Kinetics of Thermal Activation of an Ultraviolet Cone Pigment

2014 ◽  
Vol 137 (1) ◽  
pp. 307-313 ◽  
Author(s):  
Victoria Mooney ◽  
Sivakumar Sekharan ◽  
Jian Liu ◽  
Ying Guo ◽  
Victor S. Batista ◽  
...  
Keyword(s):  
Thermal Activation ◽  
Cone Pigment ◽  
Kinetics Of

scholarly journals Исследование с помощью молекулярной динамики образования димеров на поверхности (001) GaAs при низких температурах

2021 ◽  
Vol 55 (2) ◽  
pp. 134
Author(s):  
Н.Д. Прасолов ◽  
А.А. Гуткин ◽  
П.Н. Брунков
Keyword(s):  
Potential Energy ◽  
Thermal Activation ◽  
Average Rate ◽  
Temperature Reconstruction ◽  
Temperature Range ◽  
Quantum Mechanical Theory ◽  
Bond Order Potential ◽  
A Chain ◽  
Kinetics Of ◽  
Dynamics Method

The simulation of dimers formation during the low-temperature reconstruction of GaAs (001) surface terminated with Ga or As atoms was performed by the molecular dynamics method using the analytical Bond-Order Potential based on quantum mechanical theory incorporating both σ- and π- bonds between atoms. A decrease in values of potential energy of the atoms during formation of isolated surface dimer have been determined. It has been found that potential energy of an atom in As-dimer is several tenths of an eV lower than in Ga-dimer. Kinetics of the initial stages of Ga-dimers formation in the temperature range of 25 - 40 K was studied. It was found that the characteristic thermal activation energy of single isolated Ga-dimers formation is ~ 29 meV, which is lower than the same value for As-dimers (~ 38 meV). Time constants characterizing the average rate of transformation of one dimer into a chain of two dimers at temperature range of 28 - 37 K were estimated. Inverse values of these parameters for paired Ga- and As-dimers are in the ranges of 10^11 – 10^12 s^-1 and 10^9 – 10^10 s^-1, respectively, while corresponding parameters for the formation of single dimers are in the ranges of 4·10^6 – 10^8 s^-1 and 1.4·10^6 – 7.4·10^7 s^-1.

scholarly journals Dark Adaptation and Visual Pigment Regeneration in Human Cones

1973 ◽  
Vol 62 (4) ◽  
pp. 430-447 ◽  
Author(s):  
M. Hollins ◽  
M. Alpern
Keyword(s):  
Entire Range ◽  
Threshold Elevation ◽  
Monomolecular Reaction ◽  
Bright Flash ◽  
Wide Range ◽  
Cone Pigment ◽  
Normal Man ◽  
Low Threshold ◽  
Kinetics Of ◽  
Direct Proportionality

Foveal threshold elevation and red-green cone pigment regeneration have been studied in the dark after a wide range of bleaches in normal man with a view to probing the limits of the application of the Dowling-Rushton relation: i.e., the direct proportionality between log threshold elevation and fraction of unregenerated pigment. Cone pigment regeneration (and threshold recovery) is much faster after short bleaches than expected from the kinetics of a simple monomolecular reaction. Recovery is faster after a fixed (short) duration bleach the weaker it is. Except for the first 30 s after relatively weak bleaches and the entire recovery after a very brief (<0.001 s) saturating bright flash which bleaches a little more than 50%, the results are accurately fit by the Dowling-Rushton relation over the entire range tested with only one arbitrary constant (the proportionality factor). Theory predicts too low threshold in comparison with what is obtained, for both of these exceptions

Recovery Kinetics of Phosphorus Ion-Implanted a-Si:H

1996 ◽  
Vol 420 ◽  
Author(s):  
J. Nakata ◽  
S. Wagner ◽  
H. Gleskova ◽  
P. A. Stolk ◽  
J. M. Poate
Keyword(s):  
Gas Phase ◽  
Thermal Activation ◽  
Urbach Energy ◽  
Defect Density ◽  
Strained Si ◽  
Effective Electron ◽  
Additional Illumination ◽  
Hydrogenated Amorphous ◽  
Kinetics Of ◽  
Strained Bonds

AbstractHydrogenated amorphous silicon was implanted with phosphorus ions to a uniform concentration of 3×1020 cm-3 and defect saturation. The implants were annealed isochronally up to 400°C in the dark or under additional illumination. This illumination had no effect on recovery. The Urbach energy remains higher than that of silicon-implants. The midgap defect density anneals to ˜ 1018 cm-3, typical of gas-phase doped samples. The dark conductvity remains lower and its thermal activation energy higher than in gas-phase doped samples. We surmise that the Si-Si network absorbs some of the donor electron-induced defect density by forming strained Si-Si bonds. These strained bonds widen the band tails, and thus reduce the effective electron mobility and pin the Fermi level.

Magnetocaloric Properties of MnBi Compound as a Function of Grain Size

2016 ◽  
Vol 257 ◽  
pp. 143-146
Author(s):  
Carmen Curcio ◽  
Elena S. Olivetti ◽  
Luca Martino ◽  
Michaela Küpferling ◽  
Vittorio Basso
Keyword(s):  
Grain Size ◽  
Thermal Activation ◽  
Structural Transition ◽  
Permanent Magnets ◽  
Activation Volume ◽  
Entropy Change ◽  
Transformation Kinetics ◽  
Magnetocaloric Properties ◽  
Different Grain Size ◽  
Kinetics Of

MnBi is a magnetic material with many peculiar properties, interesting for different applications such as rare-earth-free permanent magnets and magnetic refrigeration. In this work the entropy change and the transformation kinetics of the magneto-structural transition are investigated, for two sets of samples with different grain size (“as-annealed” and “compacted pwd”). Both sets show a logarithm dependence on the temperature scan rate of the transition temperature upon cooling. This suggests that thermal activation effects are present. The estimated activation volume v0 of the magneto-structural transition corresponds to around 120 atoms.

Effect of Thermal Activation on the Kinetics of Cd2+Ions Sorption by AlPO4

2009 ◽  
Vol 44 (2) ◽  
pp. 304-315 ◽  
Author(s):  
Syed Mustafa ◽  
Muhammad Javid ◽  
Muhammad Iqbal Zaman
Keyword(s):  
Thermal Activation ◽  
Kinetics Of

The photolysis of solid potassium azide

1952 ◽  
Vol 215 (1121) ◽  
pp. 254-265 ◽  
Keyword(s):  
Activation Energy ◽  
Potassium Salt ◽  
Thermal Activation ◽  
Thermal Activation Energy ◽  
Experimental Measurements ◽  
Ionic Conductance ◽  
Potassium Azide ◽  
Cation Sites ◽  
Kinetics Of

Experimental measurements of photoconductance in potassium and barium azides and of the kinetics of photolysis of the potassium salt are reported. The theory previously advanced to explain the photodecomposition of barium azide is confirmed and extended by a calculation of the probable lifetime of a trapped exciton. Ionic conductance measurements enable the exciton traps to be identified with vacant cation sites and it is pointed out that the thermal activation energy required for the decomposition of the double trapped excitons is governed by steric considerations.

scholarly journals Cellular automata simulation for high temperature austenite grain growth based on thermal activation theory and curvature-driven mechanism

2016 ◽  
Vol 94 (12) ◽  
pp. 1353-1364 ◽  
Author(s):  
Min Wang ◽  
Yajun Yin ◽  
Jianxin Zhou ◽  
Hai Nan ◽  
Tong Wang ◽  
...  
Keyword(s):  
High Temperature ◽  
Grain Growth ◽  
Thermal Activation ◽  
Growth Exponent ◽  
Austenite Grain ◽  
Activation Theory ◽  
Different Temperatures ◽  
Curvature Driven ◽  
Austenite Grain Growth ◽  
Kinetics Of

Based on the thermal activation theory and curvature-driven mechanism, a 2D cellular automaton model with different state transition rules was built. Validity of the model was proved by the shrinking of circular grains. Grain growth of high temperature austenite was simulated by this model; the morphology, grain size distribution, topological aspects, and local kinetics of austenite grain growth were analyzed under different simulation time. Among the grains with different sides, the 6-sided grains are the most common and 5-sided grains are the second most common. The grains with more than six sides will grow and grains with less than six sides will shrink, while the 6-sided grains will neither grow nor shrink. The kinetics of normal grain growth follows the Burke equation and the growth exponent at different temperatures and activation energies has been researched.

Sign in / Sign up

Export Citation Format

Share Document