Greenfield Margo T, McGrane Shawn D, Bolme Cindy A, Bjorgaard Josiah A, Nelson Tammie R, Tretiak Sergei, Scharff R Jason
Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States.
J Phys Chem A. 2015 May 21;119(20):4846-55. doi: 10.1021/acs.jpca.5b02092. Epub 2015 May 7.
Pentaerythritol tetranitrate (PETN), a high explosive, initiates with traditional shock and thermal mechanisms. In this study, the tetrazine-substituted derivative of PETN, pentaerythritol trinitrate chlorotetrazine (PetrinTzCl), is being investigated for a photochemical initiation mechanism that could allow control over the chemistry contributing to decomposition leading to initiation. PetrinTzCl exhibits a photochemical quantum yield (QYPC) at 532 nm not evident with PETN. Using static spectroscopic methods, we observe energy absorption on the tetrazine (Tz) ring that results in photodissociation yielding N2, Cl-CN, and Petrin-CN as the major photoproducts. The QYPC was enhanced with increasing irradiation intensity. Experiment and theoretical calculations imply this excitation mechanism follows sequential photon absorption. Dynamic simulations demonstrate that the relaxation mechanism leading to the observed photochemistry in PetrinTzCl is due to vibrational excitation during internal conversion. PetrinTzCl's single photon stability and intensity dependence suggest this material could be stable in ambient lighting, yet possible to initiate with short-pulsed lasers.
季戊四醇四硝酸酯（PETN）是一种烈性炸药，通过传统的冲击和热机制引发爆炸。在本研究中，正在研究PETN的四嗪取代衍生物——季戊四醇三硝酸氯四嗪（PetrinTzCl）的光化学引发机制，该机制可控制导致引发爆炸的分解过程中的化学反应。PetrinTzCl在532nm处表现出PETN所没有的光化学量子产率（QYPC）。使用静态光谱方法，我们观察到四嗪（Tz）环上的能量吸收，导致光解离产生N2、Cl-CN和Petrin-CN作为主要光产物。QYPC随着照射强度的增加而增强。实验和理论计算表明，这种激发机制遵循顺序光子吸收。动态模拟表明，导致PetrinTzCl中观察到的光化学现象的弛豫机制是由于内转换过程中的振动激发。PetrinTzCl的单光子稳定性和强度依赖性表明，这种材料在环境光下可能是稳定的，但有可能用短脉冲激光引发爆炸。
