まとめ
南アフリカのダイヤモンドには,ヘリウム-3/ヘリウム-4の比率が含まれています. いくつかのダイヤモンドは,非常に高い比率を示しており,地球が形成されて以来ほとんど進化していない原始的なヘリウムを示唆しています.
科学分野:
- 地質化学 地質化学
- イソトープ分析とは
- 地球科学 地球科学
背景:
- ヘリウムイソトープ (ヘリウム-3/ヘリウム-4) は,惑星の進化についての洞察を提供します.
- ヘリウムの起源を理解することは,地球と太陽系科学にとって極めて重要です.
研究 の 目的:
- 南アフリカのダイヤモンドのヘリウム-3/ヘリウム-4同位体比を分析するために.
- 地球の原始的なヘリウム含有量に対する観測された比率の影響を調査する.
主な方法:
- ヘリウム-3からヘリウム-4の同位体比率分析
- 南アフリカの鉱山から13個のダイヤモンド石を採取した.
主要な成果:
- ヘリウム-3/ヘリウム-4の比率は,<10(-7) から (3.2 ± 0.25) x 10(-4) まで,著しく変化した.
- 観測された最も高い比率は,隕石で見られる原始比率を超えています.
- 最も高い比率は,太陽光型ヘリウム比率に匹敵する.
結論:
- ダイヤモンドの非常に高いヘリウム-3/ヘリウム-4比は,原始的なヘリウムの存在を示唆する可能性があります.
- これらの発見は,地球形成以来,ヘリウム-4 (放射性) の進化が最小限であることを示唆しています.
- ダイヤモンドは,地球の初期の同位体組成を研究するための貴重なサンプルとして役立つ.
関連する概念動画
Noble Gases
The elements in group 18 are noble gases (helium, neon, argon, krypton, xenon, and radon). They earned the name “noble” because they were assumed to be nonreactive since they have filled valence shells. In 1962, Dr. Neil Bartlett at the University of British Columbia proved this assumption to be false.
Nuclear Binding Energy
The difference between the calculated and experimentally measured masses is known as the mass defect of the atom. In the case of helium-4, the mass defect indicates a “loss” in mass of 4.0331 amu – 4.0026 amu = 0.0305 amu. The loss in mass accompanying the formation of an atom from protons, neutrons, and electrons is due to the conversion of that mass into energy that is evolved as the atom forms. The nuclear binding energy is the energy produced when the atoms’ nucleons are bound together;...
¹H NMR of Labile Protons: Deuterium (²H) Substitution
This lesson illustrates the role of deuterium substitution in simplifying the NMR spectrum of compounds comprising labile protons. One method employed is the use of deuterium. Amongst the three isotopes of hydrogen, deuterium (2H) has a nucleus composed of one proton and one neutron. When the D2O solvent is added to a pure dry ethanol solution, its labile proton is substituted with deuterium.
Heat Capacities of an Ideal Gas III
The number of independent ways a gas molecule can move along straight line, rotate, and vibrate is called its degrees of freedom. Supposing d represents the number of degrees of freedom of an ideal gas, the molar heat capacity at constant volume of an ideal gas in terms of d is
Nuclear Fusion
The process of converting very light nuclei into heavier nuclei is also accompanied by the conversion of mass into large amounts of energy, a process called fusion. The principal source of energy in the sun is a net fusion reaction in which four hydrogen nuclei fuse and ultimately produce one helium nucleus and two positrons.
A helium nucleus has a mass that is 0.7% less than that of four hydrogen nuclei; this lost mass is converted into energy during the fusion. This reaction produces about...
A helium nucleus has a mass that is 0.7% less than that of four hydrogen nuclei; this lost mass is converted into energy during the fusion. This reaction produces about...
Molecular Orbital Theory II
Molecular Orbital Energy Diagrams


