Raman scattering study on structural and dynamical features of noncrystalline selenium

Area of Science:

• Condensed Matter Physics
• Materials Science
• Spectroscopy

Background:

• Understanding the structure of glassy and supercooled selenium is crucial for materials science.
• Selenium exhibits complex structural dynamics involving rings and chains.

Purpose of the Study:

• To perform a detailed, temperature-dependent Raman scattering study on glassy and supercooled selenium.
• To analyze the ring-chain equilibrium and structural order as a function of temperature.

Main Methods:

• Off-resonant Raman scattering measurements were conducted over a temperature range of 143-353 K.
• Raman spectra were analyzed in three distinct frequency regions: bond-stretching, medium-range order, and low-frequency excitations.
• The study focused on vibrational modes, quasielastic scattering, and the Boson peak.

Main Results:

• The polymer content in selenium was found to exceed 85% near the glass transition temperature, with minimal temperature dependence.
• Analysis clarified the role of ring and chain fragments in the overall polymeric structure.
• The temperature evolution of the Boson peak and the Raman coupling coefficient were determined.

Conclusions:

• Selenium maintains a predominantly polymeric structure across a broad temperature range.
• The study provides insights into the interplay between different structural units and their vibrational behavior.
• The findings contribute to understanding the fundamental properties of amorphous selenium.