In this seminar, the recent developments in ultrafast electron microscopy will be discussed. The design and implementation of a new fs-resolved TEM will be discussed, demonstrating the ability to obtain high coherence, spatial, energy and time resolution by careful engineering of the gun elements. The gun elements of our JEOL JEM2100 are modified to accomodate an alluminum mirror used to stirr the beam towards the LaB6 photocathode. Also, a C0 lens is added immediately after the gun section of the TEM. This extra lens has the purpose of collecting as many photoemitted electrons as possible when operating with low currents in time-resolved mode. We show that these modifications do not affect the performances of the TEM in conventional static operation. The spatial resolution was tested on a gold nanoparticle obtaining clear lattice fringes. Furthermore, the addition of the C0 lense is shown to imrpove the energy resolution in EELS, because it allows to operate with a lower current in the filament, thus reducing space charge effects, while preserving the birghtness of the beam. 
The potential of these techniques will be discussed via a series of examples including graphite thin films, nanotubes, and more recent results obtained on the charge density wave system TaS2. 
The combination of time-resolved diffraction, imaging and EELS, provided an unprecendented understanding of the intimate relation between charges and ions in the photoinduced evolution of graphite films. The microscopic description of these phenomena will be presented and an overview for the future perspectives of these tools in condensed matter physics will be given.