Evidence of absorption dominating over scattering in light attenuation by nanodiamonds

Abstract

We show an experimental evidence of the domination of absorption over scattering in absorbance spectra of detonation nanodiamonds. We perform the absorbance measurements on the UV-Vis spectrophotometer equipped with integrating sphere and compare them with conventional absorbance spectra. Additionally, we measure the scattering light intensity at the cuvette side wall (scattering at 90 degrees angle). The obtained experimental data were interpreted using the simulations of photon random walk in turbid media and Kubelka-Munk approach. The scattering cross sections and indicatrices were obtained by Mie theory.We discover that despite being very close to λ −4 power law (like Rayleigh scattering) the light extinction by the primary 4 nm diamond crystallites is due to absorption only and scattering can be neglected. That is the reason why previously absorption and scattering contributions were confused. The scattering is governed only by the agglomerates of 100 nm and larger in size remaining in the hydrosols and their fraction can be effectively controlled by centrifugation. Only Mie theory reproduces correctly the close to λ −2 scattering by the agglomerates accounting for the weird interplay between their size, fractal dimension, and dielectric properties. Finally, using the obtained absorbance spectra we estimate the fraction of non diamond phase in nanodiamonds and their agglomerates. arXiv:1812.03512v2 [cond-mat.mes-hall]

Lifetimes of confined optical phonons and the shape of a Raman peak in disordered nanoparticles. II. Numerical treatment

“…The fourth mechanism which leads to the Raman peak broadening in nanoparticles originates from surface amorphization (see Fig 1d) well-documented for nanodiamonds [25,29,57,58]. It takes place within the nearsurface shell of a crystal due to crystal interference with surrounding media during its growth and/or aging.…”

“…This imposes the strict necessity for tools and methods of their physical and chemical characterization [16,17], the particle size is important parameter to know. Such experimental techniques as atomic force microscopy, dynamic light scattering, transmission electron microscopy, calorimetry, X-rays diffraction, Raman spectroscopy, etc., have been used for these purposes [18][19][20][21][22][23][24][25][26][27][28][29][30].…”

Femtosecond Optical Nonlinearity of Nanodiamond Suspensions

“…In accordance with [56], this is caused by light scattering (the cross-section of which decreases with an increase in the wavelength of incident radiation) and optical absorption that occurs in detonation nanodiamonds in the energy range of 1-2 eV. In a recent paper [69], it was shown that the characteristic extinction spectrum (see Figure 3) of detonation nanodiamonds with a size less than 100 nm is mainly determined by absorption rather than a scattering of light. The saturable absorption we observed in a suspension of detonation nanodiamonds at a photon energy of 1.56 eV is in agreement with these studies.…”

Effects of Bond Disorder and Surface Amorphization on Optical Phonon Lifetimes and Raman Peak Shape in Crystalline Nanoparticles

“…An intermediate and very widespread case is the nanoparticles with crystalline core and amorphous shell (or coating). In this context, it is instructive to mention the nanodiamonds with sp 3 hybridized core carbon atoms and sp 3−x bonded carbon atoms within the amorphous or partly graphitized shell [18][19][20][21][22][23][24][25] . Importantly, the fraction of surface atoms in nanoparticles is comparable with the one of the core.…”

“…of particle cores rather than that of coated particles, so these approaches should be properly modified to account for the coating. On the con-trary, the dynamic light scattering (DLS) and the atomic force microscopy (AFM) provide us with the information about the total nanoparticle size including the surface shell 24,44,45 . The high resolution transmission electron microscopy (HRTEM) is suitable for the insight into atomic structure of particles, albeit it is a strictly local technique 23,25,45,46 .…”