Onset of ice VII phase during ps laser pulse propagation through liquid water

• Main Authors: Kumar, V. Rakesh, Kiran, P. Prem
• Format: Conference Proceeding
• Language: English
• Subjects: Crystal structure; Crystallinity; Diamond anvil cells; Diamonds; Energy transfer; Ice formation; Lasers; Pulse duration; Pulse propagation; Shielding; Water
• ISSN: 0094-243X; 1551-7616
• DOI: 10.1063/1.4971620

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 Stoke’s and anti-Stoke’s 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 μm area of cross-section.