Ultrafast laser multihoton-gated reaction of photochromic molecules.

光致变色体系的瞬时性质变化不仅从基本化学反应过程的角度，而且从应用于可重写光学存储器和开关等光电子器件的角度，引起了人们的极大关注。最近，我们报道了一种光致变色的二芳基乙烯衍生物在稳态光照射下反应产率较低的激光诱导的环反转反应(超过50倍)。反应谱的激发强度和脉冲宽度效应表明，多光子吸收获得的较高激发态可以打开有效的光致变色反应通道。为了阐明多光子门控环逆转反应的详细机理和确认多光子门控环逆转反应的普遍性，我们在…上研究了各种二芳基乙烯衍生物的反应动力学通过纳秒、皮秒和飞秒脉冲激光激发，溶液和聚合物基质中的IVE更多。结果表明，所考察的所有二芳基乙烯衍生物都发生了皮秒激光脉冲激发的多光子回旋反应，该反应也发生在聚合物基质中。此外，用可见光的双光子能量直接激发单光子并不会导致有效的回旋。这一结果表明，由光吸收选择规则调节的特定激发态对有效反应的发生起着重要作用。除了皮秒非相干多光子激发外，我们还研究了飞秒双脉冲激发的相干多光子激发。作为这项研究的结果，我们观察到反应产率依赖于低频相干振动的相位的调制。对多光子门控光致变色反应的动力学和机理进行了全面的讨论。较少

The instant property change in photochromic systems has been attracting muuch attention not only from the viewpoint of the fundamental chemical reaction processes but also from the application to optoelectronic devices such as rewritable optical memory and switches. Recently, we reported laser-induced enhancement(more than 50 times)of cycloreversion reaction in a photochromic diarylethene derivatives with a low reaction yield under the steady-state light irradiation. The excitation intensity and pulse duration effects of the reaction profiles revealed that higher excited states attained by multiphoton absorption could open the effective photochromic reaction channel. This multiphoton-gated reaction may provide a new approach to erasable memory media with non-destructive readout capability.In order to elucidate the detailed mechanisms and to confirm the generality of the multiphoton-gated cycloreversion reaction, we have investigated the reaction dynamics of various diarylethene derivat … More ives in solutions and in polymer matrices by means of nanosecond, picosecond, and femtosecond pulsed laser excitation. From these results, it was revealed that all of the diarylethene derivatives examined here underwent the multiphoton cycloreversion by picosecond laser pulsed excitation and this reaction also took place in polymer matrices. In addition, direct one photon excitation with two-photon energy of the visible light did not lead to the efficient cycloreversion. This result indicates that the specific excited state regulated by the optical absorption selection rule takes an important role for the efficient reaction to take place.In addition to the picosecond incoherent multiphoton excitation, we have investigated the coherent multiphoton excitation by means of the femtosecond double pulse excitation. As a result of this investigation, we have observed the modulation of the reaction yield dependent on the phase of the low frequency coherent vibrations. The dynamics and mechanisms of multiphoton-gated photochromic reaction were comprehensively discussed. Less