Ab initio calculations of vibrational spectra and their use in the identification of unusual molecules

Hess, B. Andes; Schaad, L. J.; Čárský, Petr; Zahradník, R.

doi:10.1021/cr00074a004

Cited by 334 publications

(101 citation statements)

References 14 publications

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“…For each vibrational mode, the integrated absorption intensity was calculated (units of cm mol À 1 ; ref. 48). To better fit the experimental spectra, we introduced a broadening by multiplying each computed absorption line of wavenumber f 0 with a unitless Lorentzian-like function of the form…”

Section: Methodsmentioning

confidence: 99%

How intermolecular geometrical disorder affects the molecular doping of donor–acceptor copolymers

et al. 2015

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Molecular doping of conjugated polymers represents an important strategy for improving organic electronic devices. However, the widely reported low efficiency of doping remains a crucial limitation to obtain high performance. Here we investigate how charge transfer between dopant and donor-acceptor copolymers is affected by the spatial arrangement of the dopant molecule with respect to the copolymer repeat unit. We p-dope a donor-acceptor copolymer and probe its charge-sensitive molecular vibrations in films by infrared spectroscopy. We find that, compared with a related homopolymer, a four times higher dopant/ polymer molar ratio is needed to observe signatures of charges. By DFT methods, we simulate the vibrational spectra, moving the dopant along the copolymer backbone and finding that efficient charge transfer occurs only when the dopant is close to the donor moiety. Our results show that the donor-acceptor structure poses an obstacle to efficient doping, with the acceptor moiety being inactive for p-type doping.

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Section: Methodsmentioning

confidence: 99%

How intermolecular geometrical disorder affects the molecular doping of donor–acceptor copolymers

et al. 2015

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“…Therefore, those data were obtained by means of FT-IR spectroscopy, which represents a powerful tool to monitor NCO groups in an aqueous environment. 4,5,9,10,20 A conversion of the NCO groups was obtained through integrated absorbance-peak areas: [21][22][23][24] A v dv bc a v dv bcA…”

Section: 2mentioning

confidence: 99%

“…That is especially true for the first-order kinetics where the starting concentration is not needed to obtain a conversion. 23 Another advantage of this approach is the elimination of the errors resulting from the water and NMP evaporation. The selected FT-IR spectra in a period of three days after the synthesis are presented in Figure 3.…”

Section: Ft-ir Spectra Evaluation and The Kinetic Modelmentioning

confidence: 99%

Monitoring of polyurethane dispersions after the synthesis

Ocepek¹,

Zabret²,

Kecelj³

2015

Mater. Tehnol.

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Chemical and physical parameters of the aqueous polyurethane dispersion (PUD) were studied after the synthesis. A prepolymer mixing process with a limited-chain extension step was used in order to examine the polymer and dispersion behavior with respect to the ageing time. Measurements of free isocyanate groups were performed with the aid of Fourier transform infrared spectroscopy (FT-IR). The pseudo-first-order kinetics of NCO disappearance was proposed and the value of the corresponding constant was determined. Additionally, particle size, particle size distribution, pH, conductivity and molecular mass were monitored and compared. Keywords: polyurethane dispersion, colloid, FT-IR V raziskavi smo preu~evali spreminjanje kemijskih in fizikalnih parametrov vodne poliuretanske disperzije (PUD) po sintezi. Disperzijo smo sintetizirali po postopku vme{avanja prepolimera z omejenim podalj{evanjem verig za preu~evanje polimerne disperzije z ozirom na~as po sintezi. Merjenje prostih izocianatnih skupin smo izvedli z metodo Fourierjeve transformacijske infrarde~e spektroskopije (FT-IR). Predpostavili smo kineti~ni model psevdoprvega reda z ozirom na reakcije izocianatnih skupin ter dolo~ili vrednost kineti~ne konstante. Dodatno smo spremljali in primerjali povpre~ne velikosti delcev, porazdelitev velikosti delcev, pH, prevodnost in molekulsko maso.

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“…Using four Lorentzians centered at 3311, 3387, 3422, and 3454 cm À1 , a near-perfect fit was obtained. Since the areas of the peaks, A, are proportional to the occupancies of the OH sites, 44 these were hereafter readily available (see Table II). The vibrational frequencies depend on the second derivative of the energy and are inherently more difficult to calculate than, e.g., simple energy differences.…”

Section: Vibrational Frequenciesmentioning

confidence: 99%

The atomic structure of protons and hydrides in Sm1.92Ca0.08Sn2O7−δ pyrochlore from DFT calculations and FTIR spectroscopy

Bork

Eurenius

Knee

et al. 2012

Journal of Applied Physics

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Structural, magnetic, and optical properties of Pr and Zr codoped BiFeO3 multiferroic ceramics J. Appl. Phys. 112, 094102 (2012) Structure and mechanical properties of tantalum mononitride under high pressure: A first-principles study J. Appl. Phys. 112, 083519 (2012) Effect of spin-orbit coupling on the actinide dioxides AnO2 (An=Th, Pa, U, Np, Pu, and Am): A screened hybrid density functional study J. Chem. Phys. 137, 154707 (2012) Additional information on J. Appl. Phys.

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Ab initio calculations of vibrational spectra and their use in the identification of unusual molecules

Cited by 334 publications

References 14 publications

How intermolecular geometrical disorder affects the molecular doping of donor–acceptor copolymers

How intermolecular geometrical disorder affects the molecular doping of donor–acceptor copolymers

Monitoring of polyurethane dispersions after the synthesis

The atomic structure of protons and hydrides in Sm1.92Ca0.08Sn2O7−δ pyrochlore from DFT calculations and FTIR spectroscopy

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