Communication: Three-dimensional model for phonon confinement in small particles: Quantitative bandshape analysis of size-dependent Raman spectra of nanodiamonds

Korepanov, Vitaly I.; Witek, Henryk A.; Okajima, Hajime; Ōsawa, Eiji; Hamaguchi, Hiro‐o

doi:10.1063/1.4864120

Cited by 28 publications

(32 citation statements)

References 26 publications

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“…Our results thus indicate that the shift to lower wavenumbers and asymmetric broadening of the DND diamond peak in comparison to bulk diamond may actually corresponds to 2 nm or even smaller single crystal diamond core or a scattering domain41 either in form of a monolithic DNDs or ~2 nm crystallites within the DNDs. This is in agreement with the finding that the shift and broadening of the Raman diamond peak regularly observed for DNDs do not correspond to the phonon confinement in 5 nm diamond nanocrystals as the HPHT NDs of similar size exhibited a much smaller shift and broadening3.…”

Section: Resultsmentioning

confidence: 70%

High-yield fabrication and properties of 1.4 nm nanodiamonds with narrow size distribution

Stehlík

Varga

Ledinský

et al. 2016

Sci Rep

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Detonation nanodiamonds (DNDs) with a typical size of 5 nm have attracted broad interest in science and technology. Further size reduction of DNDs would bring these nanoparticles to the molecular-size level and open new prospects for research and applications in various fields, ranging from quantum physics to biomedicine. Here we show a controllable size reduction of the DND mean size down to 1.4 nm without significant particle loss and with additional disintegration of DND core agglutinates by air annealing, leading to a significantly narrowed size distribution (±0.7 nm). This process is scalable to large quantities. Such molecular-sized DNDs keep their diamond structure and characteristic DND features as shown by Raman spectroscopy, infrared spectroscopy, STEM and EELS. The size of 1 nm is identified as a limit, below which the DNDs become amorphous.

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Section: Resultsmentioning

confidence: 70%

High-yield fabrication and properties of 1.4 nm nanodiamonds with narrow size distribution

Stehlík

Varga

Ledinský

et al. 2016

Sci Rep

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show abstract

“…For this reason, it is necessary to take into account the particle size distribution. This makes the working formula: where ρ(σ) is the particle size distribution and N(σ) is the normalizing factor (the area under the spectral shape for the given size σ) [18] . The integration over q is not limited to the BZ, because the lattice periodicity is broken [17] .…”

Section: Figmentioning

confidence: 99%

Quantum‐chemical perspective of nanoscale Raman spectroscopy with the three‐dimensional phonon confinement model

Korepanov

Hamaguchi

2017

J Raman Spectroscopy

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Raman spectroscopy of crystalline/molecular systems is well backed with quantum chemical calculations and group theory, making it a unique characterization tool. For the "intermediate" case of nanoscale systems, however, the use of Raman spectroscopy is limited by the lack of such theoretical bases. Here, we suggest to couple a scaled quantum-mechanical (SQM) calculation with the phonon confinement model (PCM) to construct a universal and physically consistent basis for nanoscale Raman spectroscopy. Unlike the commonly used one-dimensional dispersion PCM, we take into account the confinement along all the three dimensions of the k-space. We apply it to diamond nanoparticles of sub-50nm size, a system with pronounced anisotropy of dispersion for which the use of three-dimensional dispersion is a requisite. The model excellently reproduces sizesensitive spectral features, including the peak position, bandwidth and asymmetry of the sp 3 C-C Raman band. This fundamental approach can be easily generalized to other nanocrystalline solids to hopefully contribute the future development of quantitative nanoscale Raman spectroscopy. Keywords: phonon confinement, nanoparticlesThe continuously growing interest to nanoscale matter drives a strong demand for fast, noninvasive and statistically reliable characterization methods. This makes Raman spectroscopy an indispensable tool for nanoscience. The difficult challenge of Raman spectroscopy of nanoscale materials is to establish a consistent way to link the Raman pattern to the characteristic size of the crystallites. The straightforward approach is to directly calculate the normal modes of nanoparticles as big molecules [1,2] . This requires assumptions of the shape, size and symmetry. The calculated spectra are the set of narrow lines. Since the number of normal modes for nanoparticles is in the order of thousands, such calculations do not seem to be routinely availbale for real systems. The other common approach is the elastic sphere model (ESM), in which the nanoparticle is approximated by a homogeneous isotropic freestanding elastic sphere. The vibrations of such system can be easily derived from first principles calculations [3] . For the nanoparticles of other shapes, as well as systems with the size smaller than ~5nm, the applicability of ESM is limited. For more details on ESM the reader is referred to the review [4] . The third general approach starts from the Raman spectrum of a bulk crystal, for which the selection rules allow only the phonons close to the Brillouin zone (BZ) center. Nano-size crystallites lack the translational symmetry and the quasimomentum preservation does not hold. As a result, BZ points away from the center can also contribute to the Raman spectra. To what extent the selection rule breaks depends on the size of the crystallite. This effect is named the "phonon confinement" after the work of Richter [5] , who first suggested the physical model for describing it. The approach by Richter's is to multiply the phonon wavefunction of the crystal φ...

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“…This result suggests that the size of sp 3 ‐bonded tetrahedral clusters in the DLC films is independent of post‐annealing temperature. This position is far from the position of a diamond crystal (1332 cm −1 ), demonstrating that the clusters are very small . The D′ band is fixed at 1618 cm −1 (also not shown).…”

Section: Resultsmentioning

confidence: 85%

“…The average size of aromatic aggregate constituents or clusters is evaluated by the D band position. High position indicates large cluster size . Aromatic sp 2 carbon constituents are dominant in the as‐prepared DLC film made from benzene, and the size increases during high‐temperature post‐annealing.…”

Section: Resultsmentioning

confidence: 99%

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Influence of post‐annealing on a diamondlike carbon film analyzed by Raman spectroscopy

Takabayashi

Okamoto

Nakatani

2018

Surface & Interface Analysis

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The influence of a post‐annealing treatment on the chemical structure of a diamondlike carbon (DLC) film was clarified by Raman spectroscopy. The DLC films were synthesized by ionized deposition. The structures were elucidated via Raman analysis in conjunction with the sp2 cluster model. The as‐prepared DLC film consisted of a dielectric matrix including sp3 carbon, where sp2 clusters were floating. When the post‐annealing treatment commenced, especially between 450 and 600°C, carbon─hydrogen bonds were cleaved, and the hydrogen atoms were desorbed from the film, creating defects or dangling bonds. The defects were reactive in growing sp2 clusters that were strained with numerous defects because of the restricted degrees of freedom in the solid. As the post‐annealing temperature further increased, the clusters became dominant and the strain was gradually dissolved.

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Communication: Three-dimensional model for phonon confinement in small particles: Quantitative bandshape analysis of size-dependent Raman spectra of nanodiamonds

Cited by 28 publications

References 26 publications

High-yield fabrication and properties of 1.4 nm nanodiamonds with narrow size distribution

High-yield fabrication and properties of 1.4 nm nanodiamonds with narrow size distribution

Quantum‐chemical perspective of nanoscale Raman spectroscopy with the three‐dimensional phonon confinement model

Influence of post‐annealing on a diamondlike carbon film analyzed by Raman spectroscopy

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