In the first instants ... ultrafast views of radiation effects

In the first instants following high-energy electronic excitation of a soli d, electrons and holes scatter from one another while establishing the init ial partition of excitation among available states, and scatter from phonon s while cooling to a thermalized population. If significant local lattice r elaxation or self-trapping occur, the mobility and recombination time may b e strongly altered. Electron capture and/or defect formation can culminate in luminescence for scintillation detection or in stored energy that may be the basis for imaging or dosimetry. It is now possible to observe directly and measure some of the consequences of excitation on fs and ps time scale s. (C) 2001 Elsevier Science Ltd. All rights reserved.