The atomic motions that make up phonons and molecular vibrations in molecular crystals influence their photophysical and electronic properties, including polaron formation, carrier mobility, and phase transitions. Discriminating between spectator and driving motions is a significant challenge hindering optimization. Unlocking this information and developing fine-tuned controls over actively participating phonon modes would not only lead to a stronger understanding of photochemistry but also provide a significant new tool in controlling solid state chemistry. We present a strategy using rationally designed double pulses to unveil the unique function of specific excited state phonon modes. Using ultrafast spectroscopy, we identified 50 and 90 cm^–1 phonons involved in modulating the photoinduced spin-Peierls melting of potassium tetracyanoquinodimethane crystals. We show that the 50 cm^–1 phonon specifically corresponds to the coherent nuclear wavepacket involved in the charge transfer component of the overall spin-Peierls phase melting process, while the 90 cm^–1 phonon facilitates the phase transition component.

中文翻译：

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在分子晶体的光诱导相变过程中揭示相干声子的功能作用。

组成声子的原子运动和分子晶体中的分子振动会影响其光物理和电子特性，包括极化子形成，载流子迁移率和相变。区分观众和驾驶动作是阻碍优化的重大挑战。解锁这些信息并开发对主动参与的声子模式的微调控制，不仅会导致对光化学的更深入了解，而且还将为控制固态化学提供重要的新工具。我们提出了使用合理设计的双脉冲来揭示特定激发态声子模式的独特功能的策略。使用超快光谱，我们确定了50和90 cm ^–1声子参与调节四氰基喹二甲酸钾晶体的光诱导自旋-Peierls熔化。我们表明，50 cm ^–1声子特别对应于涉及整个自旋Peierls相融过程的电荷转移成分的相干核波包，而90 cm ^–1声子则促进了相变成分。