Unveiling a laser-free 300 kV stroboscopic TEM with a projected sub 10-ps temporal resolution

For the last several decades, time-resolved transmission electron microscopes (TEM) exploring the sub-microsecond timescale have relied on laser-actuated photocathodes for precisely timed, pulsed probe beams, while another laser beam, typically locked to or split-off from the probe-generating laser, delivers the sample stimulus (pump). These instruments can study a wide range of laser-driven phenomena in both stroboscopic and single-shot modes, for repeatable and one-time events, respectively. However, not all processes of interest are amenable to the laser-driven approach. In the last three years, this collaboration has made substantial progress towards pioneering a new kind of time-resolved TEM, complementary to the existing laser-based techniques. Using RF beam-modulators, we can achieve a pulsed electron beam at 10% duty cycle with continuously tuneable GHz and MHz pulse rates. This RF-modulator approach extends the application of time-resolved TEM to in operando, electromagnetically-pumped experiments up to 20 GHz.

Today, we are at the edge of unveiling a pair of these microscopes. We will briefly discuss how they work, and the activities that NIST has recently undertaken, which includes RF holder and instrument benchmarking designs, to prepare for the instruments’ debut.