Near-forward/high-pressure-backward Raman study of Zn1 − x
 
Be
 x
 
Se (x
 ~ 0.5) - evidence for percolation behavior of the long (Zn―Se) bond

Dicko, H.; Pagès, O.; Hussein, R. Hajj; Pradhan, Gopal K.; Narayana, Chandrabhas; Firszt, F.; Marasek, A.; Paszkowicz, W.; Maillard, A.; Jobard, Céline; Broch, Laurent; Hassan, Fausiya

doi:10.1002/jrs.4817

Cited by 5 publications

(5 citation statements)

References 43 publications

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“…Dicko and co‐workers carried out a near‐forward/high‐pressure‐backward Raman study of Zn 1‐x Be x Se (x ∼ 0.5) to provide evidence for the percolation behaviour of the long Zn‐Se bondlength. Somewhat surprisingly, this study reveals that the phonon‐polariton in question is a “fractional” one in that it carries only half of the available Zn‐Se oscillator strength, as ideally expected in case of a BeSe‐like bimodal Raman behaviour of the long Zn‐Se bond . Mendonca et al studied pressure‐induced structural transformations in In 2‐x Y x (MoO 4 ) 3 systems.…”

Section: High Pressure and Temperature Studiessupporting

confidence: 51%

Recent advances in linear and non‐linear Raman spectroscopy. Part XI

Nafie

2017

J Raman Spectroscopy

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This review, published annually, provides an overview of advances in the field of Raman spectroscopy as found in papers published in the preceding calendar year in the Journal of Raman Spectroscopy (JRS), as well as in trends over the past decade across journals that have published papers important to the field of Raman spectroscopy. This information is obtained from statistical data on article counts obtained from Clarivate Analytics' Web of Science Core Collection by year and by subfield of Raman spectroscopy. Additional information is gleaned from presentations at the IX International Conference on Advanced Vibrational Spectroscopy (ICAVS‐9) in Victoria, British Columbia, Canada, in June 2017 and those featuring Raman scattering at SCIX 2017 organized by the Federation of Analytical Chemistry and Spectroscopy Societies (FACSS) in Reno, Nevada, USA, in October 2017. Coverage is also provided for topics from the European Conference on Non‐linear Optical Spectroscopy (ECONOS 2017) held in April 2017 in Jena, Germany, and the Ninth Congress on the Application of Raman in Art and Archaeology (RAA 2017) in October 2017 in Evora, Portugal. Finally, papers published in JRS in 2016 are highlighted and arranged by topics at the frontier of Raman spectroscopy. Based on this survey information, it is clear that Raman spectroscopy maintains a rapidly expanding influence across a wide range of novel disciplines and applications that provide sensitive photonic information of matter at the molecular level.

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Section: High Pressure and Temperature Studiessupporting

confidence: 51%

Recent advances in linear and non‐linear Raman spectroscopy. Part XI

Nafie

2017

J Raman Spectroscopy

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“…The purely-mechanical TO's are flanked on their high frequency side, i.e. around 240 cm -1 , 430 cm -1 (not observed 14 ), 525 cm -1 , by their ‫ܱܮ(‬ ିௌ , ‫ܱܮ‬ ିௌ ି , ‫ܱܮ‬ ିௌ ା ) counterparts. These LO "shadows" are theoretically forbidden, but activated as minor peaks due to a disorder-induced breaking of the wave vector conservation law, a common feature in mixed crystals.…”

Section: Raman Selection Rules In the Near-forward Scattering Geometrymentioning

confidence: 97%

“…The available BeSe-like oscillator strength further shares between the latter two in proportion to the fractions of the corresponding Be-like (x) and Zn-like (1-x) environments. 14 The related Faust-Henry coefficients scale accordingly. With this, the Raman intensities of the two BeSe-like purelymechanical TO modes of Zn 0.47 Be 0.53 Se and Zn 0.67 Be 0.33 Se, noted ܱܶ ିௌ and ܱܶ ିௌ hereafter, are expected to scale roughly in the ratios 1:1 and 1:2, respectively, as actually observed in their reference Raman spectra taken in the backscattering geometry (see below).…”

Section: Theoretical Insightmentioning

confidence: 99%

“…Parent-related input parameters are also needed, in reference to the (ߝ ∞ , ‫,ܥ‬ ߱ ் , ߱ ) values, corresponding to (5.75, -0.7, 205 cm -1 , 254.5 cm -1 ) for ZnSe and (5.32, -0.7, 450 cm -1 , 501 cm -1 ) for BeSe. 14 By solving numerically the characteristic dispersion of a TO mode (a PP one as well as the corresponding purely-mechanical TO one), as derived from Maxwell's equations, namely ߝ (߱, ‫)ݔ‬ = ‫ݍ‬ ଶ × ܿ ଶ × ߱ ିଶ , which leads to the divergence of the term within brackets in Eq. 1, one accesses the theoretical '߱ vs. ‫'ݍ‬ PP dispersion of the considered Zn 1-x Be x Se mixed crystal.…”

Section: Theoretical Insightmentioning

confidence: 99%

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Near-forward Raman selection rules for the phonon-polariton in (Zn, Be)Se alloys

Dicko

Pagès

Firszt

et al. 2016

Journal of Applied Physics

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The Raman selection rules of the (Zn-Se,Be-Se)-mixed phonon-polariton (PP) created by "alloying" in the three-mode [1x(-Zn-Se),2x(Be-Se)] Zn 1-x Be x Se system, whose dramatic S-like dispersion (∼200 cm -1 ) covers the large frequency gap between the Zn-Se and Be-Se spectral ranges, is studied in its wave vector ‫)ݍ(‬ dependence by near-forward scattering. Both the collapse regime away from Γ and the reinforcement regime near Γ are addressed, using appropriate laser lines and Be contents. We find that in both regimes the considered PP, in fact a transverse mode with mixed mechanical-electrical character, obeys the same nominal Raman selection rules as its purelymechanical (PM) variant commonly observed in the backscattering geometry. Besides, marked differences in the PP Raman lineshapes in the two regimes give a hint about how the PP-like electrical field ‫ܧ‬ ሬԦ develops while descending the S-like dispersion towards Γ. In the reinforcement regime ‫ܧ‬ ሬԦ is large, leading to intra-mode on top of inter-mode ‫ܧ‬ ሬԦ −mediated transfers of oscillator strength between the two Be-Se modes, that both exhibit a fine structure on account of the alloy disorder. In contrast, in the collapse regime ‫ܧ‬ ሬԦ remains weak, as testified by the absence of intramode transfer. The discussion is supported by contour modeling of the multi-PP Raman lineshapes in their ‫-ݍ‬dependence within the linear dielectric approach.

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“…In recent years, the dispersion of the phonon-polaritons propagating in the bulk of several A 1−x B x C mixed crystals has been studied theoretically by Bao and Liang, assuming a crude two-mode [1 × (A-C), 1 × (B-C)] MREI-like TO description [28,29]. On the experimental side we are only aware of the pioneering study of the surface phonon-polariton of the one-mode Al 1−x Ga x N mixed crystal with wurtzite structure done by Ng et al [30] using farinfrared attenuated total reflectance, and of our recent nearforward Raman studies of the percolation-type three-mode Zn 1−x Be x Se [31,32] and ZnSe 1−x S x [6,33] mixed crystals. As for the high-pressure study of phonon-polaritons, there are no data in the literature, not even for a pure compound.…”

Section: Introductionmentioning

confidence: 99%

Pressure-induced phonon freezing in the ZnSeS II–VI mixed crystal: phonon–polaritons andab initiocalculations

Hussein¹,

Pagès²,

Polian³

et al. 2016

J. Phys.: Condens. Matter

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Near-forward Raman scattering combined with ab initio phonon and bond length calculations is used to study the 'phonon-polariton' transverse optical modes (with mixed electrical-mechanical character) of the II-VI ZnSe1-x S x mixed crystal under pressure. The goal of the study is to determine the pressure dependence of the poorly-resolved percolation-type Zn-S Raman doublet of the three oscillator [1 × (Zn-Se), 2 × (Zn-S)] ZnSe0.68S0.32 mixed crystal, which exhibits a phase transition at approximately the same pressure as its two end compounds (~14 GPa, zincblende → rocksalt), as determined by high-pressure x-ray diffraction. We find that the intensity of the lower Zn-S sub-mode of ZnSe0.68S0.32, due to Zn-S bonds vibrating in their own (S-like) environment, decreases under pressure (Raman scattering), whereas its frequency progressively converges onto that of the upper Zn-S sub-mode, due to Zn-S vibrations in the foreign (Se-like) environment (ab initio calculations). Ultimately, only the latter sub-mode survives. A similar 'phonon freezing' was earlier evidenced with the well-resolved percolation-type Be-Se doublet of Zn1-x Be x Se (Pradhan et al 2010 Phys. Rev. B 81 115207), that exhibits a large contrast in the pressure-induced structural transitions of its end compounds. We deduce that the above collapse/convergence process is intrinsic to the percolation doublet of a short bond under pressure, at least in a ZnSe-based mixed crystal, and not due to any pressure-induced structural transition.

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Near-forward/high-pressure-backward Raman study of Zn_1 − x Be _x Se (x ~ 0.5) - evidence for percolation behavior of the long (Zn―Se) bond

Cited by 5 publications

References 43 publications

Recent advances in linear and non‐linear Raman spectroscopy. Part XI

Recent advances in linear and non‐linear Raman spectroscopy. Part XI

Near-forward Raman selection rules for the phonon-polariton in (Zn, Be)Se alloys

Pressure-induced phonon freezing in the ZnSeS II–VI mixed crystal: phonon–polaritons andab initiocalculations

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Near-forward/high-pressure-backward Raman study of Zn1 − x Be x Se (x ~ 0.5) - evidence for percolation behavior of the long (Zn―Se) bond

Cited by 5 publications

References 43 publications

Recent advances in linear and non‐linear Raman spectroscopy. Part XI

Recent advances in linear and non‐linear Raman spectroscopy. Part XI

Near-forward Raman selection rules for the phonon-polariton in (Zn, Be)Se alloys

Pressure-induced phonon freezing in the ZnSeS II–VI mixed crystal: phonon–polaritons andab initiocalculations

Contact Info

Product

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Near-forward/high-pressure-backward Raman study of Zn_1 − x Be _x Se (x ~ 0.5) - evidence for percolation behavior of the long (Zn―Se) bond