The Electronic Excitation of 2,4,6-Triamino-1,3,5-Trinitrobenzene in DMSO Solution under Indirect Ultrafast Heating: A Comparison to Results Obtained by Optical Pumped Method

The primary motivation for this work is the desire to observe and understand the heat-pumped mechanism that drives electronic excitations of 2,4,6-triamino-1,3,5-trinitrobenzene (TATB) under ultrafast heating. In this work, using the indirect flash heating technique coupled with transient visible absorption spectroscopy, we investigate the electronic excitations in excited states of TATB in dimethyl sulfoxide solution that are excited by heat pulses with a pulse width of 3.5 ps and a temperature rise time of 1.5 ps. In an effort to distinguish the heat-driven mechanism for electronic excitation of TATB from the optically pumped mechanism, the obtained transient absorption (TA) data are then compared with the TA data obtained using the ultrafast optical pump probe technique. Prominent features attributed to thermally induced perturbations on the electronic structure of TATB molecules being promoted to the excited state were observed. Comparisons of the TA spectrum of the sample to that obtained by optical excitation reveal that under heating, electronic excitation of TATB molecules occur at lower energies. A hypothesis for the heat-driven mechanism of the electronic excitation is discussed to support the observations.