Silver Cluster Formation in Implanted A12O3 Single Crystals

1995 ◽  
Vol 396 ◽  
Author(s):  
F.L. Freire ◽  
N. Broil ◽  
G. Mariotto
Keyword(s):  
Single Crystals ◽  
Cluster Formation ◽  
Low Frequency ◽  
Silver Cluster ◽  
Laser Frequency ◽  
Implantation Dose ◽  
Silver Clusters ◽  
Linear Absorption ◽  
Broad Absorption Band ◽  
Depth Profiles

AbstractSingle crystals of sapphire were implanted at room temperature with 300 keV-Ag+. The metal precipitate was characterized by a multitechnique approach including RBS, optical absorption and Raman spectroscopy. RBS measurements were used to determine the depth-profiles of the implanted ions. Ag depth profiles, derived from RBS are in good agreement with the results predicted by Monte Carlo simulations. Linear absorption spectroscopy has been used to characterize the effects of the ion fluence on the optical properties of the metal colloids in the UV-Vis region. The broad absorption band due to the surface plasmon resonance shows an appreciable red-shift when the fluence of bombarding ions increases. Raman scattering from acoustic vibrations of the silver clusters progressively shifts toward the laser frequency with increasing implantation dose. From low-frequency Raman spectra an evaluation of the average size of metal aggregates was derived.

Theoretical Study of Stability, Structure, and Optical Spectra of Ultra-Small Silver Clusters Using Density Functional Theory

2020 ◽  
Author(s):  
mohsen farshad ◽  
Duwage Perera ◽  
jayendran Rasaiah
Keyword(s):  
Density Functional Theory ◽  
Formation Mechanism ◽  
Density Functional ◽  
Cluster Formation ◽  
Experimental System ◽  
Silver Cluster ◽  
Optical Spectra ◽  
Structure Stability ◽  
Silver Clusters ◽  
Functional Theory

Our article is a systematic study toward understanding the mechanism of silver cluster formation. We calculated optical spectra of ultra-small silver clusters using time-dependent density functional theory (TDDFT) and compared our results with time-resolved UV-Vis spectra obtained from pulse radiolysis experiments during early stages of cluster formation. This comparative study indicates that the formation mechanism of silver clusters occurs through both monomer and ion addition growth pathways. Also, we calculated free energy of formation of small cationic and neutral clusters using density functional theory (DFT) which shows the thermodynamic stability of cationic clusters. In a conventional experimental system with the common reducing agents, the formation of cationic clusters is kinetically favored owing to the dominance of charged ions relative to neutral atoms in the system. While we show the stability of small cationic clusters relative to neutral clusters, collectively, we deduce that the monomer addition along with ion addition growth pathway is involved in silver cluster formation mechanism. We further show the effect of solvent and water ligands on structure, stability, and optical properties of small clusters.

Theoretical Study of Stability, Structure, and Optical Spectra of Ultra-Small Silver Clusters Using Density Functional Theory

2020 ◽  
Author(s):  
mohsen farshad ◽  
Duwage Perera ◽  
jayendran Rasaiah
Keyword(s):  
Density Functional Theory ◽  
Formation Mechanism ◽  
Density Functional ◽  
Cluster Formation ◽  
Experimental System ◽  
Silver Cluster ◽  
Optical Spectra ◽  
Structure Stability ◽  
Silver Clusters ◽  
Functional Theory

Our article is a systematic study toward understanding the mechanism of silver cluster formation. We calculated optical spectra of ultra-small silver clusters using time-dependent density functional theory (TDDFT) and compared our results with time-resolved UV-Vis spectra obtained from pulse radiolysis experiments during early stages of cluster formation. This comparative study indicates that the formation mechanism of silver clusters occurs through both monomer and ion addition growth pathways. Also, we calculated free energy of formation of small cationic and neutral clusters using density functional theory (DFT) which shows the thermodynamic stability of cationic clusters. In a conventional experimental system with the common reducing agents, the formation of cationic clusters is kinetically favored owing to the dominance of charged ions relative to neutral atoms in the system. While we show the stability of small cationic clusters relative to neutral clusters, collectively, we deduce that the monomer addition along with ion addition growth pathway is involved in silver cluster formation mechanism. We further show the effect of solvent and water ligands on structure, stability, and optical properties of small clusters.

Low-Frequency Central Peaks In Relaxor Ferroelectric PZN-9%PT Single Crystals

2007 ◽  
Vol 347 (1) ◽  
pp. 25-29 ◽  
Author(s):  
Jae-Hyeon Ko ◽  
Do Han Kim ◽  
Seiji Kojima
Keyword(s):  
Single Crystals ◽  
Low Frequency ◽  
Relaxor Ferroelectric

Low frequency Raman spectra of the liquid and plastic crystal phases of O2, N2, CO, and of Ar crystals with these molecules as guests

1982 ◽  
Vol 60 (9) ◽  
pp. 1358-1364 ◽  
Author(s):  
N. H. Rich ◽  
M. J. Clouter ◽  
H. Kiefte ◽  
S. F. Ahmad
Keyword(s):  
Single Crystals ◽  
Raman Spectra ◽  
Phonon Mode ◽  
Low Frequency ◽  
Impurity Molecule ◽  
Spectral Features ◽  
Background Impurity ◽  
Crystal Phases ◽  
Distinct Features ◽  
Frequency Feature

Low frequency Raman spectra of single crystals of orientationally disordered phases of oxygen, nitrogen, and carbon monoxide, and spectra of those substances as liquids show two linear segments in semi-log plots. Slopes of the higher frequency segments are nearly equal for all cases; slopes of the lower frequency segments are particular to the substance and are nearly the same in both liquid and crystal for O2 and CO. Spectra of single crystals of argon doped with O2, N2, or CO show two distinct features superimposed on a sloping background. Impurity molecule reorientation apparently accounts satisfactorily for all spectral features, but translation–rotation coupling may allow a contribution to the higher frequency feature arising from a local phonon mode in argon.

Effect of Purity on Dislocation-Induced Relaxations in Molybdenum Single Crystals

2015 ◽  
Vol 363 ◽  
pp. 106-111
Author(s):  
Shigeru Suzuki ◽  
Alfred Seeger
Keyword(s):  
Internal Friction ◽  
Single Crystals ◽  
High Purity ◽  
Low Frequency ◽  
Activation Process ◽  
Dislocation Interaction ◽  
Dissolved Carbon ◽  
Dislocation Pinning ◽  
Friction Measurements ◽  
Substitutional Impurities

Dislocation-induced relaxations in different molybdenum single crystals were investigated by means of low-frequency internal friction measurements in the temperature range of 20–600 K. The results indicated that the appearance of the dislocation-induced relaxations strongly depends on the purity of the molybdenum, although the intrinsic dislocation relaxations appeared at about 100 K and 450 K in the high-purity molybdenum. The molybdenum containing a small amount of carbon did not exhibit the intrinsic dislocation relaxations but rather revealed a modulus increase due to the dislocation pinning caused by the dissolved carbon. When the molybdenum containing a small amount of carbon was annealed up to 700 K, a new relaxation peak appeared at about 450 K. The activation process for this relaxation indicated that it could be attributed to the relaxation due to a carbon-dislocation interaction. In addition, it was shown that the dislocation-induced relaxations in medium-purity molybdenum were small, which was attributed to the residual substitutional impurities in the molybdenum.

Silver cluster formation in ion-exchanged waveguides: processing technique and phenomenological model

1999 ◽  
Vol 253 (1-3) ◽  
pp. 261-267 ◽  
Author(s):  
E Borsella ◽  
G De Marchi ◽  
F Caccavale ◽  
F Gonella ◽  
G Mattei ◽  
...  
Keyword(s):  
Phenomenological Model ◽  
Cluster Formation ◽  
Silver Cluster ◽  
Processing Technique

Low frequency internal friction in zinc single crystals

1962 ◽  
Vol 10 (4) ◽  
pp. 430-441 ◽  
Author(s):  
J.M Roberts ◽  
N Brown
Keyword(s):  
Internal Friction ◽  
Single Crystals ◽  
Low Frequency

scholarly journals Brown Dwarf Companion Frequencies and Dynamical Interactions

2003 ◽  
Vol 211 ◽  
pp. 35-38
Author(s):  
Michael F. Sterzik ◽  
Richard H. Durisen
Keyword(s):  
Numerical Simulations ◽  
Cluster Formation ◽  
Low Frequency ◽  
Brown Dwarfs ◽  
Brown Dwarf ◽  
Multiple Star

Numerical simulations are used to explore how gravitational interactions within young multiple star systems may determine the binary properties of brown dwarfs. We compare different scenarios for cluster formation and decay and find that brown dwarf binaries, although possible, generally have a low frequency. We also discuss the frequencies of brown dwarf companions to normal stars expected from these models.

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