooling of baryons, and the energy fed back by SNe and by AGNs or quasars. I argue that the X-ray emissions and the entropy levels now observed from clusters to groups require the AGNs to contribute substantially to preheat the gas before it falls into clusters, and the quasars to blow some plasma out of groups and galaxies.