Die Häufigkeit der Edelgase Auf Der Erde Und Im Kosmos
Die Häufigkeit der Edelgase Auf Der Erde Und Im Kosmos
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埃德尔加斯的命运与宇宙
DOI：
10.1086/625673
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发表时间：
1949
期刊：
影响因子：
--
通讯作者：
H. Suess
中科院分区：
文献类型：
--
作者：
H. Suess
稀有气体的宇宙丰度现在已经足够准确，可以与地球大气的相应数据进行定量比较。似乎可以肯定地认为，宇宙中的霓虹灯丰度与天蝎座Bo星τ的霓虹灯含量接近。其他稀有气体的值是用作者先前描述的方法确定的，即通过在“平滑的”丰度曲线上对不同核物种的相对值进行内插。这些值以及霓虹值可以被认为在系数2以内是正确的。Ar-40和两个氦同位素没有被考虑，因为它们的大气浓度是放射性来源的。将这些值与地球及其大气的组成进行比较，结果表明，地球上氙气的相对丰度(氙气原子数量与硅原子数量的比率)大约是宇宙中的107倍，而霓虹灯的这个数字超过了1011。在大气层的演化过程中，明显地发生了霓氙气的分离，使浓度比改变了104倍以上。这不能用化学吸收或溶解过程来解释，但可以通过假设在有限的演化时期从地球引力场中选择性地扩散来理解。更详细地说，发现Ne、A36加上A38、Kr和Xe的地球丰度和宇宙丰度之比与原子量之比接近于一条曲线，该曲线由下列公式给出：
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Begin{Document}$$-{\mathm{log}}_{10}\frac{N_{ter}}{N_{sol}}=10\x e^{-0.045M/m_1}}+7.1，$$\end{Document}式中，Nter=地球大气中存在的稀有气体原子每100个地球中存在的Si原子；Nsol=宇宙中每100个Si原子中的稀有气体原子；M=稀有气体的原子量；以及M1=原子质量单位。这个函数的形式对应于人们期望从选择性扩散中得到的结果。对该方程的进一步讨论表明，指数的极小值使之不能解释仅仅由于高温而选择性地逃离地球引力场的现象，但只有考虑到演化时地球自转的短周期，才能理解这个小的值。方程式表明，原来存在的稀有气体中，约有107份比1可能在没有经过分离的情况下从地球物质中逃逸出来，只剩下一小部分残留气体参与了分离过程。值得注意的是，根据给出的方程，大气和宇宙稀有气体的同位素组成之间应该存在显著的差异。对从陨石、岩石或含有过量霓气的天然气中获得的Ne和Ar的同位素组成的调查，可能会导致对所提出的假设的正确性做出最终决定。
The cosmic abundance of the rare gases is now known with sufficient accuracy to allow a quantitative comparison with the corresponding data for the earth's atmosphere. It seems safe to assume that the cosmic abundance of neon is closely approximated by Unsöld's value for the neon content of the Bo star, τ Scorpii. The values for the other rare gases have been determined in a way previously described by the author, viz., by interpolation of the relative values for the different nuclear species in "smoothed" abundance curves. These values, as well as the neon value, may be considered to be correct within a factor of 2. Argon 40 and the two helium isotopes are omitted from consideration because their atmospheric concentration is of radiogenic origin. The comparison of these values with those for the composition of the earth and its atmosphere show that the relative abundance of xenon (the ratio of the number of xenon atoms to the number of silicon atoms) is about 107 times smaller on the earth than in the universe, whereas for neon this figure exceeds 1011. A separation of neon from xenon, shifting the ratio of concentrations by a factor of more than 104, has obviously taken place during the process of the atmosphere's evolution. This cannot be explained by chemical absorption or solution processes but can be understood by assuming selective diffusion from the earth's gravitational field during a limited epoch of evolution. In greater detail, it is found that the ratios of terrestrial and cosmic abundances of Ne, A36 plus A38, Kr, and Xe, plotted against atomic weight, lie close to a curve, which is given by the following equation:\documentclass{aastex}
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\begin{document}$$-{\mathrm{log}}_{10} \frac{N_{ter}}{N_{sol}} = 10 \times e^{-0.045M/m_{1}} + 7.1,$$\end{document} in which Nter = atoms of rare gas present in the earth's atmosphere per 100 atoms of Si present in the earth; Nsol = atoms of rare gas in the universe per 100 atoms of Si; M = atom weight of rare gas; and m1 = atomic mass unit. The form of this function corresponds to what one would expect to result from selective diffusion. Further discussion of the equation shows that the remarkably small value of the exponent makes it impossible to explain the selective escape from the earth's field of gravitation as a consequence of high temperature only, but that the small value can be understood only if the short period of the earth's rotation at the time of evolution is taken into account. The equation indicates that approximately 107 parts to 1 of the rare gases originally present may have escaped from terrestrial matter without undergoing separation, leaving only the small residual fraction to be involved in the separation process. Attention is drawn to the fact that, according to the given equation, a marked difference should exist between the isotopic composition of atmospheric and that of cosmic rare gases. An investigation of the isotopic composition of Ne and Ar obtained from meteorites, rocks, or natural gases containing an excessive amount of neon might lead to a final decision on the correctness of the assumption suggested.