Reflectance spectra of surface states in magnesium oxide and calcium oxide

Zecchina, Adriano; Lofthouse, M.G.; Stone, F. S.

doi:10.1039/f19757101476

Cited by 180 publications

(74 citation statements)

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“…Highly dehydroxylated, high area oxide surfaces, namely alkaline earth oxides, give rise to strong emission bands which are assigned to It/1(MeO) +-3t/1(Me+O-) charge transfer transitions on sites in low coordination compatible with high index planes [360,361]. Similar phenomena have also been observed for thoria surfaces [362].…”

Section: Optical Spectroscopiessupporting

confidence: 51%

Nature and Estimation of Functional Groups on Solid Surfaces

Boehm

Knözinger

1983

Catalysis

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Section: Optical Spectroscopiessupporting

confidence: 51%

Nature and Estimation of Functional Groups on Solid Surfaces

Boehm

Knözinger

1983

Catalysis

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“…13,14 Prior to CO adsorption, the pellet was outgassed at 1123 K. The final surface area was 200 m 2 /g. IR spectra were obtained by a Bruker IFS 48 instrument; the resolution was 4 cm -1 .…”

Section: Methodsmentioning

confidence: 99%

Can the Three-Coordinated Mg Site of MgO Accommodate More Than One CO Molecule?

Pelmenschikov¹,

Morosi²,

Gamba³

et al. 2000

J. Phys. Chem. B

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A new mechanism of CO adsorption at the three-coordinated (3c) Mg sites of MgO is proposed on the basis of a quantum chemical study of the phenomenon of gradual diminution of the 2202 cm -1 band of the OC‚ Mg 3c species upon increase of the CO pressure above 10 -1 Torr [Coluccia, S., et al. Spectrochim. Acta 1993, 49A, 1289. The MgO surface is modeled by bare Mg 10 O 10 and Mg 16 O 16 clusters at the HF and DFT (B3LYP) levels of theory. We examine the hypotheses that the intensity decrease may be due to (i) the static dipoledipole or/and inductive interactions with the CO molecules at the neighboring Mg 4c sites and (ii) the coadsorption of two or three CO molecules at the Mg 3c sites. The computed frequency shifts and binding energies suggest that the discussed phenomenon is due to the coadsorption of two CO molecules at the Mg 3c sites.

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“…The reflection data acquired using this technique do not always provide sufficient information to perform an accurate Monte Carlo simulation-some reflectors are fluorescent or change their angular reflectance distributions with incidence angle. Integrating sphere materials include barium sulfate (BaSO 4 ) [8][9][10][11][12][13][14], magnesium oxide (MgO) [8,[11][12][13][14][15][16][17], and polytetrafluorethylene (PTFE) based reflectors [18][19][20], and these reflector materials have been extensively studied. Other reflectors that are frequently used in optical systems include titanium dioxide (TiO 2 ) paint [11,16,21], Tyvek ® paper [22,23], ESR (Enhanced Specular Reflector) film [24,25], and Spectralon [19,26].…”

Section: Introductionmentioning

confidence: 99%

Reflectivity Spectra for Commonly Used Reflectors

Janecek

2012

IEEE Trans. Nucl. Sci.

133

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Abstract-Monte Carlo simulations play an important role in developing and evaluating the performance of radiation detection systems. To accurately model a reflector in an optical Monte Carlo simulation, the reflector's spectral response has to be known. We have measured the reflection coefficient for many commonly used reflectors for wavelengths from 250 nm to 800 nm. The reflectors were also screened for fluorescence and angular distribution changes with wavelength. The reflectors examined in this work include several polytetrafluoroethylene (PTFE) reflectors, Spectralon, GORE diffuse reflector, titanium dioxide paint, magnesium oxide, nitrocellulose filter paper, Tyvek paper, Lumirror, Melinex, ESR films, and aluminum foil. All PTFE films exhibited decreasing reflectivity with longer wavelengths due to transmission. To achieve reflectivity in the 380 to 500 nm range, the PTFE films have to be at least 0.5 mm thick-nitrocellulose is a good alternative if a thin diffuse reflector is needed. Several of the reflectors have sharp declines in reflectivity below a cut-off wavelength, including (420 nm), ESR film (395 nm), nitrocellulose (330 nm), Lumirror (325 nm), and Melinex (325 nm). PTFE-like reflectors were the only examined reflectors that had reflectivity above 0.90 for wavelengths below 300 nm. Lumirror, Melinex, and ESR film exhibited fluorescence. Lumirror and Melinex are excited by wavelengths between 320 and 420 nm and have their emission peaks located at 440 nm, while ESR film is excited by wavelengths below 400 nm and the emission peak is located at 430 nm. Lumirror and Melinex also exhibited changing angular distributions with wavelength.

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Reflectance spectra of surface states in magnesium oxide and calcium oxide

Cited by 180 publications

References 0 publications

Nature and Estimation of Functional Groups on Solid Surfaces

Nature and Estimation of Functional Groups on Solid Surfaces

Can the Three-Coordinated Mg Site of MgO Accommodate More Than One CO Molecule?

Reflectivity Spectra for Commonly Used Reflectors

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