Iwamoto Naoki, Schwartz Charles J, Jochim Bethany, Raju P Kanaka, Feizollah Peyman, Napierala J L, Severt T, Tegegn S N, Solomon A, Zhao S, Lam Huynh, Wangjam Tomthin Nganba, Kumarappan V, Carnes K D, Ben-Itzhak I, Wells E
Department of Physics, Augustana University, Sioux Falls, South Dakota 57197, USA.
J.R. Macdonald Laboratory, Department of Physics, Kansas State University, Manhattan, Kansas 66506, USA.
J Chem Phys. 2020 Feb 7;152(5):054302. doi: 10.1063/1.5129946.
Using the CDOH isotopologue of methanol, the ratio of DH to D formation is manipulated by changing the characteristics of the intense femtosecond laser pulse. Detection of DH indicates a formation process involving two hydrogen atoms from the methyl side of the molecule and a proton from the hydroxyl side, while detection of D indicates local formation involving only the methyl group. Both mechanisms are thought to involve a neutral D moiety. An adaptive control strategy that employs image-based feedback to guide the learning algorithm results in an enhancement of the DH/D ratio by a factor of approximately two. The optimized pulses have secondary structures 110-210 fs after the main pulse and result in photofragments that have different kinetic energy release distributions than those produced from near transform limited pulses. Systematic changes to the linear chirp and higher order dispersion terms of the laser pulse are compared to the results obtained with the optimized pulse shapes.
使用甲醇的CDOH同位素异构体，通过改变高强度飞秒激光脉冲的特性来控制DH与D形成的比率。检测到DH表明形成过程涉及分子甲基侧的两个氢原子和羟基侧的一个质子，而检测到D表明仅涉及甲基的局部形成。两种机制都被认为涉及中性D部分。一种采用基于图像反馈来指导学习算法的自适应控制策略，使DH/D比率提高了约两倍。优化后的脉冲在主脉冲之后具有110 - 210飞秒的二级结构，并产生具有与近变换极限脉冲产生的光碎片不同的动能释放分布的光碎片。将激光脉冲的线性啁啾和高阶色散项的系统变化与使用优化脉冲形状获得的结果进行比较。
