The activities of evaporated metal films in gas chemisorption

Trapnell, B. M. W.

doi:10.1098/rspa.1953.0125

Cited by 138 publications

(16 citation statements)

References 14 publications

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“…Following the argument that the filled d-band of silver prevents interaction with H 2 [32,33,65], one may in turn suspect that silver that interacts with dihydrogen is characterized by structural defects at the surface or impurities that alter the electronic situation. The activated species from H 2 and D 2 on the silver surface must have opportunity to react with each other, which may arise because they are retained on the surface long enough while having sufficient mobility, or because the coverage is significant.…”

Section: Activation Of Dihydrogenmentioning

confidence: 99%

Activation of dihydrogen on supported and unsupported silver catalysts

Hohmeyer

Kondratenko

Bron

et al. 2010

Journal of Catalysis

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The activation of dihydrogen on silica, silver, and silica-supported silver (9 wt% Ag) was investigated. Both, silica and silver are individually able to dissociate dihydrogen. Silanol groups on silica undergo H→D exchange at 393 K in D2 as detected by IR spectroscopy. HD is observed in temporal analysis of products (TAP) experiments when H2 and D2 are sequentially pulsed on silver at 673 K; even when the time delay between the isotopes is 4 s, HD is formed, indicating that long-lived surface hydrogen species are present. Differential scanning calorimetry (DSC) shows that the activation of dihydrogen is an activated process: heat signals evoked through H2 pulses on Ag/SiO2 grow with increasing temperature (373523 K). Nonetheless, the presence of silver on the silica surface accelerates the Si-OH→Si-OD exchange. Investigation of the exchange kinetics on Ag/SiO2 shows that diffusion processes of activated hydrogen species are rate-determining at higher temperatures ( 373 K), when activation of D2 on silver becomes facile. Indications of diffusion limitation are observed already at 313 K on Pt/SiO2. TAP and DSC measurements show that H2 is more readily activated on silver that has been treated in O2 at 673 K followed by reduction in H2 at 673 K. Morphological changes induced to the silver surfaces or (sub)surface oxygen species are presumed responsible for this effect

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Section: Activation Of Dihydrogenmentioning

confidence: 99%

Activation of dihydrogen on supported and unsupported silver catalysts

Hohmeyer

Kondratenko

Bron

et al. 2010

Journal of Catalysis

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“…Furthermore, there was a definite, measurable increase in CO at filament change on day 286 of 1969, thus indicating the continuing importance of CO. Finally, previous laboratory work on surface interactions (Trapnell, 1953) indicates that gold is the least reactive of all metals and N 2 the least reactive molecule (except for the noble gases) on any metal, whereas CO is known to chemisorb on gold.…”

Section: Molecular Nitrogen Densitymentioning

confidence: 99%

“…Desorption of atomic oxygen is included to explain the finite atomic oxygen source density at apogee. The interaction of molecular oxygen with the surfaces is ignored, and recombined oxygen is assumed to appear immediately in the gas phase, because molecular oxygen is not expected to chemisorb on gold (Trapnell, 1953;Wood, Baker, and Wise, 1970) and would thus have a very short surface interaction time.…”

Section: Atomic Oxygen Densitymentioning

confidence: 99%

Role of gas-surface interactions in the reduction of Ogo 6 neutral particle mass spectrometer data

Hedin¹,

Hinton²,

Schmitt³

1973

J. Geophys. Res.

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Data obtained with the quadrupole mass spectrometer aboard the Ogo 6 satellite show the effects of significant surface interaction processes, including nearly complete recombination of incoming atomic oxygen on the walls of the instrument antechamber plus adsorption and desorption of oxygen and carbon monoxide. The observed data are fit by solving the time‐dependent continuity equations accounting for production and loss of atomic oxygen, molecular oxygen, and (in the case of mass 28) carbon monoxide. The surface parameters that best fit the data are selected and applied to the determination of ambient densities and their estimated errors.

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“…These low heats of adsorption allow the adsorption process to be reversible and Trapnell [56] shows that at low pressures and room temperature, the light hydrocarbons desorb with no measurable, i.e., less than 2% coverage at pressures less than 10-' Torr.…”

mentioning

confidence: 99%

“…Surface steps did not playa critical role in the adsorption properties of gold, in contrast to that of the similar chemical material, platinum. Earlier work by Trapnell [56] using polycrystalline gold films showed that reversible molecular adsorption of CO, C,H" C 2 H 2 , and other light hydrocarbons did occur with low heats of adsorption (0.4 eV Imolecule) for high pressures.…”

mentioning

confidence: 99%

Room Temperature Gold-Vacuum-Gold Tunneling Experiments

Teague¹

1986

J. RES. NAT. BUR. STAN.

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Preface Number 4An experiment has been completed which demonstrated quantum mechanical tunneling of electrons between two gold electrodes separated in vacuum. The tunneling current between the gold electrodes has been measured, for fixed voltages of 0.1 and 0.01 volts, as the electrode spacing was varied from a distance of approximately 2.0 nm down to a point where the electrodes touched. Current changes of over five orders of magnitude were found for electrode spacing changes of approximately 1.2 nm. For the first time, these data enable one to deduce the work function of the electrodes in a tunneling experiment from experimental parameters independent of the tunneling device. Also obtained were current-voltage characteristics for fixed electrode spacings in the direct tunneling region where electrode spacings were less than 2.0 nm. An analysis is given which attempts to deduce an absolute electrode spacing and tunneling area from the nonlinear properties of the I-V data and the curJuly-August 1986 rent versus spacing data. The analysis suggests that van der Waals and electrostatic forces playa major role in determining the I-V characteristics and that the tunneling area may be as small as 10-16 m 2 • Along with a review of the theory of work functions and quantum mechanical tunneling, numerical calculations of the tunneling current based on the free-electron model of the electrodes and the barrier, an image-potential reduced barrier, and a WKB approximation for the tunneling probability have been performed and compared with Simmons' theory and with the experimental results.Key words: metal-vacuum-metal tunneling; point-contact diode; scanning tunneling microscopy; temperature control; tunneling theory; vacuum tunneling; vibration isolation; work function Accepted: April 24, 1986 The following paper is a reproduction of the author's dissertation which was completed and submitted to North Texas State University in August 1978. A majority of the experimental work was performed at the National Bureau of Standards. Results from the experiments were first reported at the Spring 1978 APS meeting and later at a National Science Foundation Workshop on Opportunities for Microstructures Science, Engineering, and Technology held in Airlie, VA, November 19-22, 1978. While a complete description of the experiments and results is available as a publication from University Microfilms, pUblication in the more accessible form represented here has been prompted by requests from colleagues and by the significant number of recent references to the work. In accordance with the requests, the Board of Editors of the Journal of Research has agreed to publish the document unchanged except for the adAbout the Author: E. Clayton Teague is with the Center for Manufacturing Engineering in the NBS National Engineering Laboratory. dition of footnotes to identify recent work to which it is closely related. Renewed interest in these experiments has primarily resulted from the success and current widespread use of the scanning tunneling mic...

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The activities of evaporated metal films in gas chemisorption

Cited by 138 publications

References 14 publications

Activation of dihydrogen on supported and unsupported silver catalysts

Activation of dihydrogen on supported and unsupported silver catalysts

Role of gas-surface interactions in the reduction of Ogo 6 neutral particle mass spectrometer data

Room Temperature Gold-Vacuum-Gold Tunneling Experiments

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