  Ultra-fast transmission electron microscopy (UTEM) combines sub-picosecond
time-resolution with the versatility of TEM spectroscopies. It allows one to
study the dynamics of materials properties combining complementary techniques.
However, until now, time-resolved cathodoluminescence, which is expected to
give access to the optical properties dynamics, was still unavailable in a
UTEM. In this paper, we report time-resolved cathodoluminescence measurements
in an ultrafast transmission electron microscope. We measured lifetime maps,
with a 12 nm spatial resolution and sub-nanoseconds resolution, of
nano-diamonds with a high density of NV center. This study paves the way to new
applications of UTEM and to correlative studies of optically active
nanostructures.
