scholarly journals Ab initio infrared vibrational modes for neutral and charged small fullerenes (C 20 , C 24 , C 26 , C 28 , C 30 and C 60 )

2016 ◽  
Vol 374 (2076) ◽  
pp. 20150323 ◽  
Author(s):  
Jean-Joseph Adjizian ◽  
Alexis Vlandas ◽  
Jeremy Rio ◽  
Jean-Christophe Charlier ◽  
Chris P. Ewels
Keyword(s):  
Interstellar Medium ◽  
Ab Initio ◽  
Negative Charge ◽  
Spectral Lines ◽  
Ir Absorption ◽  
Vibrational Modes ◽  
Neutral Species ◽  
Ir Absorption Spectra ◽  
Buckminster Fullerene ◽  
C 30

We calculate the infrared (IR) absorption spectra using DFT B3LYP(6–311G) for a range of small closed-cage fullerenes, C n , n =20, 24, 26, 28, 30 and 60, in both neutral and multiple positive and negative charge states. The results are of use, notably, for direct comparison with observed IR absorption in the interstellar medium. Frequencies fall typically into two ranges, with C−C stretch modes around 1100–1500 cm −1 (6.7–9.1 μm) and fullerene-specific radial motion associated with under-coordinated carbon at pentagonal sites in the range 600–800 cm −1 (12.5–16.7 μm). Notably, negatively charged fullerenes show significantly stronger absorption intensities than neutral species. The results suggest that small cage fullerenes, and notably metallic endofullerenes, may be responsible for many of the unassigned interstellar IR spectral lines. This article is part of the themed issue ‘Fullerenes: past, present and future, celebrating the 30th anniversary of Buckminster Fullerene’.

scholarly journals Инфракрасные спектры комплекса фторотан-триметиламин в сжиженном криптоне

2021 ◽  
Vol 129 (4) ◽  
pp. 454
Author(s):  
С.М. Меликова ◽  
К.С. Рутковский
Keyword(s):  
Ab Initio Calculations ◽  
Ab Initio ◽  
Absorption Spectra ◽  
Enthalpy Of Formation ◽  
Fermi Resonance ◽  
Strong Increase ◽  
Ir Absorption ◽  
Ir Absorption Spectra ◽  
Anharmonic Interactions ◽  
The Enthalpy Of Formation

The IR absorption spectra of solutions of mixtures of halothane (C2HBrClF3) and trimethylamine ((CD3) 3N) in liquefied krypton were obtained and analyzed. Bands assigned to weak hydrogen-bonded complexes have been identified. The enthalpy of formation was estimated in a series of temperature experiments on the change in the integral intensities of the bands of monomers and complexes An extremely strong increase in the intensity of the second-order bands attributed to the first overtone of the bending CH vibrations of halothane was found. The effect is determined by strong anharmonic interactions of a resonant nature (Fermi resonance and Darling-Dennison resonance). The results of ab initio calculations reproduce the effects observed in the experiment.

scholarly journals Engineering of defects in fast neutron irradiated synthetic diamonds

2021 ◽  
Vol 2103 (1) ◽  
pp. 012076
Author(s):  
A A Khomich ◽  
A I Kovalev ◽  
R A Khmelnitsky ◽  
A V Khomich ◽  
A F Popovich ◽  
...  
Keyword(s):  
Chemical Vapor ◽  
Ir Absorption ◽  
Vibrational Modes ◽  
Intrinsic Defects ◽  
Small Width ◽  
Synthetic Diamonds ◽  
Ir Absorption Spectra ◽  
Chemical Vapor Deposited ◽  
Vibrational Bands ◽  
Local Vibrational Modes

Abstract Chemical vapor deposited (CVD) diamonds have been irradiated with fast reactor neutrons at fluencies F = 1·1018 and 3 · 1018 cm-2 and then heated at temperatures up to 1600 °C. The processes of annealing in and annealing out of various complexes of intrinsic defects responsible for vibrational and electron-vibrational bands in the IR absorption spectra have been studied in detail. Some tens of local vibrational modes and zero-phonon lines with rather small width caused by numerous complexes of intrinsic defects were observed in the 400-11000 cm-1 range.

Near-IR Absorption Spectra for the Buckminsterfullerene Anions: An Experimental and Theoretical Study

1992 ◽  
Author(s):  
Del R. Lawson ◽  
Daniel L. Feldheim ◽  
Colby A. Foss ◽  
Peter K. Dorhoug ◽  
C. M. Elliott
Keyword(s):  
Absorption Spectra ◽  
Theoretical Study ◽  
Ir Absorption ◽  
Near Ir ◽  
Ir Absorption Spectra

scholarly journals Phonons in Short-Period GaN/AlN Superlattices: Group-Theoretical Analysis, Ab initio Calculations, and Raman Spectra

Nanomaterials ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 286
Author(s):  
Valery Davydov ◽  
Evgenii Roginskii ◽  
Yuri Kitaev ◽  
Alexander Smirnov ◽  
Ilya Eliseyev ◽  
...  
Keyword(s):  
Theoretical Analysis ◽  
Ab Initio Calculations ◽  
Ab Initio ◽  
Raman Spectra ◽  
Density Functional ◽  
Structural Characteristics ◽  
Vibrational Modes ◽  
Phonon Modes ◽  
Short Period ◽  
Group Theoretical Analysis

We report the results of experimental and theoretical studies of phonon modes in GaN/AlN superlattices (SLs) with a period of several atomic layers, grown by submonolayer digital plasma-assisted molecular-beam epitaxy, which have a great potential for use in quantum and stress engineering. Using detailed group-theoretical analysis, the genesis of the SL vibrational modes from the modes of bulk AlN and GaN crystals is established. Ab initio calculations in the framework of the density functional theory, aimed at studying the phonon states, are performed for SLs with both equal and unequal layer thicknesses. The frequencies of the vibrational modes are calculated, and atomic displacement patterns are obtained. Raman spectra are calculated and compared with the experimental ones. The results of the ab initio calculations are in good agreement with the experimental Raman spectra and the results of the group-theoretical analysis. As a result of comprehensive studies, the correlations between the parameters of acoustic and optical phonons and the structure of SLs are obtained. This opens up new possibilities for the analysis of the structural characteristics of short-period GaN/AlN SLs using Raman spectroscopy. The results obtained can be used to optimize the growth technologies aimed to form structurally perfect short-period GaN/AlN SLs.

High Energy Local Vibrational Modes of Carbon Aggregates in SiC: Experimental and Theoretical Insight

2006 ◽  
Vol 527-529 ◽  
pp. 465-468 ◽  
Author(s):  
Alexander Mattausch ◽  
M. Bockstedte ◽  
Oleg Pankratov ◽  
John W. Steeds ◽  
S.A. Furkert ◽  
...  
Keyword(s):  
Ab Initio Calculations ◽  
Ab Initio ◽  
High Energy ◽  
Vibrational Modes ◽  
Energy Mode ◽  
Local Vibrational Modes ◽  
Theoretical Insight

We observe new photoluminescence centers in electron-irradiated 6H-SiC with phonon replicas up to 250 meV and clear threefold isotope splitting of the highest energy mode. Based on ab initio calculations, we discuss the tri-carbon anti-site (C3)Si and the di-interstitial (C2)Hex as models for these centers.

Study of the Infrared Absorption Spectra of Some Pyridine Derivatives-Iodine Complexes

1976 ◽  
Vol 30 (2) ◽  
pp. 200-204 ◽  
Author(s):  
F. M. Abdel Kerim ◽  
F. Abou El Fotouh
Keyword(s):  
Complex Formation ◽  
Absorption Spectra ◽  
Infrared Absorption ◽  
Ir Absorption ◽  
Pyridine Derivatives ◽  
Thermodynamic Constants ◽  
Ir Absorption Spectra ◽  
Infrared Absorption Spectra ◽  
The Stability ◽  
Iodine Complexes

The ir absorption spectra of some pyridine derivatives-iodine complexes were measured in the region 400 to 1400 cm−1 and the results are discussed. The effect of complex formation on the intensities of some of the bands was investigated. The thermodynamic constants of these complexes were calculated. It was found that the stability of the complex depends to a large extent on the electronegativity as well as the position of the substituent on the pyridine nucleus. The structures of formed complexes are discussed.

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