Isotope effect in hydrogen/deuterium-absorbing Pd nanoparticles revealed by X-ray powder diffraction and by a multi-component MO method

Takayoshi Ishimoto, Masanori Tachikawa, Miho Yamauchi, Hiroshi Kitagawa, Hiroaki Tokiwa, Umpei Nagashima

Research output: Contribution to journalArticle

16 Citations (Scopus)

Abstract

The isotope effect in Pd nanoparticles that absorb hydrogen or deuterium (i.e., H/D isotope effect) was studied experimentally and theoretically. First, the geometries (i.e., lattice parameters) of such Pd nanoparticles exposed to hydrogen or deuterium gas were measured by using X-ray powder diffraction to determine the lattice parameters. Then, the geometrical and electronic relaxations of PdnH- and PdnD- (n = 1-6) clusters, which modeled Pd nanoparticles exposed to hydrogen or deuterium gas, were calculated by using a multi-component molecular orbital (MC_MO) method, which uses first principles of quantum mechanics to account for the quantum effect of proton/deuteron. Experimental results from the diffraction patterns show that the bond distances of Pd nanoparticles exposed to hydrogen gas (and thus had absorbed hydrogen) were about 0.005 Å longer than those of exposed to deuterium gas. These results were confirmed by analytical results from the MC_MO calculation for PdnH- and Pd nD- clusters. Therefore, the local geometrical changes due to the H/D isotope effect control the geometrical changes of the entire nanoparticle. Both the experimental and analytical results also show that the nanoparticle (cluster) size influences the extent of the H/D isotope effect on the geometrical changes. Based on the analytical results, the electronic charge densities are only slightly influenced by the H/D isotope effect.

Original languageEnglish
Pages (from-to)1775-1780
Number of pages6
Journaljournal of the physical society of japan
Volume73
Issue number7
DOIs
Publication statusPublished - Jul 1 2004

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isotope effect
deuterium
nanoparticles
hydrogen
diffraction
x rays
gases
lattice parameters
molecular orbitals
electronics
deuterons
quantum mechanics
diffraction patterns
protons
geometry

All Science Journal Classification (ASJC) codes

  • Physics and Astronomy(all)

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Isotope effect in hydrogen/deuterium-absorbing Pd nanoparticles revealed by X-ray powder diffraction and by a multi-component MO method. / Ishimoto, Takayoshi; Tachikawa, Masanori; Yamauchi, Miho; Kitagawa, Hiroshi; Tokiwa, Hiroaki; Nagashima, Umpei.

In: journal of the physical society of japan, Vol. 73, No. 7, 01.07.2004, p. 1775-1780.

Research output: Contribution to journalArticle

Ishimoto, Takayoshi ; Tachikawa, Masanori ; Yamauchi, Miho ; Kitagawa, Hiroshi ; Tokiwa, Hiroaki ; Nagashima, Umpei. / Isotope effect in hydrogen/deuterium-absorbing Pd nanoparticles revealed by X-ray powder diffraction and by a multi-component MO method. In: journal of the physical society of japan. 2004 ; Vol. 73, No. 7. pp. 1775-1780.
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