Search

Although shock experiments are traditionally performed in large facilities, tabletop experiments that provide convenient high-throughput shock testing have been growing in importance. Here, we describe tabletop experiments using a shock compression microscope that features a pulsed 0–6 km/s laser flyer plate launcher and a photon Doppler velocimeter. We also describe methods to mass-produce flyer plates and targets to achieve high throughput. We explain how to condition a laser beam to launch flyers that provide reproducible short-rise time impacts with minimal tilt, and we present a number of applications including measuring shock propagation in nanoporous media, a simple way to describe shock wave energy absorption, the use of photoemissive probes such as organic dyes or quantum dots to study shocked inhomogeneous media, the development of an apparatus to measure optical absorption in shocked media, methods to study and measure the temperature of shocked energetic materials in the form of plastic-bonded explosives and in a form that allows us to observe hot spots in real time, and studies of the shocked interface between a metal fuel and a ceramic oxidizer. Finally, a brief perspective is presented describing new possibilities for future research of a diverse set of applications including the chemistry of shocked water and biological systems, dense plasmas, and the use of laser-launched flyer plates as surrogates for hypersonic vehicles. [ABSTRACT FROM AUTHOR]

Stimulated Raman scattering (SRS) spectra of the OH stretching vibrations of pure water and 2‐nm Si quantum dots (Si QDs) water solution have been investigated under different pump laser energies. Simultaneously, we have studied the spontaneous Raman spectra of pure water and Si QDs water solution at room temperature and atmospheric pressure. The results show that SRS intensity of Si QDs water solution is an order of magnitude higher than that of pure water at the same laser energy, which indicates that Si QDs enhance the SRS intensity of water molecules. The QDs enhancement SRS mechanism is attributed to the increase of third‐order nonlinear Raman susceptibility from the electric fields induced by the exciton effect of Si QDs. Stimulated Raman scattering (SRS) intensity of Si quantum dots (Si QDs) water solution is an order of magnitude higher than that of pure water.The increase of the third‐order nonlinear polarizability in water molecules is induced from the exciton effect of Si QDs.Due to Si QDs having a self‐absorption effect, the most obvious enhancement effect appears at laser energy of 110 mJ. [ABSTRACT FROM AUTHOR]

The structure of liquid water is strongly influenced by Si quantum dots (Si QDs). We employed Raman spectroscopy to investigate how Si QDs affect the icing point of water. In contrast with the Raman spectra of pure water, Raman spectra of Si QDs water solutions exhibit some distinct characteristic features. The Raman spectra present that liquid- ice I h phase transition takes place at 264 and 266 K in 5 and 2 nm Si QDs solutions respectively, which is higher than that of pure water (257 K). These phenomena are contributed to the electric field generated by Si QDs and the hydrogen bonds formed between silanol groups and water molecules. The results can open the way to understand the interaction between water molecules and quantum dots in some environments. • We employ Raman spectroscopy to study how Si QDs affect the icing point of water. • Si QDs can increase the icing point of water by H-bonds and electric field. • The icing point is dependent on the size of the Si QDs due to the suface effect. [ABSTRACT FROM AUTHOR]