DYNAMICS OF EXCITED AND IONIC STATES OF N,N,N',N'-TETRAMETHYL-P-PHENYLENEDIAMINE IN POLY(METHYL METHACRYLATE) UNDER ABLATION CONDITION

The nanosecond transient dynamics of N,N,N',N'-tetramethyl-p-phenylene diamine in poly(methyl methacrylate) has been investigated under ablat ion condition. Time-resolved spectroscopic data can be interpreted in terms of the dynamics of the lowest excited singlet and triplet states and the cation of TMPD. The decay processes of all the detected trans ients became rapid with an increase in the laser fluence. It is shown directly that TMPD absorbs about eight 248 nm photons during a nanosec ond laser pulse at the ablation threshold of 220 mJ/cm(2). These resul ts are well explained by cyclic multiphotonic absorption mechanism whe re dopant transients work as repetitive absorbers of laser photons.