Scanning the energy dissipation process of energetic materials based on excited state relaxation and vibration–vibration coupling

• 来源期刊: 中国物理B（英文版）
• 关键词: energy dissipation charge transfer transient absorption coherent anti-stokes Raman scattering (CARS)
• 年，卷（期）: 2018,（10）
• 页码范围: 258-263
• 页数: 6页
• 语种: 英文
• DOI: 10.1088/1674-1056/27/10/104205

摘要

The energy dissipation mechanism of energetic materials (EMs) is very important for keeping safety. We choose nitrobenzene as a model of EM and employ transient absorption (TA) spectroscopy and time-resolved coherent anti-stokes Raman scattering (CARS) to clarify its energy dissipation mechanism. The TA data confirms that the excited nitrobenzene spends about 16 ps finishing the twist intramolecular charge transfer from benzene to nitro group, and dissipates its energy through the rapid vibration relaxation in the initial excited state. And then the dynamics of vibrational modes (VMs) in the ground state of nitrobenzene, which are located at 682 cm?1 (v1), 854 cm?1 (v2), 1006 cm?1 (v3), and 1023 cm?1 (v4), is scanned by CARS. It exhibits that the excess energy of nitrobenzene on the ground state would further dissipate through intramolecular vibrational redistribution based on the vibrational cooling of v1 and v2 modes, v1 and v4 modes, and v3 and v4 modes. Moreover, the vibration–vibration coupling depends not only on the energy levels of VMs, but also on the spatial position of chemical bonds relative to the VM.