Properties of Porous Silicon with Photoluminescence Enhanced by a Remote-Plasma Treatment

1992 ◽  
Vol 283 ◽  
Author(s):  
Y. Xiao ◽  
M. J. Heben ◽  
J. I. Pankove ◽  
Y. S. Tsuo
Keyword(s):  
Plasma Treatment ◽  
Photoluminescence Intensity ◽  
Remote Plasma ◽  
Laser Illumination ◽  
Spin Resonance ◽  
Resonance Data ◽  
Ion Laser ◽  
Electron Spin Resonance Data ◽  
Argon Ion ◽  
Processing Steps

ABSTRACTWe have developed remote-plasma and argon-ion laser-illumination treatments that enhance and stabilize the photoluminescent emission from porous Si (PS) that was electrochemically etched and thermally annealed. Infrared absorption spectroscopy revealed that the bonded oxygen content in the film was increased and the density of surface silicon dihydride bonds was reduced by these processing steps. The photoluminescence (PL) intensity of the treated films was initially about 15 times higher than that of the as—etched films, and increased further with the time of laser irradiation in air until a steady—state intensity was reached. The emission from the treated samples increases with decreasing temperature to a maximum intensity at about 100 K. Below 100 K, the photoluminescence intensity of the treated PS samples remains constant with decreasing temperature down to 7.7 K, whereas the as—etched samples, as well as siloxene, show a rapid decrease in photoluminescence intensity with decreasing temperature in this temperature range. Electron spin resonance data show that dangling bond densities in annealed PS films are reduced by the remote-plasma treatment.

Solvated electrons and the effect of coordination on the optical spectra of alkali metal cation – electron pairs in ethers

1977 ◽  
Vol 55 (19) ◽  
pp. 3356-3363 ◽  
Author(s):  
William Arthur Seddon ◽  
John Wallace Fletcher ◽  
Fred Charles Sopchyshyn ◽  
Ron Catterall
Keyword(s):  
Alkali Metal ◽  
Alkali Metal Cation ◽  
Ion Pairs ◽  
Alkali Metal Salts ◽  
Solvated Electrons ◽  
Electron Pairs ◽  
Monomeric Species ◽  
Spin Resonance ◽  
Resonance Data ◽  
Electron Spin Resonance Data

Pulse radiolysis of tetrahydrofuran (THF), dimethoxyethane (DME), diglyme (DG), and triglyme (TG), results in the formation of solvated electrons, es−, with optical band maxima λmax ≥ 1840 nm. In the presence of alkali metal salts transient optical bands are observed with λmax at ∼900 and ≥1600 nm. The latter bands are assigned to the formation of 'monomeric' species of stoichiometry M considered to be 'tight' and 'loose' ion-pairs, respectively. The proportion of 'loose' ion-pairs increases with decreasing temperature and increasing coordination of the solvent in the order [Formula: see text] These results demonstrate a good correlation with established electron spin resonance data in alkali metal solutions and substantiate the coexistence of at least two 'monomeric' species in DME and the glymes.

Stability in Amorphous Silicon

1987 ◽  
Vol 95 ◽  
Author(s):  
Z E. Smith ◽  
S. Wagner
Keyword(s):  
Electron Spin Resonance ◽  
Amorphous Silicon ◽  
Hydrogenated Amorphous Silicon ◽  
Thermal Recovery ◽  
Defect States ◽  
Spin Resonance ◽  
Resonance Data ◽  
Electron Spin Resonance Data ◽  
Gap States ◽  
Hydrogenated Amorphous

AbstractThe experimental phenomena associated with light-induced degradation and thermal recovery of hydrogenated amorphous silicon (a-Si:H) films are reviewed, with special emphasis on the limitations of each experimental technique. When several techniques are used in concert, a fuller picture emerges. Recent experiments suggest different positions in the band-gap of the paramagnetic-associated defect states (the dangling bonds) for doped and undopedfilms; this information can be combined with conductivity, sub-bandgap optical absorption and electron spin resonance data to yield a model for the density of gap states (DOS) in a- Si:H, including how the DOS changes upon illumination and annealing.

Conducting and Antistatic Composites for Space Applications

2004 ◽  
Vol 851 ◽  
Author(s):  
Mircea Chipara ◽  
Jagannathan Sankar ◽  
Petre Notinger ◽  
Denis Panaitescu ◽  
David Hui ◽  
...  
Keyword(s):  
Accurate Determination ◽  
Dc Conductivity ◽  
Filler Concentration ◽  
Space Applications ◽  
Polymeric Matrices ◽  
Spin Resonance ◽  
Resonance Data ◽  
Electron Spin Resonance Data ◽  
Polyaniline Composites

ABSTRACTThe percolative dependence of the DC conductivity on the volume concentration of fillers for composites obtained by dispersing conducting particles into polymeric matrices is studied in detail. An empirical Boltzmann like dependence is proposed for the modeling of the dependence of DC conductivity versus filler concentration. This expression allows for a more accurate determination of the percolation threshold in the case of broad percolations. It is shown that the loading of the polymeric matrices with conducting fillers produces percolative-like changes of various physical properties (such as the reciprocal of the tensile strength and the reciprocal of the double integral of the resonance spectrum). Experimental mechanical, electrical, and electron spin resonance data on polyvinylchloride-carbon, polyvinylchloride-polyaniline, and polyethylene-polyaniline composites are reported.

scholarly journals A new method for determining the concentration of vanadyl ions in clays

2011 ◽  
Vol 62 (2) ◽  
pp. 181-186 ◽  
Author(s):  
Pavle Premović ◽  
Budimir Ilić ◽  
Dragan Đorđević
Keyword(s):  
Electron Spin Resonance ◽  
Electron Spin ◽  
Room Temperature ◽  
Esr Spectra ◽  
New Method ◽  
Simple Method ◽  
Routine Work ◽  
Spin Resonance ◽  
Resonance Data ◽  
Electron Spin Resonance Data

A new method for determining the concentration of vanadyl ions in claysA novel and simple method for quantitatively determining the concentration of vanadyl ions in clays using electron spin resonance data has been developed. Several vanadyl standards with concentrations between 200-1000 ppm were prepared in a mixture of glycerol and kaolinite (KGa-2). The anisotropic electron spin resonance (ESR) spectra were recorded at room temperature, and the specific intensity of the line (attributed to nuclear spin m = -5/2||) was determined. For vanadyl concentrations between 50 ppm and 200 ppm, the standards must be prepared by mixing kaolinite with known vanadyl content (FBT2A-03) and kaolinite (GB1) containing no vanadyl. The method is applicable without modification to other clays and clay-rich sediments containing vanadyl ions. The whole procedure is very suitable for routine work.

Nickel(II) and copper(II) complexes of the 'tripod' ligand tris(2-benzimidazylmethyl)amine

1978 ◽  
Vol 56 (10) ◽  
pp. 1311-1318 ◽  
Author(s):  
Laurence K. Thompson ◽  
Baratham S. Ramaswamy ◽  
Robert D. Dawe
Keyword(s):  
Electron Spin Resonance ◽  
Solid State ◽  
Electron Spin ◽  
Copper Complexes ◽  
Acetone Solution ◽  
The Other ◽  
Solution Structures ◽  
Spin Resonance ◽  
Resonance Data ◽  
Electron Spin Resonance Data

A series of nickel(II) and copper(II) complexes of the title ligand are reported which appear to exhibit predominantly pseudo-octahedral structures in the solid state. Anion bridged dimeric structures are proposed for both nickel and copper; [Ni2(NTB)2X2]Y2 (X = Y= Cl, Br; X = Cl, Br, NCS; Y = BPh4), [Cu2(NTB)2X2]X2•2H2O (X = Cl, Br). The other octahedral derivatives appear to be monomeric; (Ni(NTB)X2] (X = NO3, NCS), [Ni(NTB)-(H2O)X]Y (X = NCS, Y = BPh4; X = CH3CN, Y = (ClO4)2), [Ni(NTB)(H2O)2]X2•2H2O (X = ClO4, BF4), [Cu(NTB)(NO3)2]•H2O. Five-coordinate derivatives were uncommon and in the case of three copper complexes trigonalbipyramidal structures are suggested in the solid state; [Cu(NTB)CI]BPh4, [Cu(NTB)(H2O)]X2•nH2O (X = BF4, n = 0; X = ClO4, n = 1). In acetone solution ail the copper complexes appear to be five-coordinate. Electron spin resonance data confirm trigonalbipyramidal solution structures and indicate [Formula: see text]with very small values of [Formula: see text] (60 − 80 × 10−4 cm−1).

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