Onset of ice VII phase during ps laser pulse propagation through liquid water
At a Glance
Section titled âAt a Glanceâ| Metadata | Details |
|---|---|
| Publication Date | 2017-01-01 |
| Journal | AIP conference proceedings |
| Authors | V. Rakesh Kumar, P. Prem Kiran |
| Institutions | University of Hyderabad |
| Citations | 1 |
| Analysis | Full AI Review Included |
6CCVD Technical Documentation: Analysis of Dynamic High-Pressure Ice VII Formation
Section titled â6CCVD Technical Documentation: Analysis of Dynamic High-Pressure Ice VII FormationâThis document analyzes the research article âOnset of ice VII phase during ps laser pulse propagation through liquid waterâ (AIP Conf. Proc. 1793, 090001, 2017). The study focuses on generating extreme GPa-level pressures dynamically using picosecond (ps) laser pulses to induce phase transitions in liquid water, a field highly reliant on the extreme mechanical and optical properties of CVD diamond.
Executive Summary
Section titled âExecutive SummaryâThe following points summarize the core technical achievements and the corresponding value proposition for 6CCVDâs advanced diamond materials:
- Dynamic High-Pressure Generation: The research successfully induced the formation of the high-pressure ice VII phase in liquid water using 30 ps laser pulses, demonstrating GPa-level shock compression.
- Reduced Energy Threshold: Utilizing ps pulses, the threshold for ice VII formation was drastically reduced to 3.5 ± 0.5 mJ, over 50 times lower than previously reported nanosecond (ns) laser excitation methods.
- Mechanism Identification: The reduced threshold is attributed to the alignment of the H-bond network and efficient electron-ion energy transfer coinciding with the short pulse duration, supported by plasma shielding and filamentation.
- Localized Extreme Conditions: Filamentation localized the high-pressure shockwaves, creating a sustained ice VII structure over 3-5 mm lengths and 45-57 ”m diameters.
- Advanced Diagnostics: The study relies on Forward Stimulated Raman Scattering (FSRS) and longitudinal imaging, requiring high-purity, low-absorption optical components capable of handling high peak power densities.
- 6CCVD Relevance: This research validates the need for robust, ultra-pure Single Crystal Diamond (SCD) and Polycrystalline Diamond (PCD) optics, which 6CCVD supplies for high-power laser systems and Diamond Anvil Cell (DAC) applications operating under extreme dynamic and static pressures (2-63 GPa).
Technical Specifications
Section titled âTechnical SpecificationsâThe following hard data points were extracted from the experimental results:
| Parameter | Value | Unit | Context |
|---|---|---|---|
| Laser Pulse Duration | 30 | ps | Excitation source |
| Laser Wavelength | 532 | nm | Second harmonic of Nd:YAG |
| Repetition Rate | 10 | Hz | Laser operation frequency |
| Input Energy Range | 190 ”J to 16.2 | mJ | Range of varied input energy |
| Ice VII Formation Threshold | 3.5 ± 0.5 | mJ/pulse | Reduced threshold for phase transition |
| Ice VII Stability Pressure Range | 2 to 63 | GPa | Referenced static stability range |
| Ice VII Raman Shift (A1g mode) | 3050 | cm-1 | Strongest vibrational mode observed |
| Liquid Water Raman Shift (OH) | 3400 | cm-1 | Dominant liquid water mode |
| Saturated Filament Length | 3.5 - 5.1 | mm | Localized high-pressure zone |
| Saturated Filament Diameter | 45 - 57 | ”m | Localized high-pressure zone |
| Rayleigh Length (Zr) | 810 | ”m | Focused beam characteristic in water |
Key Methodologies
Section titled âKey MethodologiesâThe experiment utilized a specialized setup combining high-power laser focusing with advanced spectroscopic detection:
- Laser Source & Conditioning: Dual amplified 30 ps Nd:YAG laser (532 nm, 10 Hz) was used. Input energy was precisely controlled using a Half Wave Plate (HWP) and Brewster Polarizer (BP).
- Focusing Geometry: A 150 mm anti-reflection coated plano-convex lens focused the 12 mm diameter laser beam into a 100x30x30 mm liquid water cuvette.
- Shockwave Generation: Laser energy density at the focal volume was sufficient to cause optical breakdown, generating a plasma plume and subsequent shockwave compression, leading to the formation of ice VII.
- FSRS Signal Collection: Collimated Forward Stimulated Raman Scattering (FSRS) signals were collected from the interaction zone via an optical fiber coupled to a spectrometer (Maya 2000).
- Signal Separation: A Constant Deviation Prism (CDP) and Neutral Density Filters (NDF) were employed to separate the Rayleigh, Stokes, and anti-Stokes satellites and prevent detector saturation.
- Filamentation Analysis: Self-emission and cavitation bubble generation were captured along the longitudinal direction using a CCD camera (SP620U) to visualize the high-pressure filament structure.
6CCVD Solutions & Capabilities
Section titled â6CCVD Solutions & CapabilitiesâThis research demonstrates the critical need for materials that can withstand extreme dynamic loading and offer superior optical transparency for high-power laser diagnostics. 6CCVD is uniquely positioned to supply the necessary MPCVD diamond components to replicate or extend this high-pressure research.
Applicable Materials for High-Pressure Optics
Section titled âApplicable Materials for High-Pressure OpticsâTo ensure minimal absorption, high thermal conductivity, and maximum mechanical stability under GPa-level shock loading, 6CCVD recommends the following materials:
| Material | Recommended Grade | Key Feature & Application | 6CCVD Capability |
|---|---|---|---|
| Single Crystal Diamond (SCD) | Optical Grade (Low N) | Ideal for high-power laser windows, lenses, and beam splitters where Ra < 1 nm polishing is required to minimize scattering and absorption. | Thicknesses from 0.1 ”m up to 500 ”m. |
| Polycrystalline Diamond (PCD) | Optical/Thermal Grade | Suitable for large-area optical components (up to 125 mm diameter) or heat spreaders in the laser system, offering high thermal stability. | Plates/wafers up to 125 mm diameter. Polishing Ra < 5 nm. |
| Boron-Doped Diamond (BDD) | N/A (Electrochemical) | While not used in this optical setup, BDD is available for future extensions involving electrochemical analysis under high pressure. | Custom doping levels and dimensions available. |
Customization Potential for Shock Compression Research
Section titled âCustomization Potential for Shock Compression ResearchâThe precision required for focusing optics and cuvette windows in high-pressure experiments necessitates custom dimensions and finishing. 6CCVD offers comprehensive customization services:
- Custom Dimensions: We provide SCD and PCD plates and wafers in custom sizes, ensuring perfect fit for specialized focusing geometries and high-pressure cells (e.g., Diamond Anvil Cell components).
- Precision Polishing: We guarantee ultra-low surface roughness (Ra < 1 nm for SCD) critical for minimizing laser-induced damage and scattering losses at the 532 nm operating wavelength.
- Metalization Services: Although not explicitly used in this setup, 6CCVD offers in-house metalization (Au, Pt, Pd, Ti, W, Cu) for creating custom electrical contacts or reflective coatings on diamond surfaces, enabling integrated diagnostics.
- Substrate Thickness: We can supply robust diamond substrates up to 10 mm thick for use as high-pressure windows or anvils, capable of withstanding the extreme mechanical stress referenced (2-63 GPa).
Engineering Support
Section titled âEngineering Supportâ6CCVDâs in-house PhD team specializes in the application of MPCVD diamond in extreme environments, including high-power optics and high-pressure physics. We offer consultation on:
- Optimizing material selection (SCD vs. PCD) based on required optical clarity, size, and mechanical load limits.
- Designing custom diamond windows for dynamic shock compression experiments to maximize transmission efficiency and lifetime.
- Integrating metalized diamond components into complex diagnostic setups, such as FSRS systems.
For custom specifications or material consultation, visit 6ccvd.com or contact our engineering team directly. We ship globally (DDU default, DDP available).
View Original Abstract
Water dominantly present in liquid state on earth gets transformed to crystalline polymorphs under different dynamic loading conditions. Out of different crystalline phases discovered till date, ice VII is observed to be stable over wide pressure (2-63 GPa) and temperature (>273 K) ranges. The formation of ice VII crystalline structure has been vastly reported during high pressure static compression using diamond anvil cell and propagation of high energy (>50 mJ/pulse) nanosecond laser pulse induced dynamic high pressures through liquid water. We present the onset of ice VII phase at low threshold of 2 mJ/pulse during 30 ps (532 nm, 10 Hz) laser pulse induced shock propagating through liquid water. Role of input pulse energy on the evolution of Stokeâs and anti-Stokeâs Raman shift of the dominant A1g mode of ice VII, filamentation, free-electrons, plasma shielding is presented. The H-bond network rearrangement, electron ion energy transfer time coinciding with the excitation pulse duration supported by the filamentation and plasma shielding of the ps laser pulses reduced the threshold of ice VII structure formation. Filamentation and the plasma shielding have shown the localized creation and sustenance of ice VII structure in liquid water over 3 mm length and 50 ÎŒm area of cross-section.