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Vibrational dynamics of LiBH4 by infrared pump−probe and 2D spectroscopy


Andresen, E R; Gremaud, R; Borgschulte, A; Ramirez-Cuesta, A J; Züttel, A; Hamm, P (2009). Vibrational dynamics of LiBH4 by infrared pump−probe and 2D spectroscopy. Journal of Physical Chemistry. A, 113(46):12838-12846.

Abstract

Employing femtosecond IR pump−probe and 2D spectroscopy, we measure the vibrational dynamics of LiBH4 and several of its deuterium isotopomers. We find that the vibrational lifetime of various BH and BD stretching modes uniformly is ≈1.5 ps for all BH4−xDx− units (0 ≤ x ≤ 4). Subsequently, vibrational energy cascades down through BH and BD bending, facilitated by a strong Fermi resonance, into external (librational and translational) modes with a 3 ps time constant. Final thermalization of the energy is completed in about 100 ps. The vibrational spectra are purely homogeneously broadened indicating low inhomogeneity due to static disorder. We furthermore measured the anharmonic constants of various modes, which sets the benchmark for future ab initio calculations, and completed the first FTIR assignment of the stretching vibrations for the five BH4−xDx− units.

Abstract

Employing femtosecond IR pump−probe and 2D spectroscopy, we measure the vibrational dynamics of LiBH4 and several of its deuterium isotopomers. We find that the vibrational lifetime of various BH and BD stretching modes uniformly is ≈1.5 ps for all BH4−xDx− units (0 ≤ x ≤ 4). Subsequently, vibrational energy cascades down through BH and BD bending, facilitated by a strong Fermi resonance, into external (librational and translational) modes with a 3 ps time constant. Final thermalization of the energy is completed in about 100 ps. The vibrational spectra are purely homogeneously broadened indicating low inhomogeneity due to static disorder. We furthermore measured the anharmonic constants of various modes, which sets the benchmark for future ab initio calculations, and completed the first FTIR assignment of the stretching vibrations for the five BH4−xDx− units.

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Additional indexing

Item Type:Journal Article, refereed, original work
Communities & Collections:07 Faculty of Science > Department of Chemistry
Dewey Decimal Classification:540 Chemistry
Language:English
Date:9 October 2009
Deposited On:24 Jan 2010 08:28
Last Modified:18 Apr 2018 11:40
Publisher:American Chemical Society
ISSN:1089-5639
Funders:Swiss National Science Foundation (SNF), Danish Natural Science Research Council
OA Status:Closed
Publisher DOI:https://doi.org/10.1021/jp907746z
Project Information:
  • : FunderSNSF
  • : Grant ID
  • : Project TitleSwiss National Science Foundation (SNF)
  • : Funder
  • : Grant ID
  • : Project TitleDanish Natural Science Research Council

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