Basic generation of PINEM signals : (a) at t < 0, the electron wave packet of the microscope arrives at the object, a carbon nanotube, before the femtosecond laser pulse and no spatio-temporal overlap occurs between the different fields; (b) at t = 0, the overlap is maximum between photon EM field, the electron wave packet and the evanescent optical field generated by the optical field; (c) at t = 0 or immediately positive, the interaction is maximum and the electron can gain or lose energies equal to integer numbers of the fs laser photon energies; (d) electron energy spectra recorded at two different delay times between the electron and photon beam on the carbon nanotube: for t < 0, only an energy loss spectrum with a single weak peak around 7 eV is visible. But for t = 0, the spectrum exhibits multiple quanta of energy corresponding to the absorption or emission of photons as illustrated in the inset of (c), (from Barwick et al. [161]).