Time domain solution for multiple scattering and the coda envelopes

This article summarizes work on multiple scattering based on models of media with randomly distributed scatterers. The scatterers are isotropic and statistically uniform. Measuring distance in terms of mean-free pathL _s and time in terms of the mean-free timesL _s/V, whereV is the velocity of scattered waves, we have more convenient dimensionless distance and time. It can be shown that after the dimensionless time equals 0.65 energy contributed from multiple scattering becomes predominant. Thus the later coda reflects the effect of multiple scattering rather than single scattering. Treating the seismic record, including starting and tail parts, as a whole, the diffusion theory predicts that at a dense distribution of scatterers and a small distance between source and receiver, codas reflect mainly intrinsicQ _i. Of course, this conclusion is coincident with the presumption of the diffusion theory,Q _s>Q _i. However, from a new integral equation of multiple scattering, which deals with the scattered waves and primary waves separately, the conclusion is similar but clearer. This article quotes the new expression for coda energy in two-dimensional space. It shows that if the receiver is close to the source, the coda decay reflects only intrinsicQ _i, then as the distance increases, effects of scatteringQ _s, are involved in the decay feature. The theoretical plots of coda decay show that it seems in most cases in the earthQ _i should not be smaller than one tenth ofQ _s.Project Sponsored by the Joint Earthquake Science Foundation of China.     

叶蜡石、高岭石和迪开石的吸收光谱研究

对不同地区叶蜡石、高岭石、迪开石的吸收光谱测量及其高斯谱拟合说明，三各矿物的吸收光谱均由一个吸收边和三个吸收峰叠加而成。主吸收峰在562nm左右，峰高以迪开石为最大，高岭石次之，叶蜡石最低。同一地区不同颜色的叶蜡石，其主吸收峰位置随铁含量的增加向短波方向移动，相对峰高也随之增大。叶蜡石的颜色主要取决于主吸收峰的位置、高度和吸收边位置。可以认为，此吸收边为Fe^3 →O^2-荷移谱的低能拖尾部分，吸收峰则为铁离子的晶场谱带或晶场谱与Fe^2 →Fe^3 荷移的叠加。     

新疆绿柱石宝石辐照致色机制的吸收光谱研究

本文对新疆阿尔泰天然淡蓝、浅蓝宝石级绿柱石辐照前后及退火处理伴随着颜色改变的吸收光谱等进行了分析讨论,认为天然淡蓝、浅蓝色绿柱石经~(60)Co-γ辐照变成黄绿色,其原因主要归因于遂道中Fe~(2-)向Fe~(3+)的转变和八面体中Fe~(3+)和配位体O~(2-)的电荷转移。     

On the scavenging of SO2 by cloud and rain drops: IV. A wind tunnel and theoretical study of the absorption of SO2 in the ppb(v) range by water drops in the presence of H2O2

An experimental study involving the Mainz vertical wind tunnel is described where the rate of SO₂ removed from the air by freely suspended water drops was measured for SO₂ concentrations in the gas phase ranging between 50 and 500 ppb, and for various H₂O₂ concentrations in the liquid phase. In a first set of experiments, the pH inside the SO₂ absorbing drops was monitored by means of colour pH indicators added to the drops. In a second set of experiments, the amount of SO₂ scavenged by the drops was determined as sulfate by an ionchromatograph after the drops had been removed from the vertical air stream of the wind tunnel after various times of exposure to SO₂. The results of our experimental study were compared with the theoretical gas diffusion model of Walcek and Pruppacher which was reformulated for the case of SO₂ concentrations in the ppbv(v) range for which the main resistance to diffusion lies in the gas phase surrounding the drop. Excellent agreement between experiment and theory was obtained. Encouraged by this agreement, the theory was used to investigate the rate of sulfate production inside a drop as a function of pH. The sulfate production rate, which includes transport and oxidation, was compared with the production rate based on bulk equilibrium, as cited in the literature.     

春季高原东侧水平稳定层分析

本文利用稠密的探空资料,分析了春季高原东侧的水平稳定层。确定了该稳定层的范围和强度,指出了其温度、湿度和流场特征,并初步探讨了其维持机制。     

无载气氢化物发生－石英缝管捕集原子吸收光谱法测定地质试样中的铋

文章介绍石英缝管原子捕集技术在氢化物－火焰原子吸收光谱法测定Ｂｉ中的应用。采用自制的无载气氢化物发生装置，对实验条件进行了最佳化。实验结果表明，原子捕集技术的应用使氢化物－火焰原子吸收法的灵敏度提高２．２倍；方法检出限（３σ）达２．５ｎｇ；２０ｎｇ／ｍｌＢｉ的标准溶液１０次测定的ＲＳＤ为２．９％。方法用于地质标样中微量Ｂｉ的测定，结果与推荐值符合。     

Measurements of tropospheric OH concentrations: A comparison of field data with model predictions

Using long path UV absorption spectroscopy we have measured OH concentrations close to the earth's surface. The OH values observed at two locations in Germany during 1980 through 1983 range from 0.7×10⁶ to 3.2×10⁶ cm^-3. Simultaneously we measured the concentrations of O₃, H₂O, NO, NO₂, CH₄, CO, and the light non methane hydrocarbons. We also determined the photolysis rates of O₃ and NO₂. This allows calculations of OH using a zero dimensional time depdendent model. The modelled OH concentrations significantly exceed the measured values for low NO _x concentrations. It is argued that additional, so far unidentified. HO _x loss reactions must be responsible for that discrepancy.     

赤砂沸石对氮磷钾吸附与释放的研究

本文以安徽省繁昌县赤砂沸石为试验材料，以黄红壤为参照，研究了丝光沸石为主的天然沸石对ＮＨ、Ｈ＿２ＰＯ及Ｋ￣＋的吸附与释放，结果表明：赤砂沸石的吸铵量和吸磷量为黄红壤的３倍；其中易释放铵和可释放铵占总吸铵量８０％以上；易释放磷和可释放磷占７０％以上；赤砂沸石的速效钾含量为黄红壤的７倍左右，而钾位缓冲容量（ＰＢＣ￣Ｋ）则为黄红壤的３５倍左右。赤砂沸石用做肥料调理剂和土壤改良剂，将能够减少土壤中氮、磷、钾的流失，并提高肥料中养分的利用率。     

Ultraviolet absorption spectra of some Br-containing haloalkanes

The ultraviolet absorption cross sections were measured for CF₃Br, CF₂ClBr, CF₂Br-CF₂Br, CF₂Br₂, CHF₂Br, CHFBr-CF₃, CH₂Br-CF₃, CHClBr-CF₃ in the wavelength range 190–320 nm at 295 K. The photolysis is concluded to be the minor atmospheric sink for CHF₂Br, CHFBr-CF₃, CH₂Br-CF₃, CHClBr-CF₃.