Quantum Chemical Reactions in the Deep Cold
Quantum Chemical Reactions in the Deep Cold
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DOI：
10.1038/scientificamerican0286-46
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发表时间：
1986-02
影响因子：
3
通讯作者：
V. Goldanskii
中科院分区：
文献类型：
--
作者：
V. Goldanskii
From our daily experience we know that chemical reactions slow down at low temperatures. Meat, for instance, can be stored by freezing, a fact that even ancient peo ples seemed to realize. About a centu ry ago the Swedish physical chemist Svante Arrhenius proposed a law of classical chemistry that relates chemi cal reaction rate to temperature. Ac cording to the Arrhenius equation, at absolute zero (zero degrees Kelvin, or minus 273 degrees Celsius) the rate of all chemical reactions must be zero, which is another way of saying that the reactions must come to a stop. Experimental evidence, however, reveals that although in general the Arrhenius equation accurately de scribes the rate of chemical reactions at relatively high temperatures, the equation fails at low temperatures. In such a domain a quantum-mechanical effect known as tunneling comes into play that allows classically forbid den chemical reactions to take place. Specifically, entire atoms can tunnel through barriers represented by the re pulsive forces of other atoms and form complex molecules even though the at oms do not have the energy required by classical chemistry to overcome the repulsion. Of course, the rate at which complex molecules can be formed is extremely low, but the tunneling proc ess could play a significant role. In this connection I have suggested the possibility of a cold prehistory of life: the formation of rather complex organic molecules in the deep cold of outer space, where temperatures usu ally reach only a few degrees Kelvin. Cosmic rays (high-energy protons and other particles) might trigger the syn thesis of such molecules in dark clouds of interstellar dust. Afterward the re actions would proceed, slowly but
