arxiv: 2605.06539 · v1 · submitted 2026-05-07 · ❄️ cond-mat.mtrl-sci · cond-mat.mes-hall

Recognition: unknown

On Fano effect in IR spectra of hydrogenated nanodiamonds

Andrei A. Shiryaev , Evgeni A. Ekimov

Authors on Pith no claims yet

Pith reviewed 2026-05-08 08:38 UTC · model grok-4.3

classification ❄️ cond-mat.mtrl-sci cond-mat.mes-hall

keywords nanodiamondsFano resonanceinfrared spectrasurface hydrogenationmonohydride terminationtransmission windowoptical phononsurface modes

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The pith

C-H stretch vibrations cannot explain the Fano resonance in hydrogenated nanodiamonds; a bending mode of monohydride on (111) faces may couple to the optical phonon instead.

A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.

The paper analyzes infrared spectra from hydrogenated nanodiamonds sized 2.6 to 30 nanometers that display a transmission window near the diamond Raman frequency. This window arises from Fano resonance through resonant coupling of photons to continuum states. The detailed comparison across particle sizes shows that stretch vibrations from adsorbed C-H functional groups cannot produce the resonance. The authors instead propose that bending vibrations of monohydride terminations on the (111) crystal faces can couple with the diamond optical phonon to generate the effect under suitable conditions. Whether this monohydride mechanism or graphitic surface features dominate depends on the grains' overall morphology and size distribution.

Core claim

Detailed analysis of IR spectra of nanodiamonds of different sizes (2.6-30 nm) possessing the transmission window shows that the C-H stretch vibrations of adsorbed functional groups cannot be responsible for the Fano resonance. At the same time, it is suggested that a bending mode of monohydride termination on nanodiamond (111) face may couple with diamond optical phonon, explaining the Fano resonance in some cases. The relative importance of the monohydride contribution and of the graphitic islets to the appearance of the transmission window and conductivity is likely dependent on dominating morphology and size distribution of nanodiamond grains.

What carries the argument

Coupling of the bending vibration mode of monohydride termination on the (111) nanodiamond face with the diamond optical phonon, enabling photon interaction with continuum states to produce the observed Fano resonance and transmission window.

If this is right

Surface C-H stretch vibrations of adsorbed groups do not drive the resonance or associated conductivity.
Monohydride terminations specifically on (111) faces can account for the Fano resonance when those faces predominate.
Graphitic islets on the surface compete with the monohydride mechanism depending on particle shape.
The strength and presence of the transmission window vary systematically with nanodiamond size and morphology.

Where Pith is reading between the lines

These are editorial extensions of the paper, not claims the author makes directly.

Engineering nanodiamond surfaces to favor monohydride coverage on (111) facets could allow deliberate tuning of their infrared transmission and conductivity.
Analogous bending-mode couplings to optical phonons may occur in other faceted nanoparticles and warrant targeted checks.
Facet-selective spectroscopy on individual grains would provide a direct test of the proposed monohydride contribution.

Load-bearing premise

The transmission window is a genuine Fano resonance from photon coupling to continuum states, and size and morphology differences in the samples can isolate the contribution of particular surface terminations without major interference from other reconstructions or impurities.

What would settle it

IR spectra recorded on nanodiamond samples with controlled (111)-facet dominance and verified monohydride termination, compared against samples lacking such terminations, would show whether the transmission window appears or disappears as predicted.

Figures

Figures reproduced from arXiv: 2605.06539 by Andrei A. Shiryaev, Evgeni A. Ekimov.

**Figure 1.** Figure 1: b shows that in the small nanodiamonds with sizes ~2.6-3.4 nm the Fanorelated range possess complex structure with several bands. For the larger grains (8 and 30 nm) the absorption dip is markedly asymmetric with a tail towards smaller wavenumbers; thus qualitatively resembling diamond Raman peak of nanodiamonds (e.g., [8]). For the smallest nanodiamonds the Fano region contains at least three components … view at source ↗

**Figure 2.** Figure 2: Integrated area of the Fano- and C-H-related bands. Both the Fano-related and C-H regions are rather complex and comprise numerous bands. We analyse behavior of several components obtained from the decomposition of the spectral envelope of C-H region and centered at ~2816, 2825-2837, 2847-2857, 2892-2895, 2915-2923, 2957 cm-1 . These bands are present in all spectra; position of maxima may be sample-depend… view at source ↗

**Figure 3.** Figure 3: Amplitude of the Fano-related infra-red “transmission window” as function of several prominent C-H bands, see text for details. The numbers indicate size of nanodiamond grains. The lines are to guide an eye. The inset shows behavior of the 2816 cm-1 band. Discussion Whereas hydrogenation definitely plays important role in surface conductivity of macro- and nanodiamond [15, 16], the present study shows that… view at source ↗

**Figure 4.** Figure 4: Amplitude of the 2825-2837 cm-1 band as a function of the modulus of absorption of a component peaking at 1322-1329 cm-1 . The numbers indicate size of nanodiamond grains view at source ↗

**Figure 5.** Figure 5: Zoomed region of IR spectra showing possible correspondence between view at source ↗

read the original abstract

Hydrogenated nanodiamonds may show a "transmission window" in infra-red spectra in the vicinity of diamond Raman frequency. This phenomenon is a manifestation of resonance coupling of incident photons with continuum states (Fano resonance). Hpwever, precise mechanism of appearence of the resonance and of related conductivity - surface hydrogenation or specific type of surface reconstruction - remains debatable. We present detailed analysis of infra-red spectra of nanodiamonds of different sizes (2.6-30 nm) possessing the "transmission window" and show that the C-H stretch vibrations of adsorbed functional groups cannot be responsible the the Fano resonance. At the same time, it is suggested that a bending mode of monohydride termination on nanodiamond (111) face may couple with diamond optical phonon, explaining the Fano resonance in some cases. The relative importance of the monohydride contribution and of the graphitic islets to the appearence of the "transmission window" and conductivity is likely dependent on dominating morphology and size distribution of nanodiamond grains.

Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, simulated authors' rebuttal, and a circularity audit. Tearing a paper down is the easy half of reading it; the pith above is the substance, this is the friction.

Desk Editor's Note private letter to a colleague

Size-dependent spectra rule out C-H stretches as the Fano cause and point to (111) monohydride bending, but the assignment still rests on correlations that may not isolate that mode cleanly.

read the letter

The main point is that the authors compare IR spectra across hydrogenated nanodiamonds from 2.6 to 30 nm and conclude that C-H stretch modes from adsorbed groups cannot explain the transmission window near the diamond optical phonon. They instead propose that a bending mode from monohydride termination on (111) faces couples to the phonon continuum in at least some cases, with graphitic islets possibly contributing depending on morphology and size distribution. This is a concrete mechanistic step beyond earlier observations of the window itself. The size series is a reasonable way to test surface-related effects, and the paper is careful to note that the relative weight of the two contributions likely varies with grain shape and distribution. That keeps the claim from overreaching. The soft spot is that particle size and implied morphology changes do not automatically isolate the monohydride bending contribution. Other surface features—graphitic patches, different reconstructions, or impurities—could shift in tandem and still produce the observed correlation. Without quantitative surface coverage data or independent checks that hold those variables fixed, the bending-mode assignment remains a plausible suggestion rather than a strongly pinned result. The abstract already flags the morphology dependence, which is honest but also shows where the evidence is thinnest. This is niche work aimed at researchers who characterize or engineer hydrogenated nanodiamond surfaces for optical or electronic uses. A reader already following the Fano-window literature will pick up the new size trend and the specific mode proposal. It is coherent on its own terms and engages the existing citations, so it deserves a serious referee. I would send it for review and expect the main questions to focus on how well the surface terminations were controlled and whether the bending-mode coupling is demonstrated or just hypothesized.

Referee Report

1 major / 2 minor

Summary. The manuscript analyzes infrared spectra of hydrogenated nanodiamonds (sizes 2.6–30 nm) exhibiting a transmission window near the diamond optical phonon frequency (~1332 cm⁻¹), interpreted as a Fano resonance arising from photon coupling to continuum states. The authors rule out C-H stretch vibrations of adsorbed functional groups as the origin based on size-dependent spectral comparisons and propose that a bending mode of monohydride termination on the (111) face may couple to the phonon continuum to produce the feature in some cases, with relative importance of this mode versus graphitic islets depending on morphology and size distribution.

Significance. If substantiated, the work would help resolve debates on the microscopic origin of Fano resonances and associated conductivity in hydrogenated nanodiamonds by linking specific surface terminations to the observed spectral feature. This could inform surface engineering for nanodiamond applications in electronics and sensing, while highlighting how particle size and facet distribution modulate vibrational coupling.

major comments (1)

The load-bearing claim that size and implied morphology variations (2.6–30 nm) cleanly isolate the contribution of the (111) monohydride bending mode—while holding constant or independently quantifying other surface states such as graphitic islets, reconstructions, or impurities—is not supported by quantitative surface analysis or controls. Without such data, the observed correlation between window presence and particle size cannot be uniquely attributed to the proposed bending mode (see skeptic concern on confounding factors).

minor comments (2)

Abstract: Multiple typos and grammatical issues ('Hpwever' → 'However'; 'responsible the the Fano' → 'responsible for the Fano'; 'appearence' → 'appearance', twice) detract from clarity.
Abstract: The statement that 'detailed analysis' rules out C-H stretches would benefit from explicit reference to the specific spectral features or quantitative metrics (e.g., intensity ratios or peak positions) used in the comparison across sizes.

Simulated Author's Rebuttal

1 responses · 0 unresolved

We thank the referee for the constructive and detailed review of our manuscript. We address the major comment point by point below, providing the strongest honest defense of our analysis while acknowledging its limitations.

read point-by-point responses

Referee: The load-bearing claim that size and implied morphology variations (2.6–30 nm) cleanly isolate the contribution of the (111) monohydride bending mode—while holding constant or independently quantifying other surface states such as graphitic islets, reconstructions, or impurities—is not supported by quantitative surface analysis or controls. Without such data, the observed correlation between window presence and particle size cannot be uniquely attributed to the proposed bending mode (see skeptic concern on confounding factors).

Authors: We do not claim that particle size variations alone provide a clean, quantitative isolation of the (111) monohydride bending mode while holding all other surface states constant. Our central result is the exclusion of C-H stretch vibrations from adsorbed functional groups as the origin of the transmission window, based on direct spectral comparisons across the 2.6–30 nm range that show no matching intensity or position trends. The suggestion that monohydride bending on (111) faces can couple to the optical phonon continuum is offered as a plausible mechanism consistent with known vibrational frequencies and the observed Fano lineshape in smaller particles, which literature indicates possess higher (111) facet fractions. We agree that independent quantification of graphitic islets, reconstructions, or impurities (e.g., via XPS or detailed Raman deconvolution) is absent and would strengthen attribution. In the revised manuscript we will add an explicit limitations paragraph discussing potential confounding factors, the correlative nature of the size-dependent evidence, and the morphology-dependent balance between monohydride and graphitic contributions, without overstating uniqueness. revision: partial

Circularity Check

0 steps flagged

No significant circularity; experimental spectral comparisons stand independently

full rationale

The paper's central claims rest on direct experimental comparison of IR spectra across nanodiamond samples of sizes 2.6–30 nm that exhibit or lack the transmission window. It rules out C-H stretch modes of adsorbed groups by observing that the window persists or varies independently of those modes, then proposes a possible coupling of (111) monohydride bending vibration to the optical phonon continuum. No equations, fitted parameters, or self-citations are invoked to derive the attribution; the reasoning is observational and does not reduce any prediction to its own inputs by construction. The derivation chain is therefore self-contained against external spectral data.

Axiom & Free-Parameter Ledger

0 free parameters · 1 axioms · 0 invented entities

The work is an experimental spectral study that relies on standard domain assumptions about Fano resonance interpretation and surface chemistry of nanodiamonds; no free parameters, invented entities, or non-standard axioms are introduced in the abstract.

axioms (1)

domain assumption The observed transmission window is a manifestation of Fano resonance arising from resonance coupling of incident photons with continuum states.
Explicitly stated in the abstract as the underlying phenomenon being analyzed.

pith-pipeline@v0.9.0 · 5487 in / 1343 out tokens · 45490 ms · 2026-05-08T08:38:14.794224+00:00 · methodology

discussion (0)

Reference graph

Works this paper leans on

23 extracted references · 7 canonical work pages

[1]

Ekimov, A.A

E. Ekimov, A.A. Shiryaev, Y. Grigoriev, A. Averin, E. Shagieva, S. Stehlik and M. Kondrin. Size -Dependent Thermal Stability and Optical Properties of Ultra -Small Nanodiamonds Synthesized under High Pressure, Nanomaterials (2022), 12(3), 351, https://www.mdpi.com/2079-4991/12/3/351/pdf

2022
[2]

Kudryavtsev, R.H

O.S. Kudryavtsev, R.H. Bagramov, A.M. Satanin, A.A. Shiryaev, O.I. Lebedev, A.M. Romshin, D.G. Pasternak, A.V. Nikolaev, V.P. Filonenko, and I.I. Vlasov. Fano -type Effect in Hydrogen -Terminated Pure Nanodiamond, Nano Letters (2022), 22, 2589−2594 , https://doi.org/10.1021/acs.nanolett.1c04887

work page doi:10.1021/acs.nanolett.1c04887 2022
[3]

A. A. Shiryaev, E. A. Ekimov, V. Yu. Prokof’ev, and M. V. Kondrin. Temperature Dependence of the Fano Resonance in Nanodiamonds Syn thesized at High Static Pressures, JETP Letters (2022), 115(11), 651–656

2022
[4]

Ekimov, S

E. Ekimov, S. Lyapin, Y. Grigoriev, I. Zibrov, K. Kondrina. Size-controllable synthesis of ultrasmall diamonds from halogenated adamantanes at high static pressure. Carbon (2019), 150, 436–438

2019
[5]

J. W. Ager III, W. Walukiewicz, M. McCluskey, M. A. Plano, M. I. Landstrass. Fano interference of the Raman phonon in heavily boron -doped diamond films grown by chemical vapor deposition. Applied Physics Letters (1995), 66, 616; doi: 10.1063/1.114031

work page doi:10.1063/1.114031 1995
[6]

Ekimov, A.A

E.A. Ekimov, A.A. Shiryaev, T.B. Shatalova, K.I. Maslakov, S.G. Lyapin, K.M. Kondrina, Y.V. Grigoriev, S. Stehlik, M.V. Kondrin. Thermal stability and oxidation resistance of single -digit boron -doped nanodiamonds, Materials Research Bull etin (2025), 192, 113604

2025
[7]

H. Y. Fan. Effects of Free Carriers on the Optical Properties. Semiconductors and semimetals (1967), 3, 405-419

1967
[8]

Osswald, V

S. Osswald, V. N. Mochalin, M. Havel, G. Yushin, Y. Gogotsi. Phonon confinement effects in the Raman spectrum of nanodiamond. Physical review B (2009), 80, 075419

2009
[9]

M. Wojdyr. Fityk: a general -purpose peak fitting program. J. Appl. Cryst. (2010) 43, 1126-1128

2010
[10]

Chang, J

H.-C. Chang, J. -C. Lin; J. -Y. Wu, K. -H. Chen. Infrared Spectroscopy and Vibrational Relaxation of CH, and CD, Stretches on Synthetic Diamond Nanocrystal Surfaces, J. Phys. Chem. (1995), 99, 11081-11088

1995
[11]

C. -L. Cheng, J. -C. Lin, and H. -C. Chang . The absolute absorption strength and vibrational coupling of CH stretching on diamond C(111), The Journa l of Chemical Physics (1997), 106, 7411; doi: 10.1063/1.473701

work page doi:10.1063/1.473701 1997
[12]

J.-C. Lin, K. -H. Chen, H. -C. Chang, C. -S. Tsai, C. -E. Lin, and J. -K. Wang . The vibrational dephasing and relaxation of CH and CD stretches on diamond surfaces: An anomaly, J. Chem. Phys. (1996), 105, 3975

1996
[13]

S.-Y. Sheu, I. -P. Lee, Y. T. Lee, and H. -C. Chang . Laboratory investigation of hydrogenated diamond surfaces: implications for the formation and size of interstellar nanodiamonds, The Astrophysical Journal (2002), 581, L55–L58

2002
[14]

A. E. Klingbeil, J. B. Jeffries, R. K. Hanson . Temperature-dependent mid-IR absorption spectra of gaseous hydrocarbons. Journal of Quantitative Spectroscopy & Radiative Transfer (2007), 107 407–420,

2007
[15]

Maier, M

F. Maier, M. Riedel, B. Mantel, J. Ristein, L. Ley. Origin of surface conductivity in diamond. Phys. Rev. Lett. (2000), 85, 3472−3475

2000
[16]

Bolker, C

A. Bolker, C. Saguy, R. Kalish. Transfer doping of single isolated nanodiamonds, studied by scanning probe microscopy techniques. Nanotechnology (2014), 25, 385702

2014
[17]

J. L. Birman . Theory of Crystal Space Groups and Infra -Red and R aman Lattice Processes of Insulating Crystals. In : Theory of Crystal Space Groups and Lattice Dynamics, 1–521. Berlin, Heidelberg: Springer. (1974) https://doi.org/10.1007/978-3-642-69707-4_1

work page doi:10.1007/978-3-642-69707-4_1 1974
[18]

Brand, G

J.C.D. Brand, G. Eglington. Applications of spectroscopy to organic che mistry. Oldbourne press, London (1965)

1965
[19]

Brown, A.J

D.W. Brown, A.J. Floyd, M. Sainsbury. Organic spectroscopy. Wiley. (1988)

1988
[20]

J.-S. Tu, E. Perevedentseva, P. -H. Chung, and C. -L. Cheng. Size-dependent surface CO stretching frequency investigations on nanodiamond particles, J. Chem. Phys. (2006), 125, 174713; doi: 10.1063/1.2370880

work page doi:10.1063/1.2370880 2006
[21]

R. P. Chin, J. Y. Huang, and Y. R. Shen, T. J. Chuang, H. Seki . Interaction of atomic hydrogen with the diamond C(111)surface studied by infrared -visible sum -frequency- generation spectroscopy. Physical Review B (1995), 52(8), 5985-5995

1995
[22]

Allouche, Y

A. Allouche, Y. Ferro, T. Angot, C. Thomas, J. -M. Layet . Hydrogen adsorption on graphite (0001) surface: A combined s pectroscopy–density-functional-theory study. J. Chem. Phys. (2005), 123, 124701; doi: 10.1063/1.2043008

work page doi:10.1063/1.2043008 2005
[23]

Shiryaev, V.B

A.A. Shiryaev, V.B. Polyakov, S. Rols, A. Rivera, O.A. Shenderova. Inelastic neutron scattering: A novel approach towards determination of equilib rium isotopic fractionation factors. Size effects on heat capacity and beta -factor of diamond , Physical Chemistry Chemical Physics (2020), 22, 13261 – 13270, DOI: 10.1039/D0CP02032J

work page doi:10.1039/d0cp02032j 2020