Spatial and velocity distributions of desorbing products in steady-state NO+CO and N2O+CO reactions on Pd(110) and Rh(110)

Matsushima, Toshiyasu; Ma, Yunsheng; Nakagoe, Osamu

doi:10.1380/ejssnt.2006.593

Cited by 4 publications

(5 citation statements)

References 42 publications

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“…The value at T S = 600 K was maximized to 4000 K around the collimation angle in the N 2 O + CO reaction. 34 It decreased slowly with an increasing shift from the collimation angle, consistent with the presence of two desorption components with different collimation angles. The distribution involves a small amount of the component expected by the Maxwell distribution at the surface temperature (the thermalized component), which yields the cosine component in the angular distribution.…”

Section: Steady-state No Reduction On Rh(100)supporting

confidence: 57%

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N2 emission in NO and N2O reduction on Rh(100) and Rh(110)

Matsushima

2007

Phys. Chem. Chem. Phys.

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The angular distribution of desorbing N(2) was studied in both the thermal decomposition of N(2)O(a) on Rh(100) at 60-140 K and the steady-state NO (or N(2)O) + D(2) reaction on Rh(100) and Rh(110) at 280-900 K. In the former, N(2) desorption shows two peaks at around 85 and 110 K. At low N(2)O coverage, the desorption at 85 K collimates at about 66 degrees off normal towards the [001] direction, whereas at high coverage, it sharply collimates along the surface normal. In the NO reduction on Rh(100), the N(2) desorption preferentially collimates at around 71 degrees off normal towards the [001] direction below about 700 K, whereas it collimates predominantly along the surface normal at higher temperatures. At lower temperatures, the surface nitrogen removal in the NO reduction is due to the process of NO(a) + N(a) --> N(2)O(a) --> N(2)(g) + O(a). On the other hand, in the steady-state N(2)O + D(2) reaction on Rh(110), the N(2) desorption collimates closely along the [001] direction (close to the surface parallel) below 340 K and shifts to ca. 65 degrees off normal at higher temperatures. In the reduction with CO, the N(2) desorption collimates along around 65 degrees off normal towards the [001] direction above 520 K, and shifts to 45 degrees at 445 K with decreasing surface temperature. It is proposed that N(2)O is oriented along the [001] direction on both surfaces before dissociation and the emitted N(2) is not scattered by adsorbed hydrogen.

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Section: Steady-state No Reduction On Rh(100)supporting

confidence: 57%

“…In the N 2 O thermal dissociation on Rh(110), the translational energy of desorbing N 2 is around 70 kJ mol À1 (about 4000 K). 34 The released energy in this dissociation was estimated to be around 240-340 kJ mol À1 on rhodium surfaces. 11 Therefore, only a small fraction of the energy is converted into the translational mode.…”

Section: Inclined N 2 Emissionmentioning

confidence: 99%

N2 emission in NO and N2O reduction on Rh(100) and Rh(110)

Matsushima

2007

Phys. Chem. Chem. Phys.

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“…The chopper with pseudorandomly positioned 255 slits of equal width is rotated at 196.1 Hz, where a time resolution of 20 s is obtained. 37 The other deviation, ⌬t b , is the time of flight of the molecules in the detector after the ionization at the top of QMS. The start signal for the measurement is provided by a photocoupler, which is triggered by the trigger hole ͓Fig.…”

Section: Methodsmentioning

confidence: 99%

“…The detected signal is then recorded by a multichannel analyzer with 20 s ϫ 255 channels. 37 The corrected TOF signals were finally deconvoluted by cross correlating with the function of pseudorandom chopper arrays by using software ͑IGOR PRO 6.031, WaveMetrics, Inc.͒ to obtain the true TOF spectrum. 1͑c͔͒ of the chopper.…”

Section: Methodsmentioning

confidence: 99%

Angle resolved intensity and velocity distributions of N2 desorbed by N2O decomposition on Rh(110)

Kondo

Sakurai

Matsushima

et al. 2010

The Journal of Chemical Physics

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The angle resolved intensity and velocity distributions of desorbing product N(2) were measured under a steady-state N(2)O+CO reaction on Rh(110) by cross-correlation time-of-flight techniques. Three-dimensional intensity distribution of N(2) has been constructed from the angle resolved intensity distributions in the planes along different crystal azimuths. N(2) desorption has been found to split into two lobes sharply collimated along 50-63 degrees off normal toward [001] and [001] directions, suggesting that N(2)O is decomposed through the transition state of N(2)O adsorbed with the molecular axis parallel to the [001] direction. From the velocity distribution analysis, each desorption lobe is found to consist of two components with different peak angles, ca. 50 degrees and 74 degrees off normal. In both lobe cases, desorption components have been interpreted by the model of two adsorption sites; N(2)O at on-top site emits N(2) to 50 degrees and that at bridge site emits to 74 degrees.

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“…The reaction and interaction between CO and NO on rhodium surfaces is important for automotive exhaust gas catalysis. , Hence, the reaction between NO and CO has extensively been studied on various single crystal surfaces of rhodium: (111), − (100), ,,,, (110), ,,− and (331) . Under steady-state conditions, the reaction between NO and CO proceeds via a generally accepted reaction mechanism, which includes the reversible adsorption of CO and NO, subsequent irreversible decomposition of NO forming nitrogen and oxygen atoms, and the reaction of oxygen with CO to form CO 2 . , Atomic nitrogen recombines to form N 2 at mild pressure conditions, while elevated pressure conditions also lead to recombination with NO to form N 2 O. , NO decomposition and CO 2 formation are surface structure sensitive, with the activity of both reactions on the Rh(100) surface lying in between that of the highly active Rh(110) and least reactive Rh(111) surface…”

Section: Introductionmentioning

confidence: 99%

Interaction and Reaction of Coadsorbed NO and CO on a Rh(100) Single Crystal Surface

et al. 2010

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In order to assess the possibility to follow surface reactions in a quantitative way by vibrational spectroscopy, a combination of temperature programmed reaction spectroscopy (TPRS) and reflection absorption infrared spectroscopy (RAIRS) has been used to study the decomposition of NO and the reaction between NO and CO on Rh(100). NO adsorbs in two configurations: in an almost parallel position at coverages below 0.18 ML and, in addition, in an upright position, probably on a bridge site, at all coverages. Coadsorbing NO and CO has only a minor influence on NO binding, whereas CO shifts gradually from top toward the bridge site under the influence of NO. Combining TP-RAIRS with TPRS during the reaction between CO and NO enabled us to simultaneously study site occupation and obtain qualitative surface coverages and desorption rates. At low surface coverages, NO dissociation is observed at lower temperatures than CO(2) formation. Near saturation, NO dissociation becomes blocked and shifts up in temperature. NO dissociation occurs simultaneously with CO(2) formation. To decompose NO, free surface sites have to be generated through surface diffusion or desorption of some CO. During NO decomposition, the formed oxygen atoms react with CO to form CO(2), creating more empty sites. This may lead to an explosive surface reaction.

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Spatial and velocity distributions of desorbing products in steady-state NO+CO and N2O+CO reactions on Pd(110) and Rh(110)

Cited by 4 publications

References 42 publications

N2 emission in NO and N2O reduction on Rh(100) and Rh(110)

N2 emission in NO and N2O reduction on Rh(100) and Rh(110)

Angle resolved intensity and velocity distributions of N2 desorbed by N2O decomposition on Rh(110)

Interaction and Reaction of Coadsorbed NO and CO on a Rh(100) Single Crystal Surface

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