Evidence of Silica Polymerization During Internal Nucleation of Glassy Lithium Disilicate

1993 ◽  
Vol 321 ◽  
Author(s):  
Jane W. Adams ◽  
Bernard H.W.S. De Jong
Keyword(s):  
Lithium Disilicate ◽  
Core Level ◽  
Photoelectron Spectra ◽  
X Ray ◽  
Principal Problem ◽  
Silica Polymerization

ABSTRACTThe principal problem in developing a theory of internal nucleation lies in the constitution of the nascent nuclei. To get at this constitution in an internally nucleating glass, oxygen and lithium core level x-ray photoelectron spectra have been measured on glassy and nucleated lithium disilicate and on the three stable crystalline compounds in the Li2O-SiO2 system. Our results indicate that nucleated lithium disilicate glass consists of completely polymerized silica in the formation of which non-bridging oxygens are consumed. During this silica polymerization lithium atoms move away from presumably four-fold coordinated sites towards higher coordinated ones.

X-Ray Photoelectron Spectroscopic Studies of Palladium Dispersed on Carbon Surfaces Modified by Ion Beams and Plasmatic Oxidation

1995 ◽  
Vol 60 (3) ◽  
pp. 383-392 ◽  
Author(s):  
Zdeněk Bastl
Keyword(s):  
Binding Energy ◽  
Photoelectron Spectroscopy ◽  
Surface Coverage ◽  
Spectroscopic Studies ◽  
Core Level ◽  
Graphite Surface ◽  
Photoelectron Spectra ◽  
Surface Layers ◽  
X Ray ◽  
Core Level Binding Energy

The effects of ion bombardment and r.f. plasma oxidation of graphite surfaces on subsequent growth and electronic properties of vacuum deposited palladium clusters have been investigated by methods of X-ray photoelectron spectroscopy (XPS) and Auger electron spectroscopy with X-ray excitation (XAES). Due to the significantly increased density of surface defects on which the nucleation process occurs the bulk value of the Pd 3d core level binding energy is achieved at higher surface coverage by palladium on bombarded surfaces than on ordered graphite. Angle resolved photoelectron spectra of oxidized graphite surfaces reveal significant embedding of oxygen in graphite surface layers. The C 1s and O 1s photoelectron spectra are consistent with presence of two major oxygen species involving C-O and C=O type linkages which are not homogeneously distributed within the graphite surface layers. Two effects were observed on oxidized surfaces: an increase of palladium dispersion and interaction of the metal clusters with surface oxygen groups. Using the simple interpretation of the modified Auger parameter the relaxation and chemical shift contributions to the measured Pd core level shifts are estimated. In the region of low surface coverage by palladium the effect of palladium-oxygen interaction on Pd core level binding energy exceeds the effects of increased dispersity.

Intersubband Absorption in Gallium Arsenide Implanted with Silicon Negative Ions

2019 ◽  
Vol 19 (03) ◽  
pp. 1950019
Author(s):  
A. R. Yadav ◽  
S. K. Dubey ◽  
R. L. Dubey ◽  
N. Subramanyam ◽  
I. Sulania
Keyword(s):  
Gallium Arsenide ◽  
Binding Energy ◽  
Crystallite Size ◽  
Photoelectron Spectroscopy ◽  
Nir Spectroscopy ◽  
Negative Ions ◽  
Core Level ◽  
Photoelectron Spectra ◽  
Gaas Sample ◽  
X Ray

Gallium arsenide (GaAs) implanted with silicon forming intersubband of SiGaAs is a promising material for making novel electronic and optoelectronic devices. This paper is focused on finding optimum fluence condition for formation of intersubband of SiGaAs in GaAs sample after implantation with 50[Formula: see text]keV silicon negative ions with fluences varying between [Formula: see text] and [Formula: see text] ions cm[Formula: see text]. The GaAs samples were investigated using X-ray photoelectron spectroscopy (XPS), UV-Vis.-NIR spectroscopy and X-ray diffraction (XRD) techniques. The X-ray photoelectron spectra for unimplanted sample showed peaks at binding energy of 18.74[Formula: see text]eV and 40.74[Formula: see text]eV indicating Ga3d and As3d core level, whereas the corresponding core level peaks for implanted sample were observed at binding energy of 19.25[Formula: see text]eV and 41.32[Formula: see text]eV. The shift in Ga3d and As3d core levels towards higher binding energy side in the implanted sample with respect to unimplanted sample were indicative of change in chemical state environment of Ga–As bond. The relative atomic percentage concentration of elemental composition measured using casa XPS software showed change in As/Ga ratio from 0.89 for unimplanted sample to 1.13 for sample implanted with the fluence of [Formula: see text] ion cm[Formula: see text]. The UV-Vis-NIR spectra showed absorption band between 1.365[Formula: see text]eV and 1.375[Formula: see text]eV due to the formation of intersubband of SiGaAs for fluences greater than [Formula: see text] ion cm[Formula: see text]. The GaAs crystallite size calculated using Brus formula was found to vary between 162[Formula: see text]nm and 540[Formula: see text]nm, respectively. The XRD spectra showed the presence of Bragg’s peak at 53.98∘ indicating (311) silicon reflection. The silicon crystallite size determined from full width at half maxima (FWHM) of (311) XRD peak was found to vary between 110[Formula: see text]nm and 161[Formula: see text]nm, respectively.

Molecular-cluster study of core-level x-ray photoelectron spectra: Application toFeCl2

1985 ◽  
Vol 32 (8) ◽  
pp. 5391-5401 ◽  
Author(s):  
B. W. Veal ◽  
D. E. Ellis ◽  
D. J. Lam
Keyword(s):  
Core Level ◽  
Photoelectron Spectra ◽  
Molecular Cluster ◽  
X Ray

Composition of oxides and nitrides from line shapes of metal core level x-ray photoelectron spectra

1992 ◽  
Vol 19 (1-12) ◽  
pp. 205-210 ◽  
Author(s):  
L. Galán ◽  
P. Prieto ◽  
C. Morant ◽  
L. Soriano ◽  
J. M. Sanz ◽  
...  
Keyword(s):  
Core Level ◽  
Photoelectron Spectra ◽  
Metal Core ◽  
X Ray ◽  
Line Shapes
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