Generation of Intense Phase-Stable Femtosecond Hard X-ray Pulse Pairs

Coherent nonlinear spectroscopies and imaging in the X-ray domain provide direct insight into the coupled motions of electrons and nuclei with resolution on the electronic length and time scale. The experimental realization of such techniques will strongly benefit from access to intense, coherent pairs of femtosecond X-ray pulses. We have observed phase-stable X-ray pulse pairs containing more thank 3 x 10e7 photons at 5.9 keV (2.1 Angstrom) with about 1 fs duration and 2-5 fs separation. The highly directional pulse pairs are manifested by interference fringes in the superfluorescent and seeded stimulated manganese K-alpha emission induced by an X-ray free-electron laser. The fringes constitute the time-frequency X-ray analogue of the Young double-slit interference allowing for frequency-domain X-ray measurements with attosecond time resolution.Comment: 39 pages, 13 figures, to be publishe

Luminescent hybrid biocomposite films derived from animal skin waste

The leather industry generates approximately ten million tons of solid bio-wastes that can be used to synthesize various multifunctional materials with exciting properties. One such approach involves developing advanced hybrid materials, which is considered one of the key areas but the underdeveloped materials science discipline. This work explored methods to use collagen derived from leather industry bio-wastes to form hybrid films via two different ways: to produce luminescent carbon dots (Cdots) and develop hybrid films. The polymeric collagen was mixed with Cdots and reduced graphene oxide (rGO) to create flexible composite films that exhibit improved thermal, mechanical, electrical, and luminescent properties. The Cdot films displayed enhanced luminescence. The Kubelka-Munk transformation of the diffuse reflectance reveals a massive increase in absorbance in the visible light region with the addition of rGO. Besides, the developed films displayed electrical conductivity and weak ferromagnetic characteristics and showed enhanced biocompatibility. These findings highlight new avenues for converting industrial bio-wastes into useful multifunctional materials in scalable and inexpensive ways, thereby diminishing environmental pollution and enhancing environmental sustainability

Multifunctional Applications Enabled by Fluorination of Hexagonal Boron Nitride

Publication status: PublishedFunder: Shared Equipment AuthorityFunder: Electron Microscopy CenterFunder: Rice University; doi: http://dx.doi.org/10.13039/100007863Funder: Vanier Canada Graduate ScholarshipFunder: Natural Sciences and Engineering Research Council of Canada; doi: http://dx.doi.org/10.13039/501100000038Abstract2D materials exhibit exceptional properties as compared to their macroscopic counterparts, with promising applications in nearly every area of science and technology. To unlock further functionality, the chemical functionalization of 2D structures is a powerful technique that enables tunability and new properties within these materials. Here, the successful effort to chemically functionalize hexagonal boron nitride (hBN), a chemically inert 2D ceramic with weak interlayer forces, using a gas‐phase fluorination process is exploited. The fluorine functionalization guides interlayer expansion and increased polar surface charges on the hBN sheets resulting in a number of vastly improved applications. Specifically, the F‐hBN exhibits enhanced dispersibility and thermal conductivity at higher temperatures by more than 75% offering exceptional performance as a thermofluid additive. Dispersion of low volumes of F‐hBN in lubricating oils also offers marked improvements in lubrication and wear resistance for steel tribological contacts decreasing friction by 31% and wear by 71%. Additionally, incorporating numerous negatively charged fluorine atoms on hBN induces a permanent dipole moment, demonstrating its applicability in microelectronic device applications. The findings suggest that anchoring chemical functionalities to hBN moieties improves a variety of properties for h‐BN, making it suitable for numerous other applications such as fillers or reinforcement agents and developing high‐performance composite structures.</jats:p

Generation of Intense Phase-Stable Femtosecond Hard X-ray Pulse Pairs

Coherent nonlinear spectroscopies and imaging in the X-ray domain provide direct insight into the coupled motions of electrons and nuclei with resolution on the electronic length and time scale. The experimental realization of such techniques will strongly benefit from access to intense, coherent pairs of femtosecond X-ray pulses. We have observed phase-stable X-ray pulse pairs containing more than 3*107 photons at 5.9 keV (2.1 Å) with ~1 fs duration and 2-5 fs separation. The highly directional pulse pairs are manifested by interference fringes in the superfluorescent and seeded stimulated manganese Kα emission induced by an X-ray free-electron laser. The fringes constitute the time-frequency X-ray analogue of Young’s double-slit interference allowing for frequency-domain X-ray measurements with attosecond time resolution