Application of HREEL spectroscopy to characterize adsorbates on insulating metal oxide surfaces: carboxylates on MgO(100)

Petrie, W.T.; Vohs, John M.

doi:10.1016/0039-6028(91)90546-5

Cited by 46 publications

(14 citation statements)

References 5 publications

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“…For comparison, a prefactor of 10 17 s –1 was measured from TPD for the associative desorption of dissociatively adsorbed water on Fe 2 O 3 (012) . Such large prefactors have also been reported for molecularly adsorbed species at defects (where it has limited mobility) …”

Section: Experimental Resultsmentioning

confidence: 93%

“…2 Such large prefactors have also been reported for molecularly adsorbed species at defects (where it has limited mobility). 48 Heat of Water Adsorption. In this paper, we define the term heat of adsorption as the negative of the differential standard molar enthalpy change for the adsorption reaction, with the gas and the sample surface being at the same temperature.…”

Section: ■ Experimental Resultsmentioning

confidence: 99%

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Water Dissociative Adsorption on NiO(111): Energetics and Structure of the Hydroxylated Surface

et al. 2016

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The energetics of the reactions of water with metal oxide surfaces are of tremendous interest for catalysis, electrocatalysis, and geochemistry, yet the energy for the dissociative adsorption of water was only previously measured on one well-defined oxide surface, iron oxide. In the present paper, the enthalpy of the dissociative adsorption of water is measured on NiO(111)-2 × 2 at 300 K using single-crystal adsorption calorimetry. The differential heat of dissociative adsorption decreases with coverage from 170 to 117 kJ/mol in the first 0.25 ML of coverage. Water adsorbs molecularly on top of that, with a heat of ∼92 kJ/mol. Density functional theory (DFT) calculations reproduce the measured energies well (all within 17 kJ/mol) and provide insight into the atomic-level structure of the surfaces studied experimentally. They show that the oxygen-terminated O-octo(2 × 2) structure is the most stable NiO(111)-2 × 2 termination and gives reaction energies with water that are more consistent with the calorimetry results than the metal-terminated surface. They show that water adsorbs dissociatively on this (2 × 2)-O-octo surface to produce a hydroxyl-covered surface with a heat of adsorption of 171 ± 5 kJ/mol in the low-coverage limit (very close to 170 kJ/mol experimentally) and an integral heat that decreases by 14 kJ/mol up to saturation (compared to ∼30 kJ/mol experimentally). Sensitivity of this reaction’s energy to choice of DFT method is tested using a variety of different exchange correlation functionals, including HSE06, and found to be quite weak.

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Section: Experimental Resultsmentioning

confidence: 93%

Section: ■ Experimental Resultsmentioning

confidence: 99%

Water Dissociative Adsorption on NiO(111): Energetics and Structure of the Hydroxylated Surface

et al. 2016

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“…Using aberration-corrected cylindrical optics, an energy resolution better than 0.5 meV has been achieved [31]. Historically, HR-EELS has been thought of as a surface science technique, often for studying vibrations of molecular adsorbates [32], and has not been applied widely in the field of quantum materials. But the information it provides should directly complement that from ARPES and STM, which are also surface techniques.…”

Section: Why M-eels?mentioning

confidence: 99%

Measurement of the dynamic charge response of materials using low-energy, momentum-resolved electron energy-loss spectroscopy (M-EELS)

et al. 2017

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One of the most fundamental properties of an interacting electron system is its frequency-and wave-vector-dependent density response function, χ(q, ω). The imaginary part, χ (q, ω), defines the fundamental bosonic charge excitations of the system, exhibiting peaks wherever collective modes are present. χ quantifies the electronic compressibility of a material, its response to external fields, its ability to screen charge, and its tendency to form charge density waves. Unfortunately, there has never been a fully momentum-resolved means to measure χ(q, ω) at the meV energy scale relevant to modern electronic materials. Here, we demonstrate a way to measure χ with quantitative momentum resolution by applying alignment techniques from x-ray and neutron scattering to surface high-resolution electron energy-loss spectroscopy (HR-EELS). This approach, which we refer to here as "M-EELS", allows direct measurement of χ (q, ω) with meV resolution while controlling the momentum with an accuracy better than a percent of a typical Brillouin zone. We apply this technique to finite-q excitations in the optimally-doped high temperature superconductor, Bi 2 Sr 2 CaCu 2 O 8+x (Bi2212), which exhibits several phonons potentially relevant to dispersion anomalies observed in ARPES and STM experiments. Our study defines a path to studying the long-sought collective charge modes in quantum materials at the meV scale and with full momentum control.

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“…1, 5,6 Although the Fuchs-Kliewer phenomenon has been known and understood for TMOs for approximately 30 years, 7 most reported TMO HREEL spectra have been performed on only a handful of materials, most notably MgO, [8][9][10] NiO, [11][12][13][14] TiO 2 , [15][16][17] SrTiO 3 18 and Al 2 O 3 , 10,19-21 both in thin film and in crystalline form. 1-4 Known as Fuchs-Kliewer phonons, the normal loss modes for these materials have substantial dipolar scattering cross sections due to the collective, out of phase cation and anion oscillations.…”

Section: Introductionmentioning

confidence: 99%

Deconvolution of the Co3O4(110) Fuchs–Kliewer phonon spectrum

Marsh¹,

Petitto²,

Harbison³

et al. 2005

Journal of Vacuum Science & Technology A: Vacuum, Surfaces,

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Surface composition and structure of Co 3 O 4 (110) and the effect of impurity segregationThe Fuchs-Kliewer phonon spectrum of single crystal Co 3 O 4 ͑110͒ has been treated with a Fourier transform log deconvolution method, which removes multiple scattering features from the single loss spectrum. Auger electron spectroscopy ͑AES͒, x-ray photoelectron spectroscopy ͑XPS͒ and low-energy electron diffraction ͑LEED͒ were first used to characterize the Co 3 O 4 crystal establishing the cleanliness, composition, and order of the ͑110͒ surface. High resolution electron energy loss spectroscopy ͑HREELS͒ was then used to obtain the phonon spectrum for an incident electron energy of 3.77 eV. Due to the strong dipole cross section for the Fuchs-Kliewer phonon modes, intense multiple electron scattering was detected, which provided a complicated and overlapping combination of all possible loss modes. Deconvolution removed the multiple loss modes to produce well-resolved Fuchs-Kliewer fundamental phonon losses at 218, 373, 598, and 682 cm −1 ͑27.0, 46.2, 74.1, and 84.6 meV͒. These values are compared to the fundamental loss energies obtained by resolving the overlapping peak structure with standard peak fitting procedures, which confirmed the single loss energies obtained with the deconvolution procedure. Deconvolution results from the four fundamental phonon spectrum of single crystal Co 3 O 4 ͑110͒ were also compared to those from the simpler spectra of CoO͑100͒ and thin-film CoO͑100͒-Co 3 O 4 epitaxy and some practical aspects of the deconvolution process discussed in this context.

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Application of HREEL spectroscopy to characterize adsorbates on insulating metal oxide surfaces: carboxylates on MgO(100)

Cited by 46 publications

References 5 publications

Water Dissociative Adsorption on NiO(111): Energetics and Structure of the Hydroxylated Surface

Water Dissociative Adsorption on NiO(111): Energetics and Structure of the Hydroxylated Surface

Measurement of the dynamic charge response of materials using low-energy, momentum-resolved electron energy-loss spectroscopy (M-EELS)

Deconvolution of the Co3O4(110) Fuchs–Kliewer phonon spectrum

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