Study of Excited State Relaxation Pathways of 2,4,6-Trinitrobenzene-1,3,5-triamine Using Transient Absorption Spectroscopy

Author(s):

Frank De Lucia and Nhan Dang

Abstract:

Excited states are thought to play a role during the very early stages of energetic initiation. In this work, we used ultrafast pump-probe spectroscopy to resolve the excited states and subsequent relaxation pathways of the explosive 2,4,6-trinitrobenzene-1,3,5-triamine (TATB). A 400-nm, 35-fs laser pulse was used to pump the TATB into an excited state. We used transient absorption to analyze the excited state’s absorption features and lifetimes. We collected transient absorption spectra at various delay times relative to the pump pulse over a range of 0.5 to 30 ps to resolve the excited states. Using global lifetime analysis, we found two prominent excited states with lifetimes of 0.72 and 4.4 ps. Based on results from our experiments and the literature, there are two possible relaxation pathways: the relaxation to a triplet state and relaxation to a “hot” ground state/relaxed structure.