Unusually low stretching frequency for CO adsorbed on Fe(100)

Benndorf, Carsten; Krüger, Bernd; Thieme, F.

doi:10.1016/0039-6028(85)90842-8

Cited by 111 publications

(35 citation statements)

References 9 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…5-8 X-ray photoelectron spectroscopy (XPS) together with low energy electron diffraction (LEED) resolved the stoichiometry and branching ratios between molecular desorption and dissociation in the dissociation reaction. 6,9 Vibrational electron energy loss spectroscopy (EELS) studies 7,8,10 showed typical vibrational frequencies a) Author to whom correspondence should be addressed. Electronic mail:…”

Section: Introductionmentioning

confidence: 99%

X-ray emission spectroscopy and density functional study of CO/Fe(100)

Gladh

Öberg

et al. 2012

The Journal of Chemical Physics

View full text Add to dashboard Cite

We report x-ray emission and absorption spectroscopy studies of the electronic structure of the predissociative α(3) phase of CO bound at hollow sites of Fe(100) as well as of the on-top bound species in the high-coverage α(1) phase. The analysis is supported by density functional calculations of structures and spectra. The bonding of "lying down" CO in the hollow site is well described in terms of π to π∗ charge transfer made possible through bonding interaction also at the oxygen in the minority spin-channel. The on-top CO in the mixed, high-coverage α(1) phase is found to be tilted due to adsorbate-adsorbate interaction, but still with bonding mainly characteristic of "vertical" on-top adsorbed CO similar to other transition-metal surfaces.

show abstract

Section: Introductionmentioning

confidence: 99%

X-ray emission spectroscopy and density functional study of CO/Fe(100)

Gladh

Öberg

et al. 2012

The Journal of Chemical Physics

View full text Add to dashboard Cite

show abstract

“…Measurements of electron-stimulateddesorption ion angular distributions (ESDIAD) are consistent with such a high tilt in showing a very weak signal for 0 + , but no bond angle information could be derived, probably due to the strong image forces which deflect and attenuate the desorbing ions. 2 We have thus applied x-ray photoelectron diffraction (XPD) for the first time to this intriguing adsorption state in an attempt to better understand its structure, combining both polar and azimuthal scans of core-level intensity in a way that has not been attempted before for such adsorbate structure studies. This method makes use of the dominance of highly-peaked forward scattering in core-level emission at energies of greater than approximately 500 eV.…”

mentioning

confidence: 99%

Structure of an unusual tilted state of CO on Fe(001) from x-ray photoelectron diffraction

Saiki¹,

Herman²,

Yamada³

et al. 1989

Phys. Rev. Lett.

View full text Add to dashboard Cite

The highly tilted a 3 state of CO on Fe(OOl) has been studied using combined polar and azimuthal xray photoelectron diffraction. A more accurate structural picture is derived, with the molecule being tilted at an angle of 55° ± 2° with respect to the surface normal along <100> azimuths and probably occupying fourfold hollows. An estimate is also made of the vertical C distance above the Fe surface. The utility of combined 0/0 x-ray photoelectron diffraction measurements for such unusual adsorbate structures is demonstrated.The existence of an "abnormal" or "unusual" type of surface bonding state of CO that involves a tilted or lying-down geometry and a considerably lowered CO stretch frequency has been discussed recently for several different transition-metal surfaces including Fe(OOl), 1 " 3 Cr(llO), 4,5 and Mo(OOl). 6 This state is of considerable interest because it may represent a precursor to dissociation with a weakened CO bond due to additional electronic interactions with the metal substrate. x However, little is known about the exact geometric structure of the CO for any of these cases. For the case of a^ CO on Fe(001) that we will consider here, electron-energy-loss (EELS) measurements show a very low CO stretch frequency of 1210 cm -1 . 1 Near-edge x-ray-absorption fine-structure (NEXAFS) measurements on this state have been used to deduce an elongation of the CO bond by 0.07 ± 0.02 A from a shift in the position of the a resonance. 3 From the relative lack of a change in the absolute and relative intensities of the n and a resonances with a change in radiation polarization, an estimated tilt angle with respect to normal of 45° ± 10° has been deduced. 3 However, the precision of this determination is not high, and it also was not possible in this study to specify whether there is any preferred azimuthal orientation of the tilt. Measurements of electron-stimulateddesorption ion angular distributions (ESDIAD) are consistent with such a high tilt in showing a very weak signal for 0 + , but no bond angle information could be derived, probably due to the strong image forces which deflect and attenuate the desorbing ions. 2 We have thus applied x-ray photoelectron diffraction (XPD) for the first time to this intriguing adsorption state in an attempt to better understand its structure, combining both polar and azimuthal scans of core-level intensity in a way that has not been attempted before for such adsorbate structure studies. This method makes use of the dominance of highly-peaked forward scattering in core-level emission at energies of greater than approximately 500 eV. 7 " 10 As these peaks have typical FWHM values of only about 20°, the precision of bond tilt determinations should be considerably higher than in measurements such as NEXAFS where the dependence on variable polarization goes as a more slowly varying cos 2 function. 3,810 Also, a simple single scattering cluster (SSC) model has been shown in prior studies to model very well this kind of intramolecular scattering, 7 " 10 although useful str...

show abstract

“…At higher exposures at 110 K the CO stretch frequency is observed at 1900-2055 cm -1 [443]. This change in frequency is attributed to the transition from a side-on bonding at low coverages at a end-on bonding at higher coverages [443].…”

Section: Properties Of Chemisorbed Comentioning

confidence: 73%

“…For CO/Fe (1 00) at exposures below 1 L at 350 K the CO stretch frequency is observed by high-resolution electron-energy loss-spectroscopy at 1180-1245 cm -1 [443]. At higher exposures at 110 K the CO stretch frequency is observed at 1900-2055 cm -1 [443].…”

Section: Properties Of Chemisorbed Comentioning

confidence: 79%

Structure and Surface Chemistry of Industrial Ammonia Synthesis Catalysts

Stoltze

1995

Ammonia

View full text Add to dashboard Cite

Unusually low stretching frequency for CO adsorbed on Fe(100)

Cited by 111 publications

References 9 publications

X-ray emission spectroscopy and density functional study of CO/Fe(100)

X-ray emission spectroscopy and density functional study of CO/Fe(100)

Structure of an unusual tilted state of CO on Fe(001) from x-ray photoelectron diffraction

Structure and Surface Chemistry of Industrial Ammonia Synthesis Catalysts

Contact Info

Product

Resources

About