Release of Oxygen from Palladium Oxide Cluster Ions by Heat

Abstract

Palladium oxide cluster ions, PdnOm(+), were prepared in the gas phase using laser ablation of a palladium rod in the presence of oxygen. The cluster ions were heated to 1000 K downstream from the cluster source (post heating), and the abundance of PdnOm(+) (n = 2-7) was examined using mass spectrometry. Temperature-programmed desorption experiments revealed that an oxygen molecule is released from oxygen-rich PdnOm(+), forming oxygen-deficient PdnOm-2(+). It was found that Pd6O4(+) was thermally stable up to 1000 K. The activation energy for oxygen molecule desorption has been obtained and compared with previous results by Lang et al.

Compositions and Isomer Separation of Palladium Oxide Cluster Cations Studied by Ion Mobility Mass Spectrometry

“…The CID processes observed in the present experiment were also consistent to some extent with the results of the mass spectrometric study on thermal dissociation of Pd n O m + . 12 In the following sections of this study, the CCSs and structures will be discussed for Pd , respectively, which were confirmed by the 2D plot (Figure 2). These overlap contributions are not used in the discussion below.…”

“…This argument was obtained from the results of the mass spectra at the higher injection energies (Figure 1b,c), and it was also supported by the results reported in the previous study. 12 Plots of the experimental and theoretical CCSs of Pd , the CCS of the most stable 2D branched structure, Ω calc = 60.5 Å 2 , along with those of the two 3D compact structures with low relative energies, Ω calc = 59.6 and 58.6 Å 2 , was found to be in good agreement with the experimental CCS (Ω exp = 59.1 ± 1.4 Å 2 ). Thus, the 2D branched isomer and 3D compact structures containing a tetrahedral metal-core configuration were assigned as plausible structures.…”

“…12,13 In such studies, Miyajima and Mafunéinvestigated thermal dissociation of the Pd n O m + cluster ions formed by laser desorption/ionization of palladium metal. 12 Lang et al determined the compositions of the cluster ions produced by the sputtering technique. 13 They revealed that a variety of compositions were observed, including bare metallic clusters and various metal−oxygen combinations, such as Pd To comprehend the formation process and structures of palladium oxide clusters, theoretical studies on structures of small cluster species were examined.…”

Catalytic Decomposition of NO by Cationic Platinum Oxide Cluster Pt3O4+

“…The Pt 3 O 4 + -catalyzed decomposition of NO was investigated by TDS and MS. Details of the experimental setup are shown in Figure S3. − The gas-phase Pt clusters were formed in a cluster source: a Pt metal rod (Furuya Metal Co., Ltd.) was vaporized by a Nd:YAG pulsed laser (355 nm) in the presence of 0.5% oxygen diluted with helium (total stagnation pressure = 0.8 MPa). The generated Pt n O m + ( n = 1–4) reacted with NO molecules in the fast flow reactor where He-diluted NO gas was introduced through a gas valve.…”

Structure Assignment and Separation of Isomers of Palladium Oxide Cluster Anions Studied by Ion Mobility Mass Spectrometry

“…As for the previous cluster research to understand the oxygen–palladium interactions, studies were limited mainly on Pd n O m + cluster cations. − Experimentally, Miyajima and Mafuné identified the compositions of Pd n O m + up to n = 7 by thermal desorption. According to this report, a variety of oxides including oxygen-deficient and oxygen-rich compositions were identified.…”