Light-Induced In Situ Transmission Electron Microscopy─Development, Challenges, and Perspectives

Abstract

Transmission electron microscopy is a basic technique used for examining matter at the highest magnification scale available. One of its most challenging branches is in situ microscopy, in which dynamic processes are observed in real time. Among the various stimuli, like strain, temperature, and magnetic or electric fields, the light−matter interaction is rarely observed. However, in recent years, a significant increase in the interest in this technique has been observed. Therefore, I present a summary and critical review of all the in situ experiments performed with light, various technical possibilities for bringing radiation inside the transmission electron microscope, and the most important differences between the effects of light and electrons on the studied matter. Finally, I summarize the most promising directions for further research using light excitation.

Watching Plasmon-Induced Nanoparticle Ostwald Ripening

“…The structural evolution of nanomaterials under perturbative conditions has been studied by optical spectroscopy, − X-ray techniques, − and in situ transmission electron microscopy (TEM). − In particular, TEM enables studies of such dynamics at the single-nanoparticle level with atomic spatial resolution and millisecond temporal resolution − or faster using a pump–probe method. ,, However, TEM has rarely been used to probe structural transformations induced by light excitation . The few in situ TEM studies of nanomaterials under light have uncovered unexpected photocatalytic pathways , and photocatalyst activation dynamics, among a host of interesting fast and ultrafast dynamics. ,,− However, real-time TEM imaging of the plasmon-induced structural evolution of plasmonic nanostructures remains an unmet opportunity.…”

“…36,39,40 However, TEM has rarely been used to probe structural transformations induced by light excitation. 41 The few in situ TEM studies of nanomaterials under light have uncovered unexpected photocatalytic pathways 42,43 and photocatalyst activation dynam-ics, 44 among a host of interesting fast and ultrafast dynamics. 36,40,45−53 However, real-time TEM imaging of the plasmon-induced structural evolution of plasmonic nanostructures remains an unmet opportunity.…”

On-Chip Light-Incorporated In Situ Transmission Electron Microscopy of Metal Halide Perovskite Materials

“…Atomic force microscopy (AFM) and synchrotron/laboratory X-ray diffraction are popular methods exploited for studying light responses in MHPs, as these measurements are performed mostly in non-vacuum and open environments where light can be incorporated easily. , Still, AFM and X-ray probes are limited to revealing either morphological or statistical phase information, calling for the use of analytical transmission electron microscopy (TEM). TEM can simultaneously provide both morphological and phase information, and more importantly, unlock an extremely high spatial resolution (from the atomic to nanometer scales). − The recent development of TEM characterization for MHPs has been proven successful with regard to the unprecedented local structure/phase information and insightful knowledge achieved. − Nevertheless, it remains an utmost challenge to incorporate a light component into TEM characterization, which has only been tried in only a handful of studies for non-MHP materials systems. − Generally, commercially available in situ TEM platform setups can provide controls only on temperature, − atmosphere, liquid, , and electrical bias, , restricting the study of any light effects on the transformation and degradation of MHPs. , …”

In Situ Electron Microscopy of Transformations of Copper Nanoparticles under Plasmonic Excitation

“…Similar exploration of structural dynamics of metal nanostructures induced by plasmonic excitation requires a TEM equipped for probing materials under light. 41 Opticalexcitation-coupled TEM has been used to gain insights into photocatalytic activity 42−45 and fast and ultrafast dynamics. 46−54 Here we used a TEM equipped for optical excitation of the specimen 55 to probe the structural evolution of Cu-based nanoparticles, a canonical plasmonic nanostructure.…”

“…The dynamic evolution of nanostructures under stimulation has been studied by optical spectroscopy, ,− X-ray techniques, − and transmission electron microscopy (TEM). − Studies have revealed reshaping ,− and changes in elemental compositions ,,,, in response to perturbations such as heating and exposure to reactive species. Similar exploration of structural dynamics of metal nanostructures induced by plasmonic excitation requires a TEM equipped for probing materials under light . Optical-excitation-coupled TEM has been used to gain insights into photocatalytic activity − and fast and ultrafast dynamics. − …”