Experimental basics for femtosecond electron diffraction studies

Abstract

This paper provides a practical introduction to the current practice of femtosecond electron diffraction. We emphasize a general implementation suitable for a wide class of photoactive samples, including nonreversible samples. High density femtosecond electron pulses are required and the consequences for diffractometer design and sample preparation and handling are discussed. Finally, the real space structural analysis of strongly-driven melting in metals possible with our implementation is outlined.

Through a Window, Brightly: A Review of Selected Nanofabricated Thin-Film Platforms for Spectroscopy, Imaging, and Detection

“…The use of silicon nitride windows in creating sample cells and chambers has become increasingly prevalent, as has their use as sample supports; their use as a platform to host structural elements such as nanofluidic channels is a relatively new area of application and investigation. 16–29,36–58…”

“…17,38,39 In others, experimental conditions can present challenges as simple, but unyielding, as the necessity for vacuum conditions, or as pernicious as probe-induced sample damage. 38,39,134,135 Challenges can be additive and mutually amplifying in severity. The use of a sample container can play a similarly complex role.…”

“…17,38,39,[131][132][133] In some cases, the challenges arise from the properties of the sample, itself-high optical absorption or scattering cross-sections that require extremely short path lengths, for example. 17,38,39 In others, experimental conditions can present challenges as simple, but unyielding, as the necessity for vacuum conditions, or as pernicious as probe-induced sample damage. 38,39,134,135 Challenges can be additive and mutually amplifying in severity.…”

“…The utility of this SiN x material-or its thin-film brethren-for sample cell windows extends across the spectrum and into chargedparticle techniques. [17][18][19][20][35][36][37][38][39][40][41][42][43][44][45][53][54][55][56][57][58] We note, of course, that there is a tradition of alternative nanoscale sample chambers for spectroscopic studies, including vesicles, micelles, zeolites, and supramolecular entities. [136][137][138][139][140] Vesicles, for example, have been used in both ultrafast and single-molecule studies and use well-established formation protocols to use thin, but fragile, lipid bilayers to provide nanoscale confinement and low window signal (Fig.…”

“…141 The performance of this elegant solution is determined by sample properties such as the surface tension, viscosity, temperature, and vapor pressure, where solvent-optimization may lend generality to the study of solution samples using this approach. Nanofabricated equivalents of conventional sample cells and cuvettes, [17][18][19][20][35][36][37][38][39][40][41][42][43][44][45][53][54][55][56][57][58] have a number of advantages relating, primarily, to their generality of application. Their construction provides for straightforward manipulation, even by hand, and one has access to materials that can offer a greater range of sample compatibilities-either directly or through modifications-than the materials in specialized implementations such as phospholipid-based vesicles.…”