Spectroscopy at very high pressures. 14: Laser Raman scattering in ultrasmall samples in a diamond anvil cell

Area of Science:

• Spectroscopy
• Materials Science
• Geophysics

Background:

• Diamond anvil cells (DACs) are crucial for high-pressure research.
• Obtaining high-quality Raman spectra from DACs presents significant challenges.
• Efficient light collection is vital for accurate spectral analysis.

Purpose of the Study:

• To address challenges in high-pressure Raman spectroscopy using DACs.
• To demonstrate a novel optical configuration for improved spectral collection.
• To analyze the vibrational properties of ices under high pressure.

Main Methods:

• Utilized a 90-degree off-axis ellipsoidal mirror for Raman signal collection.
• Employed both 0-degree and 180-degree scattering geometries.
• Acquired Raman spectra of various ice phases (VI, VII, VIII).

Main Results:

• Successfully collected Raman spectra at high pressures using the novel mirror setup.
• Demonstrated the efficacy of the ellipsoidal mirror in both scattering modes.
• Obtained detailed nu(OH) vibrational spectra for ices VI, VII, and VIII.

Conclusions:

• The 90-degree off-axis ellipsoidal mirror is an effective tool for high-pressure Raman spectroscopy.
• This technique enhances spectral collection efficiency in DAC experiments.
• Provides valuable insights into the behavior of water ice under extreme pressures.