Laser Initiated Explosions and Chemiluminescence

Explosions can be induced in mixtures of SF6with appropriate fuels, by a single pulse of a free running CO2 laser ≈1.5 μs [full width at half maximum (FWHM)]. A typical threshold for initiation of reaction was somewhat above 4 J for a 1:1 mixture of SF6 and SiH4, at a total pressure of 10 torr, with the unfocused beam illuminating 8 cm2 of cell area. High levels of luminosity were generated covering both the near ultraviolet, visible, and infrared. The spectral and temporal characteristics of the following fuels and fuel-oxidizer combinations (with SF6 present) are summarized: the most prominent emitter from SiH4 is S*2, B3∑–u; Sn(CH3)4 + N2O [SnO*; SnF*]; Pb(CH3)4+ N2O (PbO*; PbF*; PbS*]; Bi(CH3)3 + N2O [BiF*]; B2H6 with and with out N2O [BO*; BO*2; S*2]. Several atomic lines were also recorded. Estimates of the energy density deposited by the laser pulse suggest that initiation of rapid reaction was primarily due to attack of superexcited SF6by highly reducing radical species.