Abstract

The temporal and spectral characteristics of a detonating crystalline sample of tetramethyl dioxetane (TMDX) are studied after multiphoton excitation with single laser shots from a CO₂ TEA laser at 10.25 μm. Time-dependent studies indicate that the emission consists of two components, which contribute almost equally to the total number of emitted photons. A fast emission rises after the laser pulse with an incubation period of ~1 μs and decays in ~500 ns. A slow component appears at a delay of ~10 μs and has a lifetime of ~100 μs. The temporal profile of the emission is strongly dependent on the initial laser power. The incubation period of the fast component decreases with increasing laser power at a rate of 1.6 μs per 1-J/cm² laser fluence. Furthermore, a larger proportion of the molecules are contained in the fast component as the laser power is increased. These results indicate that the intense short-lived emission is only possible when a large initial population of excited TMDX is created. The spectral profile of the emission resulting from solid TMDX at short times is remarkably narrow with a FWHM of 40 nm peaking at 440 nm. This is in contrast to gas-phase acetone phosphorescence (λ_max = 460 nm) and fluorescence (λ_max = 405 nm), which each have a FWHM of ~120 nm. Based on the time scale and the narrow spectral width, we tentatively assign the fast component of the emission to an excited singlet species in the solid TMDX sample.

© 1986 Optical Society of America