Direct mapping of curve-crossing dynamics in IBr by attosecond transient absorption spectroscopy
Direct mapping of curve-crossing dynamics in IBr by attosecond transient absorption spectroscopy
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DOI：
10.1126/science.aax0076
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发表时间：
2019-07-05
期刊：
影响因子：
56.9
通讯作者：
Leone, Stephen R.
中科院分区：
文献类型：
--
作者：
Kobayashi, Yuki;Chang, Kristina F.;Leone, Stephen R.
光激发分子的电子特性在避开的交叉点和圆锥形交叉点处会发生突变。在这里，我们报告直接映射的原型分子，一溴化碘（IBr），通过使用阿秒瞬态吸收光谱的电子和原子核之间的耦合相互作用。几个飞秒可见光脉冲共振激发IBr的（B3 P0（+）），Y（0（+））和Z（0（+））状态，和光解离动力学跟踪与阿秒极紫外脉冲，同时探测I-4d和Br-3d芯能级吸收边。与量子力学模拟的直接比较明确地确定了与绝热和非绝热通道在B/Y避免交叉和并发的双光子解离过程，涉及Y/Z避免交叉的吸收功能。结果表明，在避免交叉快速切换的价电子字符的明确证据。
The electronic character of photoexcited molecules can abruptly change at avoided crossings and conical intersections. Here, we report direct mapping of the coupled interplay between electrons and nuclei in a prototype molecule, iodine monobromide (IBr), by using attosecond transient absorption spectroscopy. A few-femtosecond visible pulse resonantly excites the (B3P0(+)), Y(0(+)), and Z(0(+)) states of IBr, and the photodissociation dynamics are tracked with an attosecond extreme-ultraviolet pulse that simultaneously probes the I-4d and Br-3d core-level absorption edges. Direct comparison with quantum mechanical simulations unambiguously identifies the absorption features associated with adiabatic and diabatic channels at the B/Y avoided crossing and concurrent two-photon dissociation processes that involve the Y/Z avoided crossing. The results show clear evidence for rapid switching of valence-electronic character at the avoided crossing.