A molecular beam surface scattering study of ammonia oxidation on the platinum(111) crystal face

Asscher, Micha; Guthrie, W. L.; Teng, Lin; Somorjai, G.A.

doi:10.1021/j150659a020

Cited by 59 publications

(31 citation statements)

References 2 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This implies a large energy transfer rate between CuF and the copper surface. The experimental observations are quite different for the NO/Pt(l 1 1) system, where significant rotational cooling was found in trapping desorption molecular beam scattering (42,43) as well as in associative desorption (13,14) and TPD experiments (44) at values for T, > 350 K.…”

Section: Discussionmentioning

confidence: 94%

“…This effect was small for OH and OD desorbing from Pt (12) but quite large for NO/Pt (13,14) and H 2 P d (15). Microscopic reversibility arguments by Brenig et al (16) and Muhlhausen et al (17) provide a plausible explanation of this effect: strongly rotating molecules have a lower sticking coefficient, which implies a lower desorption yield at high J.…”

Section: Introductionmentioning

confidence: 95%

“…In studies of associative or recombinative desorption by the groups of Lin, Somorjai, Zacharias, and co-workers (OH(OD)/Pt(lll) (12), NOPt(ll1) (13,14), and H2 (D2)/ Pd(100) (15)), rotational product analysis showed a "rotational cooling" effect, in which the desorbing diatomics take up on average less rotational energy per molecule than accommodation to the surface temperature would allow. This effect was small for OH and OD desorbing from Pt (12) but quite large for NO/Pt (13,14) and H 2 P d (15).…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Internal, translational, and angular momentum product state distributions of CuF molecules desorbing associatively from copper surfaces

Bracker¹,

Jakob²,

Näher³

et al. 1994

Can. J. Chem.

View full text Add to dashboard Cite

, 643 (1994). The dry etching reaction of solid copper surfaces with fluorine atoms or molecules has been studied with laser-induced fluorescence spectroscopy. The reaction product, copper monofluoride, CuF, is produced in the X'C+ electronic ground state and desorbs into the gas phase at surface temperatures above approximately 750 K. Rotationally resolved LIF excitation spectra of the C ' n + XIC+ band system of CuF molecules desorbing from an isotopically purified 6 ' C~ polycrystalline sample are obtained under conditions of coherent saturation. From the product state analysis it is deduced that the rovibrational product populations are in thermal equilibrium with the surface. The same holds for the translational velocity distribution obtained by Doppler-shift measurements. A pronounced polarization effect, particularly strong for Q branch transitions, can be traced back to photoselection of single-parity levels in the A doublets of the C l n state. A theoretical analysis for the distribution of J vectors, based on the formalism of Greene and Zare, shows that the measured degree of polarization is quantitatively in agreement with an isotropic distribution of rotational angular momentum vectors. The vibrational and translational product equilibration is not affected by changing the reactants from F2 molecules to F atoms, which increases the exoergicity of the overall reaction. The results are interpreted in terms of the absence of a barrier for desorption and a long residence time of the chemisorbed CuF molecules at the copper surface. The lack of any translational and rotational cooling is discussed within the framework of a model. Faisant appel i la spectroscopie de fluorescence induite au laser, on a CtudiC la rCaction de gravure B sec de surface solides de cuivre par des atomes ou des molCcules de fluor. Le monofluomre de cuivre, CuF, produit par la reaction se forme dans 1'Ctat Clectronique fondamental X'C+ et il se dCsorbe vers la phase gazeuse B des temperatures de surface suptrieures B environ 750 K. Les spectres d'excitation LIF, rCsolus en fonction de la rotation, du systkme de bandes C ' n + X'C+ des molCcules de CuF qui se dCsorbent d'un Cchantillon polycristallin de 6 3 C~ isotopiquement purifiC, ont Ct C obtenus dans des conditions de saturation cohtrente. En se basant sur une analyse de 1'Ctat du produit, on en dCduit que les populations de produit rovibrationnel sont en Cquilibre thermique avec la surface. I1 en est de m&me pour la distribution de la vitesse de translation obtenue par des mesures de diplacement Doppler. On peut attribuer un effet important de polarisation, particulikrement fort pour les transitions des branches Q, B une photosClection des niveaux de paritC unique dans les doublets A de 1'Ctat C l n .Une analyse thCorique de la distribution des niveaux J , basCe sur le formalisme de Greene et Zare, montre que le degrC de polarisation mesurC est en bon accord quantitatif avec une distribution isotrope des vecteurs des moments de rotation angulaire. L'Cquilibre vibrationnel et tr...

show abstract

Section: Discussionmentioning

confidence: 94%

Section: Introductionmentioning

confidence: 95%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Internal, translational, and angular momentum product state distributions of CuF molecules desorbing associatively from copper surfaces

Bracker¹,

Jakob²,

Näher³

et al. 1994

Can. J. Chem.

View full text Add to dashboard Cite

show abstract

“…Selective catalytic oxidation of ammonia is one of the most important heterogeneous catalytic processes [1], which has received increasing interest [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19]. The reaction proceeds through the three competing pathways to yield N-containing products of N 2 , NO and N 2 O.…”

Section: Introductionmentioning

confidence: 99%

Selective Oxidation of Ammonia by Co-adsorbed Oxygen on Iridium Surfaces: Formation of N2O

2014

View full text Add to dashboard Cite

Temperature programmed desorption is used to investigate ammonia oxidation by pre-adsorbed oxygen on planar Ir(210) and faceted Ir(210) with different facet sizes. Evidence is found for formation of N 2 O from both surfaces, which is the first observation of N 2 O production in catalytic ammonia oxidation under UHV conditions (\1 9 10 -9 Torr). The selectivity of the reaction to N 2 , N 2 O and NO can be tuned by oxygen pre-coverage, surface structure, and facet size. The reaction exhibits strong structure sensitivity on faceted Ir(210) versus planar Ir(210) and moderate size effects on faceted Ir(210) for average facet sizes of 5-14 nm. Graphical Abstract

show abstract

“…The mechanism of ammonia oxidation over different Pt catalysts (single crystals, wires, gauzes and supported catalysts) has been thoroughly studied during the last three decades [1][2][3][4][5][6][7][8][9]. Research was especially focused on the factors controlling product distribution, i.e.…”

Section: Introductionmentioning

confidence: 99%

Effect of different oxygen species originating from the dissociation of O2, N2O and NO on the selectivity of the Pt-catalysed NH3 oxidation

Kondratenko¹,

Baerns

2007

Catalysis Today

View full text Add to dashboard Cite

An effect of oxygen species formed from O 2 , N 2 O and NO on the selectivity of the catalytic oxidation of ammonia was studied over a polycrystalline Pt catalyst using the temporal analysis of products (TAP) reactor. The transient experiments were performed in the temperature range between 773 and 1073 K in a sequential pulse mode with a time interval of 0.2 s between the pulses of the oxidant (O 2 , N 2 O and NO) and NH 3 . In contrast to adsorbed oxygen species formed from NO, those from O 2 and N 2 O reacted with ammonia yielding NO. It is suggested that the difference between these oxidising agents may be related to the different active sites for dissociation of O 2 , N 2 O and NO, where oxygen species of various Pt-O strength are formed. Weaker bound oxygen species, which are active for NO formation, originate from O 2 and N 2 O rather than from NO. These species may be of bi-atomic nature. #

show abstract

A molecular beam surface scattering study of ammonia oxidation on the platinum(111) crystal face

Cited by 59 publications

References 2 publications

Internal, translational, and angular momentum product state distributions of CuF molecules desorbing associatively from copper surfaces

Internal, translational, and angular momentum product state distributions of CuF molecules desorbing associatively from copper surfaces

Selective Oxidation of Ammonia by Co-adsorbed Oxygen on Iridium Surfaces: Formation of N2O

Effect of different oxygen species originating from the dissociation of O2, N2O and NO on the selectivity of the Pt-catalysed NH3 oxidation

Contact Info

Product

Resources

About