Provide an introduction to the invited speakers and an overview of the scientific presentations in the session.
Gas-phase ultrafast electron diffraction (UED) has become a powerful tool for capturing molecular dynamics with femtosecond temporal and atomic spatial resolutions, enabling direct observation of phenomena such as photo-dissociation, ring-opening reactions, and nuclear wavepacket motion through conical intersections. Despite significant progress, several challenges remain: temporal resolution...
The five-member ring isomers oxazole and isoxazole (C3H3NO) are an interesting model system for studying UV-induced isomerization and dissociation since the different types of bonds in both isomers (C-N-C-O vs C-N-O-C) are predicted to lead to very different reaction products and dynamics. I will present time-resolved product yields for both isomers obtained from a recent GUED experiment and...
Laser-induced streaking (LIS) of electron beam, first observed by Zewail group back in 1994, is a unique phenomenon in UED that is often used to conveniently identify time-zero in UED experiments. In the gas phase, LIS originates from plasma field created by strong field ionization of sample molecules, hence named as “photoionization-induced lensing” by Zewail. Separately, LIS can also be...
High rep-rate SRF-Linac based XFEL like LCLS-II has a stringent requirement on the limit of the dark current from the injector RF gun. In this talk, we will present our recent work on mitigating the LCLS-II gun dark current by re-designing the photo cathode. New cathode plugs with ~1mm insertion have been designed, manufactured and commissioned at LCLS-II. They successfully reduce the gun...
Two high-gradient 1.6-cell normal-conducting RF photoinjectors at C-band were designed for operation at the Cathodes And Radiofrequency Interaction in Extremes (CARIE) facility at Los Alamos National Laboratory (LANL). The first photoinjector cavity uses a planar copper cathode and has been fabricated and tuned at low power. The second photoinjector cavity was designed for using INFN-style...
Four-dimensional scanning transmission electron microscopy, where the full forward scattering distribution of the electron beam is recorded by a 2D pixelated detector at each position in a scan, provides a wealth (a deluge?) of information about the sample. Detectors with high dynamic range enable quantitative analysis of the diffraction data, and their high speed (10-100k fps) allows us to...
Laser technologies for generating sub-picosecond pulses at different wavelengths have propelled photocathodes to the forefront of electron sources. By leveraging nanofabrication techniques, photocathode research now promises to deliver sources for beams with sub-micron transverse dimensions and sub-nanometer emittances. The techniques for fabricating these sources are versatile, allowing them...
When driven to extreme temperatures, solid density matter can exhibit properties different than those found at ambient conditions. Measurement of properties, in particular transport properties such as the electrical conductivity, has been possible by heating thin films of material using ultrafast lasers. However, interpretation of experimental results and comparison with theoretical prediction...
Experimental study of early damage in nuclear damage has been very challenging due to low quantity and small size of defects. Therefore, being able to reliably validate modelling techniques of primary damage in nuclear materials has not been possible. Recent, advances in UED experiments has made it possible to study the dynamics of the material due to laser excitation. By comparing the signals...
To be determined
