SUBPICOSECOND TIME-RESOLVED SPECTROSCOPY OF ENERGETIC MATERIALS - THENITROMETHANE AND NITRO-STILBENES

Using sub-picosecond CARS experiment we observed direct photolysis of liquid nitromethane after pulse excitation at 299 nm. We measured the dynamic behaviour under excitation of three main ground state Raman li nes at 917 cm(-1), 1400 cm(-1) and 2968 cm(-1). We deduced an excited state lifetime of 1.1 +/-0.3 ps and we measured a photolysis quantum y ield at 299 nm of 24% +/-5%. Using ''pump-probe'' experiments we obser ved the evolution of excited states of eight nitro-stilbene derivative s including 2,4,6,2',4',6'-hexanitro-stilbene (HNS). In the studied co mpounds important non-radiative desexcitation channels have been obser ved and their possible role on explosive process is discussed.