Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830, USA.
Published: August 2023
AI Article Synopsis
Article Abstract
Every material experiences atomic and molecular motions that are generally termed vibrations in gases and liquids or phonons in solid state materials. Optical spectroscopy techniques, such as Raman, infrared absorption spectroscopy, or inelastic neutron scattering (INS), can be used to measure the vibrational/phonon spectrum of ground state materials properties. A variety of optical pump probe spectroscopies enable the measurement of excited states or elucidate photochemical reaction pathways and kinetics. So far, it has not been possible to study photoactive materials or processes in situ using INS due to the mismatch between neutron and photon penetration depths, differences between the flux density of photons and neutrons, cryogenic temperatures for INS measurements, vacuum conditions, and a lack of optical access to the sample space. These experimental hurdles have resulted in very limited photochemistry studies using INS. Here we report on the design of two different photochemistry sample sticks that overcome these experimental hurdles to enable in situ photochemical studies using INS, specifically at the VISION instrument at Oak Ridge National Laboratory. We demonstrate the use of these new measurement capabilities through (1) the in situ photodimerization of anthracene and (2) the in situ photopolymerization of a 405 nm photoresin using 405 nm excitation as simple test cases. These new measurement apparatus broaden the science enabled by INS to include photoactive materials, optically excited states, and photoinitiated reactions.
Salmonella is a poultry-borne pathogen causing numerous human outbreaks in the U.S. Consequently, Salmonella, along with other pathogens, can be found in wastewater generated from poultry processing.
Resonant inelastic X-ray scattering (RIXS) is an ideal X-ray spectroscopy method to push the combination of energy and time resolutions to the Fourier transform ultimate limit, because it is unaffected by the core-hole lifetime energy broadening. Also, in pump-probe experiments the interaction time is made very short by the same core-hole lifetime. RIXS is very photon hungry so it takes great advantage from high-repetition-rate pulsed X-ray sources like the European XFEL.
Given the severe loss of species richness across diverse ecosystems, there is an urgent need to assess and monitor biodiversity on a global scale. The analysis of environmental DNA (eDNA), referring to any DNA extracted from environmental samples and subsequently sequenced, is a promising method for performing such biodiversity related studies. However, a comprehensive understanding of the factors that drive distinct eDNA degradation rates under different environmental conditions is currently missing, which limits the spatiotemporal interpretations that are possible from the eDNA-based detection of species.
Researchers are working on creating synthetic soft materials that mimic living organisms' behaviors, specifically those that can sense and adapt to their environments.
This study focuses on a hybrid hydrogel made from peptide amphiphile nanofibers and photoresponsive materials that can swim using aligned ferromagnetic nanowires and respond to light.
The findings showcase the potential of using hybrid polymers that combine supramolecular and covalent structures to develop intelligent systems that can autonomously react to their surroundings.
Many of the features of SERS, such as its high sensitivity, molecular specificity and speed of analysis make it attractive as an analytical technique. However, SERS currently remains a specialist technique which has not yet entered the mainstream of analytical chemistry. Therefore, this review draws out the underlying principles for analytical SERS and provides practical tips and tricks for SERS quantitation.
