Rábai Gyula, Szántó Tibor G, Kovács Klára
Institute of Physical Chemistry, University of Debrecen, P.O. Box 7, H-4010 Debrecen, Hungary.
J Phys Chem A. 2008 Nov 27;112(47):12007-10. doi: 10.1021/jp805509b.
Low-frequency, high-amplitude pH-oscillations observed experimentally in the H2O2-HSO3(-)-S2O3(-) flow reaction system at 21.0 degrees C undergo period-doubling cascades to chemical chaos upon decreasing the temperature to 19.0 degrees C in small steps. Period-4 oscillations are observed at 20.0 degrees C and can be calculated on the basis of a simple model. A reverse transition from chaos to high-frequency limit cycle oscillations is also observable in the reaction system upon decreasing further the temperature step by step to 15.0 degrees C. Period-2 oscillations are measured at 18.0 degrees C. Such a temperature-change-induced transition between periodic and chaotic oscillatory states can be understood by taking into account the different effects of temperature on the rates of composite reactions in the oscillatory system. Small differences in the activation energies of the composite reactions are responsible for the observed transitions. Temperature-change-induced period doubling is suggested as a simple tool for determining whether an experimentally observed random behavior in chemical systems is of deterministic origin or due to experimental noise.
在21.0摄氏度的H2O2 - HSO3(-)-S2O3(-)流动反应体系中实验观察到的低频、高振幅pH振荡，在以小步长将温度降至19.0摄氏度时会经历倍周期级联到化学混沌状态。在20.0摄氏度时观察到了周期为4的振荡，并且可以基于一个简单模型进行计算。在反应体系中，当进一步逐步将温度降至15.0摄氏度时，还可观察到从混沌到高频极限环振荡的反向转变。在18.0摄氏度时测量到了周期为2的振荡。考虑到温度对振荡体系中复合反应速率的不同影响，就可以理解这种由温度变化引起的周期性和混沌振荡状态之间的转变。复合反应活化能的微小差异是导致观察到的转变的原因。温度变化引起的倍周期被认为是一种简单工具，用于确定在化学体系中实验观察到的随机行为是源于确定性还是由于实验噪声。
