Three tri-branched oligomers based on 1,3,5-triazine with large two-photon absorption cross-sections and good optical limiting properties were investigated by UV–Visible, femtosecond Z-scan and one/two-color pump-probe measurements. The two-photon absorption cross-section results measured at a wavelength of 800[Formula: see text]nm were found decreasing with the number of fluorene groups in each branches. The optical limiting properties were also investigated and a two-photon absorption mechanism was proposed. One/two-color pump-probe measurements were also used to further investigate the ultrafast responses of these tri-branched oligomers. The ultrafast response results indicated that after excitation, the tri-branched oligomers will first undergo a fast process to form an intramolecular charge transfer state followed by relaxation of the intramolecular charger transfer state of approximately several hundred ps.

中文翻译：

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基于 1,3,5-三嗪的三种低聚物的光限特性和超快响应

通过紫外可见、飞秒 Z 扫描和单色/双色泵浦探针测量研究了基于 1,3,5-三嗪的三种三支化低聚物，具有大的双光子吸收截面和良好的光学限制特性。在波长为 800 [公式：见正文] nm 处测量的双光子吸收截面结果发现随着每个分支中芴基团的数量而减少。还研究了光学限制特性，并提出了双光子吸收机制。一/二色泵浦探针测量也用于进一步研究这些三支化低聚物的超快响应。超快响应结果表明，激发后，