Comparative Studies of Optical Spectra in PbF2 at Different Excitations

1994 ◽  
Vol 348 ◽  
Author(s):  
V. K. Egorov ◽  
N.V. Klassen ◽  
V.D. Negrii ◽  
V.M. Prokopenko ◽  
S.Z. Shmurak ◽  
...  
Keyword(s):  
Comparative Studies ◽  
Room Temperature ◽  
Spectral Characteristics ◽  
Optical Spectra ◽  
Lead Fluoride ◽  
X Ray ◽  
Luminescence Centers ◽  
Room Temperature Luminescence ◽  
Α Particles

ABSTRACTThe spectral characteristics for cubic and orthorhombic lead fluoride excited by light with energies of 5–2.5 eV, X-ray, and α-particles were studied. It is shown that the room temperature luminescence in orthorhombic lead fluoride is connected with resonance excitations of some luminescence centers. Possible models of the centers responsible for this phenomenon are proposed.

Activation of Lead Fluoride Room Temperature Luminescence by Structural Modifications

1994 ◽  
Vol 348 ◽  
Author(s):  
D.L. Alov ◽  
A.V. Bazhenov ◽  
V.K. Egorov ◽  
G.A. Emelchenko ◽  
N.V. Klassen ◽  
...  
Keyword(s):  
Room Temperature ◽  
Structural Characteristics ◽  
Structural Defects ◽  
Luminescence Spectra ◽  
Lead Fluoride ◽  
Light Emitting ◽  
X Ray ◽  
Structural Modifications ◽  
Excited Luminescence ◽  
Room Temperature Luminescence

ABSTRACTThe connection of lead fluoride luminescence properties with its structural characteristics has been studied. Single crystals of the cubic and orthorombic phases, cubic and orthorombic powders, pressure compacted orthorombic ceramics, plastically deformed crystals were used. The photo- and X-ray excited luminescence spectra have been investigated. The experimental results have shown that the room temperature luminescence of lead fluoride can be accounted for local light emitting centers which are produced by the intrinsic structural defects in the orthorombic lead fluoride.

scholarly journals INFRARED SPECTRA OF THIOSACCHARINATES OF CADMIUM AND LEAD COMPARISON WITH THE ANALOGOUS METAL SACCHARINATES

2017 ◽  
Vol 27 (1-2) ◽  
Author(s):  
Gligor Jovanovski ◽  
Adnan Kahil ◽  
Orhideja Grupče
Keyword(s):  
Infrared Spectra ◽  
Room Temperature ◽  
Spectral Characteristics ◽  
Crystalline Hydrate ◽  
Water Molecules ◽  
X Ray ◽  
Weak Hydrogen Bonds ◽  
Deuterated Analogue ◽  
The Fourier Transform ◽  
Cadmium And Lead

A b s t r a c t: The Fourier transform (FT) infrared spectra of thiosaccharinates of cadmium and lead in the 4000–400 cm–1 region were studied. Although the observed resemblance between the spectra recorded in KBr pellets suggests a possible similarity between their structures as well, the powder X-ray diagrams show that these two compounds are not isomorphous. The presence of broad and intense bands in the region of the HOH stretchings shows that thiosaccharinate of cadmium is a crystalline hydrate and the spectral picture in the region of the O-D stretchings of the isotopically isolated HOD molecules in the partially deuterated analogue indicates that present in its structure are at least two types of crystallographically different water molecules involved in the formation of weak hydrogen bonds. The room temperature (RT) spectrum of lead thiosaccharinate in the region of the ν(HOH) modes differs significantly from the spectrum recorded at the boiling temperature of liquid nitrogen (LNT), which may perhaps be interpreted as an indication that a phase transition is taking place on lowering the temperature. The spectrum of lead thiosaccharinate was recorded in a Nujol mull as well. While the KBr and Nujol spectra are essentially identical in the region below 1600 cm–1, no bands are observed in the HOH stretching region of the mull spectra. In fact, it was shown that the appearance of the spectra of lead thiosaccharinates depends on the emulsion preparation rate. A comparison of the spectral characteristics of the thiosaccharinates of cadmium and lead with those of the corresponding saccharinates (their crystal structures are known) was made, special attention being paid to the analysis of the SO2 stretching region in the saccharinate and thiosaccharinate compounds.

Synthesis, Crystal Structure, Luminescence, and Nonlinear Optical Properties of 2-[(E)-[[4-[2-(4-Methoxyphenyl)ethynyl]phenyl] imino]methyl]-4- [(E)-phenyldiazenyl]phenol

2020 ◽  
Vol 17 (8) ◽  
pp. 618-623
Author(s):  
Sagar Subhash Mohite ◽  
Aditya Babasaheb Patil-Deshmukh ◽  
Sanjay Shamrao Chavan
Keyword(s):  
Crystal Structure ◽  
Optical Properties ◽  
Nonlinear Optical ◽  
Room Temperature ◽  
Second Harmonic ◽  
Monoclinic Structure ◽  
Single Crystal Diffraction ◽  
X Ray ◽  
Shg Efficiency ◽  
Room Temperature Luminescence

2-((E)-((4-((4-methoxyphenyl)ethynyl)phenyl)imino)methyl-4-((E)phenyldiazenyl)phenol (1) have been synthesized and characterized. X-ray single crystal diffraction study of the compound 1 reveal a monoclinic structure. Room temperature luminescence is observed for 1 in CH2Cl2 solution due to π* → π transition. The SHG efficiency by Kurtz powder technique indicating the compound 1 displayed the second harmonic generation (SHG) property.

Intense RT Visible Photoluminescence from Anodized Amorphous and Nanocrystalline Silicon Films

1992 ◽  
Vol 283 ◽  
Author(s):  
E. Bustarret ◽  
J. C. Bruyere ◽  
F. Muller ◽  
M. Ligeon
Keyword(s):  
Porous Silicon ◽  
Room Temperature ◽  
Nanocrystalline Silicon ◽  
Current Debate ◽  
X Ray ◽  
Boron Doped ◽  
Intense Luminescence ◽  
Conductive Substrates ◽  
Uv Excitation ◽  
Room Temperature Luminescence

ABSTRACTHeavily Boron-doped micrometer-thick amorphous (a-Si:B:H) or nanocrystalline (nc-Si) silicon layers have been deposited on a variety of conductive substrates by the 50 KHz PECVD of SiH4 / B2H6 / H2 mixtures at 320°C. These films have been partially electro-oxidized in a HF solution and then anodically oxidized in water in a manner similar to that yielding luminescent porous monocrystalline silicon layers (PcSL). Although the anodized films are x-ray amorphous, they yield intense luminescence properties at room temperature very similar to those of anodically oxidized PcSL with a similar vibrational spectrum. In both anodically oxidized materials, aging is shown to improve the external quantum efficiency. In amorphous anodized layers, optical microscopy under UV excitation showed strongly luminescent strain-related heterogeneities (20 μ,m in diameter) connected by non luminescent channels. The incidence of our results on the current debate about the origin of visible room-temperature luminescence in porous silicon and Si:O:H systems is discussed.

Unimportance of Siloxene in Luminescent Porous Silicon as Determined by Nexafs & Exafs

1993 ◽  
Vol 298 ◽  
Author(s):  
S.L. Friedman ◽  
M.A. Marcus ◽  
D.L. Adler ◽  
Y.-H. Xie ◽  
T.D. Harris ◽  
...  
Keyword(s):  
Fine Structure ◽  
Porous Silicon ◽  
Room Temperature ◽  
Emission Spectra ◽  
Porous Si ◽  
X Ray ◽  
Absorption Fine ◽  
X Ray Absorption ◽  
Room Temperature Luminescence ◽  
Combined Data

AbstractNear-edge-- and extended--x-ray absorption fine structure measurements, as well as luminescence excitation and emission spectra, were obtained from samples of porous Si and siloxene. Contrary to a recently proposed explanation for the room temperature luminescence in porous Si, the combined data indicate that siloxene is not principally responsible for the observed effect.

scholarly journals Octahedral CuII and NiII complexes manifesting with N′-[1-(pyridin-2-yl)ethylidene] acetohydrazide: Structural outlooks and spectral characteristics

2013 ◽  
Vol 11 (1) ◽  
pp. 116-122 ◽  
Author(s):  
Amitabha Datta ◽  
Jui-Hsien Huang ◽  
Jack Clegg ◽  
Pei-Hsin Liu ◽  
Sheng-Jie Chuang
Keyword(s):  
Room Temperature ◽  
Structural Investigation ◽  
Magnetic Moments ◽  
Spectral Characteristics ◽  
Distorted Octahedral Geometry ◽  
Central Metal Atom ◽  
Central Metal ◽  
X Ray Diffraction ◽  
X Ray ◽  
Distorted Octahedral

AbstractA tridentate hydrazone precursor, N′-[1-(pyridin-2-yl)ethylidene]acetohydrazide (L) (1:1 refluxed product of acetichydrazide and 2-acetylpyridine), produced two octahedral CuII and NiII derivatives, [CuL2]·NO3 (1) and [NiL2]·ClO4·H2O (2). Both are subjected to X-ray diffraction system, and structural investigation shows that the central metal atom (CuII or NiII) adopts a distorted octahedral geometry with N4O2 donor sets by coordination of a pair of independent hydrazone precursors. Besides X-ray study, IR and UV-vis spectra, thermal analysis and room temperature magnetic moments are utilized for establishing significant characteristics of both complexes. It is apparent that the M-Npyridine bonds are slightly longer than the M-Nimino bonds, Cu1-N1 and Cu1-N4 [2.300(2) and 2.038(2) Å] for 1 and Ni1-N1 and Ni1-N4 [2.075(2) and 2.084(1) Å] for 2, Cu1-N2 and Cu1-N5 [2.062(1) and 1.932(1) Å] for 1 and Ni1-N2 and Ni1-N5 [2.008(2) and 1.975(2) Å] for 2, respectively. As per our observation, the effective magnetic moment value (µeff) is found to be 1.77 B.M. for 1 and 3.06 BM for 2, respectively.

Electron Microscopy of Human Gallstones

1971 ◽  
Vol 29 ◽  
pp. 296-297
Author(s):  
C. Wolpers ◽  
R. Blaschke
Keyword(s):  
Electron Microscopy ◽  
Room Temperature ◽  
Bile Pigment ◽  
X Ray Diffraction ◽  
Triclinic Crystal System ◽  
X Ray ◽  
Follow Up Study ◽  
Infra Red ◽  
Main Components

Scanning microscopy was used to study the surface of human gallstones and the surface of fractures. The specimens were obtained by operation, washed with water, dried at room temperature and shadowcasted with carbon and aluminum. Most of the specimens belong to patients from a series of X-ray follow-up study, examined during the last twenty years. So it was possible to evaluate approximately the age of these gallstones and to get information on the intensity of growing and solving.Cholesterol, a group of bile pigment substances and different salts of calcium, are the main components of human gallstones. By X-ray diffraction technique, infra-red spectroscopy and by chemical analysis it was demonstrated that all three components can be found in any gallstone. In the presence of water cholesterol crystallizes in pane-like plates of the triclinic crystal system.

Opening images of synaptic vesicles and calcium localization by means of microwave fixation method

1990 ◽  
Vol 48 (2) ◽  
pp. 182-183
Author(s):  
Vinci Mizuhira ◽  
Hiroshi Hasegawa
Keyword(s):  
Synaptic Vesicles ◽  
Room Temperature ◽  
Osmium Tetroxide ◽  
Sampling Procedure ◽  
Fixation Method ◽  
Potassium Oxalate ◽  
X Ray ◽  
Cacodylate Buffer ◽  
Ultrathin Sections ◽  
Microwave Fixation

Microwave irradiation (MWI) was applied to 0.3 to 1 cm3 blocks of rat central nervous system at 2.45 GHz/500W for about 20 sec in a fixative, at room temperature. Fixative composed of 2% paraformaldehyde, 0.5% glutaraldehyde in 0.1 M cacodylate buffer at pH 7.4, also contained 2 mM of CaCl2 , 1 mM of MgCl2, and 0.1% of tannic acid for conventional observation; and fuether 30-90 mM of potassium oxalate containing fixative was applied for the detection of calcium ion localization in cells. Tissue blocks were left in the same fixative for 30 to 180 min after MWI at room temperature, then proceeded to the sampling procedure, after postfixed with osmium tetroxide, embedded in Epon. Ultrathin sections were double stained with an useal manner. Oxalate treated sections were devided in two, stained and unstained one. The later oxalate treated unstained sections were analyzed with electron probe X-ray microanalyzer, the EDAX-PU-9800, at 40 KV accelerating voltage for 100 to 200 sec with point or selected area analyzing methods.

Evidence for ordered Fe3Ni

1987 ◽  
Vol 45 ◽  
pp. 216-217
Author(s):  
K.B. Reuter ◽  
D.B. Williams ◽  
J.I. Goldstein
Keyword(s):  
Experimental Data ◽  
Martensitic Transformation ◽  
Electron Diffraction ◽  
Room Temperature ◽  
Direct Evidence ◽  
Transformation Product ◽  
Iron Meteorites ◽  
X Ray ◽  
Ni Content ◽  
Temperature Transformation

In the Fe-Ni system, although ordered FeNi and ordered Ni3Fe are experimentally well established, direct evidence for ordered Fe3Ni is unconvincing. Little experimental data for Fe3Ni exists because diffusion is sluggish at temperatures below 400°C and because alloys containing less than 29 wt% Ni undergo a martensitic transformation at room temperature. Fe-Ni phases in iron meteorites were examined in this study because iron meteorites have cooled at slow rates of about 10°C/106 years, allowing phase transformations below 400°C to occur. One low temperature transformation product, called clear taenite 2 (CT2), was of particular interest because it contains less than 30 wtZ Ni and is not martensitic. Because CT2 is only a few microns in size, the structure and Ni content were determined through electron diffraction and x-ray microanalysis. A Philips EM400T operated at 120 kV, equipped with a Tracor Northern 2000 multichannel analyzer, was used.

Electron Microscope study of commensurate-incommensurate phase transition in BaZnGeO4

1990 ◽  
Vol 48 (4) ◽  
pp. 172-173
Author(s):  
Naoki Yamamoto ◽  
Makoto Kikuchi ◽  
Tooru Atake ◽  
Akihiro Hamano ◽  
Yasutoshi Saito
Keyword(s):  
Phase Transition ◽  
Electron Microscope Study ◽  
Room Temperature ◽  
Hexagonal Lattice ◽  
Ferroelectric Materials ◽  
Temperature Phase ◽  
X Ray Diffraction ◽  
X Ray ◽  
Periodic Arrays ◽  
Modulation Wave Vector

BaZnGeO4 undergoes many phase transitions from I to V phase. The highest temperature phase I has a BaAl2O4 type structure with a hexagonal lattice. Recent X-ray diffraction study showed that the incommensurate (IC) lattice modulation appears along the c axis in the III and IV phases with a period of about 4c, and a commensurate (C) phase with a modulated period of 4c exists between the III and IV phases in the narrow temperature region (—58°C to —47°C on cooling), called the III' phase. The modulations in the IC phases are considered displacive type, but the detailed structures have not been studied. It is also not clear whether the modulation changes into periodic arrays of discommensurations (DC’s) near the III-III' and IV-V phase transition temperature as found in the ferroelectric materials such as Rb2ZnCl4.At room temperature (III phase) satellite reflections were seen around the fundamental reflections in a diffraction pattern (Fig.1) and they aligned along a certain direction deviated from the c* direction, which indicates that the modulation wave vector q tilts from the c* axis. The tilt angle is about 2 degree at room temperature and depends on temperature.

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