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Yao Y, Giapis KP. Intramolecular water-splitting reaction in single collisions of water ions with surfaces. Chem Sci 2017; 8:2852-2858. [PMID: 28553523 PMCID: PMC5427682 DOI: 10.1039/c6sc05065d] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2016] [Accepted: 01/14/2017] [Indexed: 11/24/2022] Open
Abstract
Direct water splitting into molecular hydrogen and atomic oxygen is demonstrated through single collisions of water ions with generic surfaces at hyperthermal energies.
We report the direct formation of H2 and O pair ions through single collisions of water ions with metal surfaces at hyperthermal energies. This unusual intramolecular reaction proceeds also for heavy and semi-heavy water, producing molecular D2 and HD ions. The selectivity of this water splitting channel is estimated at being between 9 and 13% versus complete dissociation. The collision kinematics support the hypothesis of a water molecule colliding with a single surface atom, thereby forming an excited precursor (Rydberg?) state, which dissociates subsequently to form the molecular hydrogen ion with high kinetic energy. Inelastic energy loss considerations yield an estimate for the energy of the excited precursor state of ∼7 eV and ∼11 eV at low and high incidence energies. These energies are close to the à state (1B1, 7.5 eV) and B state (1A1, 9.7 eV) of excited water (Rydberg states).
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Affiliation(s)
- Yunxi Yao
- Division of Chemistry and Chemical Engineering , California Institute of Technology , Pasadena , California 91125 , USA .
| | - Konstantinos P Giapis
- Division of Chemistry and Chemical Engineering , California Institute of Technology , Pasadena , California 91125 , USA .
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Yao Y, Giapis KP. Direct Hydrogenation of Dinitrogen and Dioxygen via Eley–Rideal Reactions. Angew Chem Int Ed Engl 2016. [DOI: 10.1002/ange.201604899] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Yunxi Yao
- Division of Chemistry and Chemical Engineering California Institute of Technology Pasadena CA 91125 USA
| | - Konstantinos P. Giapis
- Division of Chemistry and Chemical Engineering California Institute of Technology Pasadena CA 91125 USA
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Yao Y, Giapis KP. Direct Hydrogenation of Dinitrogen and Dioxygen via Eley-Rideal Reactions. Angew Chem Int Ed Engl 2016; 55:11595-9. [PMID: 27534611 DOI: 10.1002/anie.201604899] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2016] [Revised: 07/05/2016] [Indexed: 11/07/2022]
Abstract
Most Eley-Rideal abstraction reactions involve an energetic gas-phase atom reacting directly with a surface adsorbate to form a molecular product. Molecular projectiles are generally less reactive, may dissociate upon collision with the surface, and thus more difficult to prove that they can participate intact in abstraction reactions. Here we provide experimental evidence for direct reactions occurring between molecular N2 (+) and O2 (+) projectiles and surface-adsorbed D atoms in two steps: first, the two atoms of the diatomic molecule undergo consecutive collisions with a metal surface atom without bond rupture; and second, the rebounding molecule abstracts a surface D atom to form N2 D and O2 D intermediates, respectively, detected as ions. The kinematics of the collisional interaction confirms product formation by an Eley-Rideal reaction mechanism and accounts for inelastic energy losses commensurate with surface re-ionization. Such energetic hydrogenation of dinitrogen may provide facile activation of its triple bond as a first step towards bond cleavage.
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Affiliation(s)
- Yunxi Yao
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA, 91125, USA
| | - Konstantinos P Giapis
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA, 91125, USA.
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Guo Y, Yang Z, Hu B, Wang X, Song Z, Xu Q, Zhang B, Chen J, Yang B, Yang J. The continuous and discrete molecular orbital x-ray bands from Xe(q+) (12≤q≤29) +Zn collisions. Sci Rep 2016; 6:30644. [PMID: 27469425 DOI: 10.1038/srep30644] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2016] [Accepted: 07/08/2016] [Indexed: 11/08/2022] Open
Abstract
In this paper, the x-ray emissions are measured by the interaction of 1500-3500 keV Xe(q+) (q = 12, 15, 17, 19, 21, 23, 26 and 29) ions with Zn target. When q < 29, we observe Ll, Lα, Lβ1, Lβ2 and Lγ characteristic x-rays from Xe(q+) ions and a broad M-shell molecular orbital (MO) x-ray band from the transient quasi-molecular levels. It is found that their yields quickly increase with different rates as the incident energy increases. Besides, the widths of the broad MO x-ray bands are about 0.9-1.32 keV over the energy range studied and are proportional to v(1/2) (v = projectile velocity). Most remarkably, when the projectile charge state is 29, the broad x-ray band separates into several narrow discrete spectra, which was never observed before in this field.
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Abstract
Direct or Eley-Rideal reactions between energetic N^{+} and O^{+} projectiles and O atoms, adsorbed onto Pt and Pd surfaces, are studied experimentally at incidence energies between 20 and 200 eV. The exit energies of the diatomic molecular products NO and O_{2} depend linearly on the incidence energy of the corresponding projectiles. A reaction mechanism is proposed, where the incident projectile collides with a single metal atom on the surface, linked to an adsorbed O atom. At the apsis point, a high-energy transient state is formed between the projectile, substrate, and adsorbate atoms. As the projectile begins to rebound, the transient state decomposes into a diatomic molecule, consisting of the original projectile and the adsorbed O atom, which exits the surface with memory of the incidence energy. Energy and momentum conservation during this single-bounce event (atom in, molecule out) accurately predict the exit energy of the molecular product, thus capturing the kinematics of the direct reaction.
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Affiliation(s)
- Yunxi Yao
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, USA
| | - Konstantinos P Giapis
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, USA
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Abstract
Charge exchange in ion-surface collisions may be influenced by surface adsorbates to alter the charge state of the scattered projectiles. We show here that the positive-ion yield, observed during ion scattering on metal surfaces at low incident energies, is greatly enhanced by adsorbing electronegative species onto the surface. Specifically, when beams of N(+) and O(+) ions are scattered off of clean Au surfaces at hyperthermal energies, no positive ions are observed exiting. Partial adsorption of F atoms on the Au surface, however, leads to the appearance of positively charged primary ions scattering off of Au, a direct result of the increase in the Au work function. The inelastic energy losses for positive-ion exits are slightly larger than the corresponding ionization energies of the respective N and O atoms, which suggest that the detected positive ions are formed by surface reionization during the hard collision event.
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Affiliation(s)
- Yunxi Yao
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California, 91125, USA
| | - Konstantinos P Giapis
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California, 91125, USA.
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Chen L, Qiu S, Xiong F, Lu J, Liu P, Ding B, Li Y, Cui Y, Guo Y, Chen X. Nonadiabatic dynamics in energetic negative fluorine ions scattering from a Si(100) surface. J Chem Phys 2015; 143:114703. [PMID: 26395724 DOI: 10.1063/1.4930908] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The dependence of the negative-ion fractions on incident energy and angle is reported for 8.5-22.5 keV F(-) ions scattered from a Si(100) surface at a fixed scattering angle of 38°. The negative-ion fraction increases monotonically with incident velocity for specular scattering. In particular, the variation of the fraction with incident angle is bell shaped for a given incident energy. We interpret this variation using the incident-velocity effect at short distances where the yield of negative ions depends on the number of initial neutrals. It strongly indicates that at short distances, a dynamical equilibrium population is never achieved. This nonadiabatic feature is supported by simple calculations using modified rate equations.
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Affiliation(s)
- Lin Chen
- School of Nuclear Science and Technology, Lanzhou University, Lanzhou 730000, China
| | - Shunli Qiu
- School of Nuclear Science and Technology, Lanzhou University, Lanzhou 730000, China
| | - Feifei Xiong
- School of Nuclear Science and Technology, Lanzhou University, Lanzhou 730000, China
| | - Jianjie Lu
- School of Nuclear Science and Technology, Lanzhou University, Lanzhou 730000, China
| | - Pinyang Liu
- School of Nuclear Science and Technology, Lanzhou University, Lanzhou 730000, China
| | - Bin Ding
- School of Nuclear Science and Technology, Lanzhou University, Lanzhou 730000, China
| | - Yuan Li
- School of Nuclear Science and Technology, Lanzhou University, Lanzhou 730000, China
| | - Ying Cui
- School of Nuclear Science and Technology, Lanzhou University, Lanzhou 730000, China
| | - Yanling Guo
- School of Nuclear Science and Technology, Lanzhou University, Lanzhou 730000, China
| | - Ximeng Chen
- School of Nuclear Science and Technology, Lanzhou University, Lanzhou 730000, China
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Affiliation(s)
- Michael J. Gordon
- Department of Chemical Engineering, University of California—Santa Barbara, Santa Barbara, California 93106-5080, and Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125
| | - Xiangdong Qin
- Department of Chemical Engineering, University of California—Santa Barbara, Santa Barbara, California 93106-5080, and Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125
| | - Alex Kutana
- Department of Chemical Engineering, University of California—Santa Barbara, Santa Barbara, California 93106-5080, and Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125
| | - Konstantinos P. Giapis
- Department of Chemical Engineering, University of California—Santa Barbara, Santa Barbara, California 93106-5080, and Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125
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