“metastable state”的概念、定义、翻译、参考文献-科学参考

metastable state

Physics

A condition of a system in which it has a precarious stability that can easily be disturbed. It is unlike a state of stable equilibrium in that a minor disturbance will cause a system in a metastable state to fall to a lower energy level. A book lying on a table is in a state of stable equilibrium; a thin book standing on edge is in metastable equilibrium. Supercooled water is also in a metastable state. It is liquid below 0°C; a grain of dust or ice introduced into it will cause it to freeze. An excited state of an atom or nucleus that has an appreciable lifetime is also metastable.

Astronomy

An excited energy level in an atom, ion, or molecule, from which transitions to lower energy levels are said to be forbidden. A forbidden transition is one of such low probability that it is not observed under laboratory conditions. However, in the low-density conditions of interstellar space and nebulae, electrons cannot escape from the metastable state by upward excitation to a higher level by collisions. The metastable state can then become highly overpopulated, and emission lines from the forbidden transitions can be the strongest lines in the spectrum of a nebula. See Forbidden Line.

Chemistry

A condition of a system in which it has a precarious stability that can easily be disturbed. It is unlike a state of stable equilibrium in that a minor disturbance will cause a system in a metastable state to fall to a lower energy level. A book lying on a table is in a state of stable equilibrium; a thin book standing on edge is in metastable equilibrium. Supercooled water is also in a metastable state. It is liquid below 0°C; a grain of dust or ice introduced into it will cause it to freeze. An excited state of an atom or nucleus that has an appreciable lifetime is also metastable.

单词	metastable state
释义	metastable state Physics A condition of a system in which it has a precarious stability that can easily be disturbed. It is unlike a state of stable equilibrium in that a minor disturbance will cause a system in a metastable state to fall to a lower energy level. A book lying on a table is in a state of stable equilibrium; a thin book standing on edge is in metastable equilibrium. Supercooled water is also in a metastable state. It is liquid below 0°C; a grain of dust or ice introduced into it will cause it to freeze. An excited state of an atom or nucleus that has an appreciable lifetime is also metastable. Astronomy An excited energy level in an atom, ion, or molecule, from which transitions to lower energy levels are said to be forbidden. A forbidden transition is one of such low probability that it is not observed under laboratory conditions. However, in the low-density conditions of interstellar space and nebulae, electrons cannot escape from the metastable state by upward excitation to a higher level by collisions. The metastable state can then become highly overpopulated, and emission lines from the forbidden transitions can be the strongest lines in the spectrum of a nebula. See Forbidden Line. Chemistry A condition of a system in which it has a precarious stability that can easily be disturbed. It is unlike a state of stable equilibrium in that a minor disturbance will cause a system in a metastable state to fall to a lower energy level. A book lying on a table is in a state of stable equilibrium; a thin book standing on edge is in metastable equilibrium. Supercooled water is also in a metastable state. It is liquid below 0°C; a grain of dust or ice introduced into it will cause it to freeze. An excited state of an atom or nucleus that has an appreciable lifetime is also metastable.
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