Isotropic emission components in splintering central collisions: $\left(17\mathrm{}-115\right)A$ MeV ${}^{40}\mathrm{Ar}\mathrm{}+\mathrm{}\mathrm{Cu},$ Ag, Au

The ensemble of charged isotropically emitted ejectiles is studied for central collisions of $\left(17\mathrm{}-115\right)A$ MeV ${}^{40}\mathrm{Ar}\mathrm{}+\mathrm{}\mathrm{Cu},$ Ag, Au. Measurements of average multiplicities, spectral slopes, and masses of the heaviest fragments are compared to statistical models for multifragmentation or sequential evaporation. The multifragmentation models predict much more complete nuclear disassembly than is observed. The evaporation model reproduces the data much more closely except for the spectra of $Z=1\mathrm{}$ ejectiles. The kinetic energies of $Z=1\mathrm{}$ and 2 ejectiles are much less than found for $1A$ GeV ${}^{197}\mathrm{Au}{+}^{12}\mathrm{C}$ for similar energy depositions. Entrance channel dynamics seem to affect the isotropic emission ensembles, often taken to define an equilibrated emission source.