The arrangement of CO adsorbed on a Pt(533) surface

Brandt, Robert K.; Greenler, Robert G.

doi:10.1016/0009-2614(94)00252-5

Cited by 17 publications

(10 citation statements)

References 9 publications

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“…38−40 In those studies, a preferred occupation of the metal edge sites was revealed, associated with a strongly red-shifted C−O stretch frequency with respect to terrace-bound species. 41 This finding fully agrees with the blueshifted hindered rotational mode of edge CO observed here. A strengthened CO-metal bond and a weakened internal molecular bond both indicate an enhanced interaction of CO with low-coordinated metal atoms located at step edges.…”

supporting

confidence: 91%

“…For Au and Pd islands, a blueshift of the hindered rotational energy for edge versus terrace CO has been found in our study (Table ). Similar shifts were earlier observed with nonlocal spectroscopic techniques, e.g., HREELS and IRAS, where the spatially averaged vibrational response of CO was probed on flat and vicinal metal surfaces. − In those studies, a preferred occupation of the metal edge sites was revealed, associated with a strongly red-shifted C–O stretch frequency with respect to terrace-bound species . This finding fully agrees with the blue-shifted hindered rotational mode of edge CO observed here.…”

supporting

confidence: 89%

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Single Molecule Vibrational Spectroscopy: CO Bonding to Edge and Terrace Positions on Ag, Au, and Pd Islands on NiAl(110)

Wallis

Nilius

2016

J. Phys. Chem. Lett.

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The vibrational properties of single CO molecules adsorbed on nanosized Ag, Au, and Pd islands on a NiAl(110) surface were studied with a scanning tunneling microscope. The sensitivity of single molecule vibrational spectroscopy to aspects of the local environment is demonstrated by comparative studies of CO-metal bond vibrations at island terrace and island edge sites. Vibrational spectra of single CO molecules adsorbed on Ag, Au, and Pd island terraces showed peaks at 27, 32, and 44 meV, respectively, which are assigned to the hindered rotational mode. CO molecules on Au and Pd island edges, on the other hand, showed blue-shifted hindered rotational modes at 34 and 46 meV, respectively. On Au islands, CO molecules showed a strong preference for adsorption on edges, while no such preference was observed on Pd.

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supporting

confidence: 91%

supporting

confidence: 89%

Single Molecule Vibrational Spectroscopy: CO Bonding to Edge and Terrace Positions on Ag, Au, and Pd Islands on NiAl(110)

Wallis

Nilius

2016

J. Phys. Chem. Lett.

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“…This suggests that at the ir frequency, E increases by a factor 1.64 on going from sites on the terrace to the edge; however, the change in CO and the strong dipole coupling between the two species complicate the analysis. [10][11][12] A similar experiment was reported by Lambert and Tobin 13 but their analysis suggested that the ir cross sections for CO at edge and terrace sites on Pt͑335͒ are almost equal. This appeared to confirm the observations of Reutt-Robey et al ͓When the experiments in Refs.…”

Section: Introductionsupporting

confidence: 71%

CO on Pt(335): Electric field screening on a stepped surface

Wang

Tobin

Lambert

et al. 1995

The Journal of Chemical Physics

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We compare CO's response to electric fields at edge and terrace sites on the stepped Pt͑335͒ surface. The comparison is made at zero frequency and at the frequency of the C-O stretch vibration. Atop-bonded CO is observed with reflection-absorption ir spectroscopy ͑RAIRS͒, electroreflectance vibrational spectroscopy ͑EVS͒, and high-resolution electron energy loss spectroscopy ͑HREELS͒. Coadsorbed H or O is used to control the CO adsorption site. With both RAIRS and HREELS the measured vibrational cross-section of atop CO at the step edge is 2.0Ϯ0.2 times greater than for CO on the terrace. The vibrational Stark effect-the change of CO's vibrational frequency with externally applied electrostatic field-is also a factor 2.0Ϯ0.2 larger for atop CO at the step edge than it is for atop CO on the terrace. Because the vibrational cross section varies as the square of the field while the Stark effect is linear, a model in which CO responds to the screened local field at a single point cannot simultaneously explain the observed site dependence of both the vibrational Stark effect and the vibrational cross section. The most plausible explanation is that CO's response to electric fields is nonlocal. A simple model is presented that can account for our data.

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“…This phenomenon is not unexpected as changes in the coordination of the adsorbing sites and in their relative abundance in the different samples can produce big differences in the molar extinction coefficient of adsorbed CO, as a consequence of changes in the bond polarity, dipole-dipole effects, and so on. For monocrystalline PtA C H T U N G T R E N N U N G (533), non-linearity between the integrated IR absorption and surface coverage has been clearly shown [35] and was ascribed to differences in the CO vibrational polarizability on different adsorption sites and adsorption geometries, that is, normal or tilted with respect to the surface. On gold clusters of different sizes and geometries, these factors can play a significant role.…”

Section: Samplementioning

confidence: 99%

Highly Dispersed Gold on Zirconia: Characterization and Activity in Low‐Temperature Water Gas Shift Tests

et al. 2008

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Gold-loaded zirconia and sulfated zirconia catalysts were tested in the low-temperature water gas shift reaction. The samples were characterized by N2 adsorption analysis, temperature-programmed reduction, X-ray diffraction, pulse-flow CO chemisorption, FTIR spectroscopy, and high-resolution transmission electron microscopy. A reference catalyst, Au/TiO2, provided by the World Gold Council was investigated for comparison. CO chemisorption and FTIR data indicate the presence of only highly dispersed gold clusters on the sulfated sample and both small clusters and small particles on the non-sulfated sample. Both gold-zirconia catalysts are much more active than the Au/TiO2 reference sample over all the temperature range investigated. The sample prepared on sulfated zirconia exhibits higher stability than the catalyst on unmodified zirconia. The prominent role in the water gas shift reaction of gold clusters in close contact with the support was deduced.

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The arrangement of CO adsorbed on a Pt(533) surface

Cited by 17 publications

References 9 publications

Single Molecule Vibrational Spectroscopy: CO Bonding to Edge and Terrace Positions on Ag, Au, and Pd Islands on NiAl(110)

Single Molecule Vibrational Spectroscopy: CO Bonding to Edge and Terrace Positions on Ag, Au, and Pd Islands on NiAl(110)

CO on Pt(335): Electric field screening on a stepped surface

Highly Dispersed Gold on Zirconia: Characterization and Activity in Low‐Temperature Water Gas Shift Tests

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