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Forward stimulated Raman scattering and backward stimulated Raman scattering (BSRS) are measured when an intense 532 nm nanosecond pulsed laser is focused into water and heavy water. The investigation reveals a significant observation: the formation of the ice VII structure exclusively occurs in the backward direction when optical breakdown takes place, provided that the input energy falls below 90 mJ for liquid water or 75 mJ for heavy water. This phase transition is attributed to secondary shock compression, which comes from energy transfer and compression between the BSRS in plasmas with the pump laser. The optical breakdown experiment under pre-pressure reveals that the shock compression in the back direction is approximately 2.3 times that of the forward direction. This research is useful for shock compression and dynamics in plasmas. [ABSTRACT FROM AUTHOR]

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) not only expands the spectral range of stimulated emission but also presents a way to delve into the intricate microscopic dynamics of matter. In this manuscript, SRS of O–O and O–H stretching vibrations in H2O–H2O2 solution is measured using 532 nm Nd:YAG laser. SRS peak intensities of O–O and O–H stretches are observed to engage in a competitive process, depending on the coupling direction of the excess electrons, which is determined by the recombination rate of H2O2 and H2O under laser-induced breakdown. Notably, a high-order (fifth order) SRS peak originating from H2O2 is detected, attributable to the Raman-active enhancement caused by surplus electrons and the amplification of vibration energy resulting from shockwaves. This experiment holds potential for advancing multi-wavelength selective regulation in terms of its contributions. [ABSTRACT FROM AUTHOR]