Experimental and computer simulation study of delayed fluorescence decay from irradiated n-dodecane solutions of TMPD

A computer model of the formation of molecular excited states in irradiated alkane solutions was applied successfully to the analysis of the experimental delayed fluorescence decays measured in the range 0-250 ns after X-ray pulsed irradiation of n-dodecane solutions of N,N,N′,N′-tetramethyl-para-phenylenediamine (TMPD). The modeling demonstrated that a track produced by 20-keV X-ray quanta in n-dodecane in the studied time range could be described by a set of isolated spherical spurs containing 4-5 ion pairs. The radius of such “effective” spurs were found to be about 5 nm for four pairs or 9-10 nm for five pairs.