Effects of bond disorder and surface amorphization on optical phonon lifetimes and Raman peak shape in crystalline nanoparticles

Abstract

Optical phonons in nanoparticles with the randomness of interatomic bonds are considered both analytically and numerically. For weak dilute disorder two qualitatively different regimes of separated and overlapped levels are observed, resembling the case of random atomic masses investigated previously. At stronger and/or more dense disorder, the particles become essentially inhomogeneous, thus constituting the minimal model to describe an amorphous phase, where the picture of vibrational modes becomes more subtle. We concentrate here on the experimentally relevant case of strong disorder located near the particle surface and formulate the core-shell model aimed to describe the ubiquitous phenomenon of particle surface amorphization. We observe a peculiar effect of volume optical phonons "repelling" from the disordered shell. It results in the Raman spectrum in the form of a combination of narrow well-resolved peaks stemming from the quantized modes of a pure particle core (red-shifted due to its effective smaller size), and the noisy background signal from the disordered shell placed primarily to the right from the main Raman peak.

arXiv comment11 pages, 10 figures

References in corpus (13)

• Photoluminescent diamond nanoparticles for cell labeling: study of the uptake mechanism in mammalian cells
• Deterministic enhancement of coherent photon generation from a nitrogen-vacancy center in ultrapure diamond
• Hybrid nanodiamond-YIG systems for efficient quantum information processing and nanoscale sensing
• The Ioffe-Regel criterion and diffusion of vibrations in random lattices
• New explanation of Raman peak redshift in nanoparticles
• Novel approach to Raman spectra of nanoparticles
• Quantum-chemical perspective of nanoscale Raman spectroscopy with three-dimensional phonon confinement model
• A random matrix approach to the boson peak and Ioffe-Regel criterion in amorphous solids
• Raman spectra of nanoparticles: elasticity theory-like approach for optical phonons
• Evidence of absorption dominating over scattering in light attenuation by nanodiamonds
• Lifetimes of Confined Optical Phonons and the Shape of a Raman Peak in Disordered Nanoparticles: I. Analytical Treatment
• Lifetimes of Confined Optical Phonons and the Shape of a Raman Peak in Disordered Nanoparticles: II. Numerical Treatment
• Self-consistent T-matrix approach to gap renormalization in quantum magnets with bond disorder

Cited by in corpus (3)

• Raman peak shift and broadening in crystalline nanoparticles with lattice impurities
• Coupled oscillators model for hybridized optical phonon modes in contacting nanosized particles and quantum dot molecules
• Bench tests for microscopic theory of Raman scattering in powders of disordered nonpolar crystals: nanodiamonds and Si nanoparticles