Mode selectivity is a well-established concept in chemical dynamics. A polyatomic molecule possesses multiple vibrational modes and the mechanical couplings between them can result in complicated anharmonic motions that defy a simple oscillatory description. A prototypical example of this is Fermi-coupled vibration, in which an energy-split eigenstate executes coherent nuclear motion that is comprised of the constituent normal modes with distinctive phases. Will this vibrational phase affect chemical reactivity? How can this phase effect be disentangled from more classical amplitude effects? Here, to address these questions, we study the reaction of Cl with a pair of Fermi states of CH₃D(v₁-I and v₁-II). We find that the reactivity ratio of (v₁-I)/(v₁-II) in forming the CH₂D(v = 0) + HCl(v) products deviates significantly from that permitted by the conventional reactivity-borrowing framework. Based on a proposed metric, this discrepancy can only be explained when the scattering interferences mediated by the CH₃D vibrational phases are explicitly considered, which expands the concept of vibrational control of chemical reactivity into the quantum regime.

模式选择性是化学动力学中一个成熟的概念。多原子分子具有多种振动模式，它们之间的机械耦合会导致复杂的非谐运动，而这些运动无法简单的振荡描述。一个典型的例子是费米耦合振动，其中能量分裂本征态执行相干核运动，该运动由具有不同相位的组成正常模式组成。这个振动阶段会影响化学反应吗？这种相位效应如何与更经典的幅度效应分开？_{在这里，为了解决这些问题，我们研究了 Cl 与 CH 3} D的一对费米态( v ₁ -I 和v ₁-II)。我们发现( v ₁ -I)/( v ₁ -II) 在形成CH ₂ D( v  = 0) + HCl( v ) 产物中的反应性比明显偏离传统反应性借用框架所允许的。_{基于所提出的度量，只有当明确考虑由 CH 3} D 振动相介导的散射干扰时，才能解释这种差异，这将化学反应性的振动控制概念扩展到量子状态。