Control of Nonadiabatic Passage through a Conical Intersection by a Dynamic Resonance

详细信息    查看全文

• 作者：Michael Epshtein ; Yair Yifrach ; Alexander Portnov ; Ilana Bar
• 刊名：The Journal of Physical Chemistry Letters
• 出版年：2016
• 出版时间：May 5, 2016
• 年：2016
• 卷：7
• 期：9
• 页码：1717-1724
• 全文大小：372K
• 年卷期：0
• ISSN：1948-7185

文摘

Nonadiabatic processes, dominated by dynamic passage of reactive fluxes through conical intersections (CIs), are considered to be appealing means for manipulating reaction paths, particularly via initial vibrational preparation. Nevertheless, obtaining direct experimental evidence of whether specific-mode excitation affects the passage at the CI is challenging, requiring well-resolved time- or frequency-domain experiments. Here promotion of methylamine-d₂ (CH₃ND₂) molecules to spectral-resolved rovibronic states on the excited S₁ potential energy surface, coupled to sensitive D photofragment probing, allowed us to follow the N–D bond fission dynamics. The branching ratios between slow and fast D photofragments and the internal energies of the CH₃ND(X̃) photofragments confirm correlated anomalies for predissociation initiated from specific rovibronic states. These anomalies reflect the existence of a dynamic resonance that strongly depends on the energy of the initially excited rovibronic states, the evolving vibrational mode on the repulsive S₁ part during N–D bond elongation, and the manipulated passage through the CI that leads to CH₃ND radicals excited with C–N–D bending. This resonance plays an important role in the bifurcation dynamics at the CI and can be foreseen to exist in other photoinitiated processes and to control their outcome.