Photochemistry by femtosecond pulse-train

飞秒脉冲序列光化学

• 批准号: 11440173
• 负责人: WADA Akihide
• 金额: $ 9.34万
• 依托单位: Tokyo Institute of Technology
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (B).
• 财政年份: 1999
• 资助国家: 日本
• 起止时间: 1999 至 2000
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-11440173/
• 关键词: pulse shaping; Genetic Algorithm; ultrafast phenomena; pulse train; coherent phonon; femtosecond laser; パルストレイン; コヒーレントフォノン; 発光スペクトルの制御; パルス圧縮

In this research project, we have constructed a pulse-shaping system consisting of a mode-locked femtosecond laser and pulse-shaper. The control of pulse shape is accomplished using a programmable pulse shaper based on a Fourier transform technique where a liquid crystal spatial light modulator (LCSLM), consisting of the polarizer and liquid crystal display (LCD) which has the rectangular pixels with the width of 0.1 mm, adjusts the intensity and the phase of each spectral component of the laser pulses in the frequency domain. Furthermore, the system was controlled by the a genetic algorithm (GA) which is a powerful tool to find a pulse shape suitable for a specific physical/chemical process without the knowledge of the input pulses and the detailed structure of samples.The GA is a multi-objective optimization method which mimics process actually taking place in the biological evolution process consisting of selection, crossover, and mutation of individuals. For the pulse shaping system controlled by the GA, the modulation pattern printed on the LCD in the SLM is regarded as the pattern of nucleotide sequence in gene by considering the pixel of the SLM as the base pair of gene. Then, the system evolves the modulation pattern in search of the pulse shapes suitable for a specific process on the basis of feedback from the experiment. In the progress of the pattern evolution, the value of the experimental output corresponds to the fitness for the environment of the organism.We tried to control the STE creation process in perylene crystal using the system. It was found that the intensity ratio of E-type STE emission to Y-type STE emission could be changed as a function of the pulse shape.

在这个研究项目中，我们构建了一个由锁模飞秒激光器和脉冲整形器组成的脉冲整形系统。脉冲形状的控制是使用基于傅里叶变换技术的可编程脉冲整形器来完成的，其中液晶空间光调制器（LCSLM）由偏振器和液晶显示器（LCD）组成，液晶显示器（LCD）具有宽度为0.1的矩形像素mm，调整频域中激光脉冲的每个光谱分量的强度和相位。此外，该系统由遗传算法（GA）控制，遗传算法是一种强大的工具，可以在不了解输入脉冲和样品详细结构的情况下找到适合特定物理/化学过程的脉冲形状。多目标优化方法，模拟生物进化过程中实际发生的过程，包括个体的选择、交叉和变异。对于由GA控制的脉冲整形系统，将SLM中的像素视为基因的碱基对，将SLM中的LCD上打印的调制图案视为基因中的核苷酸序列的图案。然后，系统根据实验反馈改进调制模式，寻找适合特定过程的脉冲形状。在模式演化的过程中，实验输出的值对应于生物体对环境的适应度。我们试图利用该系统来控制苝晶体中STE的产生过程。发现E型STE发射与Y型STE发射的强度比可以作为脉冲形状的函数而改变。

项目成果

A.Bandara,J.Kubota,K.Onda,A.Wada,K.Domen,and C.Hirose: "Short-lived reactive formate species on NiO(111)observed by picosecond temperature jump"Surface Science. 433/435. 83-87 (1999)

A.Bandara、J.Kubota、K.Onda、A.Wada、K.Domen 和 C.Hirose：“通过皮秒温度跳跃观察到 NiO(111) 上的短寿命反应性甲酸盐物种”表面科学。

H.Takaba,A.Wada, et al.: "Vibrational Sum-Frequency Observation of Synthetic Diamonds"Diamond and Related Materials. (accepted).

H.Takaba，A.Wada，等人：“合成金刚石的振动和频观察”金刚石和相关材料。

H.Takaba,A.Wada, et al.: "Vibrational Surm-Frequency Observation of Synthetic Diamonds"Diamond and Related Materials. (accepted).

H.Takaba，A.Wada，等人：“合成金刚石的振动频率观察”金刚石和相关材料。

H.Takaba, A.Wada, et al.: "Vibrational Sum-Frequency Observation of Synthetic Diamonds"Diamond and Related Materials. (in printing).

H.Takaba、A.Wada 等人：“合成金刚石的振动和频观察”金刚石和相关材料。

溝口隆一,恩田健,和田昭英, et al.: "フェムト秒パルス波形探索システム"分光研究. 49. 287-291 (2000)

Ryuichi Mizoguchi、Ken Onda、Akihide Wada 等：“飞秒脉冲波形搜索系统”光谱研究 49. 287-291 (2000)。