Department of Physics, Universidad Simón Bolívar, Apartado 89000, Caracas 1080, Venezuela.
J Chem Phys. 2009 Nov 14;131(18):184704. doi: 10.1063/1.3262306.
We study the effect of coadsorption of CO and O on a Ziff-Gulari-Barshad model with CO desorption for the reaction CO + O --> CO(2) on a catalytic surface. Coadsorption of CO at a surface site already occupied by an O is introduced by an Eley-Rideal-type mechanism that occurs with probability p, 0 < or = p < or = 1. We find that besides the well-known effect of eliminating the second-order phase transition between the reactive state and an O-poisoned state, the coadsorption step has a profound effect on the transition between the reactive state and the CO-poisoned state. The coexistence curve between these two states terminates at a critical value k(c) of the desorption rate k, which now depends on p. Our Monte Carlo simulations and finite-size scaling analysis indicate that k(c) decreases with increasing values of p. For p = 1, there appears to be a sharp phase transition between the two states only for k at (or near) zero.
我们研究了在 Ziff-Gulari-Barshad 模型中 CO 和 O 共吸附对 CO 脱附的影响，该模型用于研究催化表面上的反应 CO + O --> CO(2)。通过 Eley-Rideal 型机制，在已经被 O 占据的表面位置上引入 CO 共吸附，该机制的发生概率为 p，0 < or = p < or = 1。我们发现，除了消除反应状态和 O 中毒状态之间的二阶相变的已知效应外，共吸附步骤对反应状态和 CO 中毒状态之间的转变有深远的影响。这两种状态之间的共存曲线在解吸速率 k 的临界值 k(c)处终止，现在 k 取决于 p。我们的蒙特卡罗模拟和有限尺寸标度分析表明，k(c)随 p 值的增加而减小。对于 p = 1，只有在 k 为（或接近）零时，两种状态之间似乎才会出现明显的相变。
