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大多数光化学反应的主要过程可以归结为:分子在光辐照下由基态变为电子激发态,随即发生分子核骨架的变化(如分子的重排或键的断裂等),从而生成预期的反应产物。如果辐照光的频率仅与分子振动能级的跃迁所需能量相匹配,引起的将是分子的振动激发。在大多数情况下,受激分子仍属于电子基态,不会发生光化学反应。可是当辐照光的能密度很大时,则有可能迫使分子同时或者连续地吸收多个光子,提升到高振动激发态,并有可能导致分子从电子基态跃迁到电子激发态,从而发生键的断裂或核骨架的重排。这种光化学反应在70年代曾被称为红外光化学反应,现在则更多地被称作振动光化学反应。这个领域由于大功率红外激光器的出现和有可能实现键的选择性激发,曾引起化学界的极大关注。
Most of the photochemical reactions can be summarized as the main process: molecules under the light irradiation from the ground state into the electronically excited state, followed by changes in the molecular nuclear skeleton (such as molecular rearrangement or bond cleavage, etc.), resulting in the expected response product. If the frequency of the irradiated light matches only the energy required for the transition of the molecular vibrational level, the vibration of the molecule will be excited. In most cases, the excited molecule still belongs to the electronic ground state, and no photochemical reaction occurs. However, when the density of the irradiating light is very high, it is possible to force the molecules to absorb multiple photons simultaneously or continuously, elevate to a high-vibration excited state, and may cause the molecule to transition from the ground state to the electron-excited state, thereby generating a bond The rupture or rearrangement of the nuclear skeleton. This photochemical reaction was known as infrared photochemistry in the 1970s and is now more commonly referred to as vibrating photochemical reactions. This area has drawn great attention from the chemical community due to the emergence of high-power infrared lasers and the possibility of selective excitation of the bonds.