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Topic: Quantum yield

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phottran.htm Normalization of the quantum yields with respect to the limiting quantum yield for each wavelength yields identical solvent dependence curves for both complexes indicating that the solvent dependence is independent of the wavelength dependence. A similar wavelength change led to only a slight increase in quantum yield when the solvent was toluene. In both complexes, the quantum yield increased with increasing concentration of CHCl www.ucalgary.ca /~chlangfo/phottran.htm

Radiation Chemistry and Photochemistry The exponential dependence of quantum yield on excitation energy is explained by the expected distribution of trap depths in the neat liquid. The quantum efficiency of this reaction was shown to correlate with the difference in the ionization potentials (IP) of the solvent and the aromatic solute; for high-IP aromatic hydrocarbons, the quantum yield of the hole injection may approach 0.5. Although these yields correlate with the exothermicity of the hole transfer, it appears that geminate pair dynamics is more important than the energetics. chemistry.anl.gov /photochemistry/part-a.html   (2664 words)

Quantum dot - Wikipedia, the free encyclopedia To this end, Quantum Dots have quickly filled in the role, being found to be superior to traditional organic dyes on several counts, one of the most immediately obvious being brightness (owing to the high quantum yield) as well as their stability. Quantum dots are particularly significant for optical applications due to their theoretically high quantum yield. In semiconductors, quantum dots are small regions of one material buried in another with a larger band gap. en.wikipedia.org /wiki/Quantum_dots   (1484 words)

Radiation Chemistry and Photochemistry Quantum yield for production of solvated electrons in water photolysis as a function of excitation energy (two-photon and one-photon). The quantum efficiency of this reaction was shown to correlate with the difference in the ionization potentials (IP) of the solvent and the aromatic solute; for high-IP aromatic hydrocarbons, the quantum yield of the hole injection may approach 0.5. We determined the major features of this reaction in nonpolar (cycloalkanes) and polar (water, alcohols, polyols, and ethers) solvents and used this knowledge to study the photophysics of laser-induced photoionization of aromatic molecules in these solvents. www.chm.anl.gov /photochemistry/part-a.html   (1484 words)

44_4 quantum yield of photosynthesis, bio-optical modelling, primary production, environmental factors The model makes it possible to determine the quantum yield from known values of these environmental factors. Manuscript received 19 September 2002, reviewed 21 October 2002, accepted 30 October 2002. www.iopan.gda.pl /oceanologia/44_4.html   (1484 words)

Quantum entanglement - Wikipedia, the free encyclopedia This occurs for two subtle reasons: (i) quantum mechanical measurements yield probabilistic results, and (ii) the no cloning theorem forbids the statistical inspection of entangled quantum states. Quantum entanglement is the basis for emerging technologies such as quantum computing and quantum cryptography, and has been used for experiments in quantum teleportation. Quantum entanglement is a quantum mechanical phenomenon in which the quantum states of two or more objects have to be described with reference to each other, even though the individual objects may be spatially separated. en.wikipedia.org /wiki/Quantum_entanglement   (1455 words)

Quantum dot - Wikipedia, the free encyclopedia To this end, Quantum Dots have quickly filled in the role, being found to be superior to traditional organic dyes on several counts, one of the most immediately obvious being brightness (owing to the high quantum yield) as well as their stability. Self-assembled quantum dots nucleate spontaneously under certain conditions during molecular beam epitaxy when a material is grown on a substrate to which it is not lattice matched. These quantum dots confine electrons, holes, or electron-hole pairs (so-called excitons) to zero dimensions (Compare to quantum wires (confined to a line) and quantum wells (confined to a planar region)) to a region on the order of the electrons' de Broglie wavelength. en.wikipedia.org /wiki/Quantum_dot   (1214 words)

Quantum logic counts on geometry TRN 072501 This idea of computing by geometry is at the heart of a proposed scheme for quantum computing that could yield prototype systems that are sturdier and easier to control than experimental computers based on previous schemes, which involve manipulating the energy levels of particles. Quantum computers could solve certain types of very large problems almost instantaneously because quantum bits, or qubits, can represent every possible solution to a problem and quantum computers can check every possibility in relatively few steps. Quantum bits perform geometric computations by walking through parameter space, said Duan. www.trnmag.com /Stories/072501/Quantum_logic_counts_on_geometry_072501.html   (1214 words)

Quantum Entanglement and Information Quantum entanglement is a physical resource, like energy, associated with the peculiar nonclassical correlations that are possible between separated quantum systems. Quantum information can be processed, but the accessibility of this information is limited by the Holevo bound. The impossibility of copying an unknown quantum state, or a state that is known to belong to a set of nonorthogonal states with a certain probability, and the existence of a trade-off relation between information gain and state disturbance, is the basis of the application of quantum information to cryptography. plato.stanford.edu /entries/qt-entangle   (1214 words)

International Radiation Detectors: UVG: Quantum Yield Owing to their 100% collection efficiency, the external quantum efficiency of UVG-series photodiodes can be calculated in the UV and short wavelength visible (about 160 nm to 600 nm) as the product of the quantum yield times one minus the reflectance of the photodiode. Recently, 1 cm^2 active area UVG series diodes were used to determine quantum yield (number of electron-hole pairs generated per absorbed photon) of silicon in 254 nm to 160 nm spectral region [1]. Quantum yield in this region has been determined for the first time and is shown in Fig. www.ird-inc.com /uvgqua.html   (1214 words)

quantumredshift This is achieved by imposing a quantum condition on the second of the two equations governing the behaviour of the Bohr atom (the orbital energy equation). Therefore Corollary 2 states: Within a quantum interval, atomic quantities that are affected by smooth changes in the properties of the physical vacuum will vary in such a way that energy is conserved. This statement by French therefore implies that, within a quantum interval with changing c, and hence f, the rate of revolution of the electron in its orbit will also be proportional to c. www.setterfield.org /quantumredshift.htm   (9041 words)

How to Measure a Production Quantum Yield Always run a "blank" of your solvent and calibrate your spectrophotometer. by the comparative method using a reference in a different solvent, but solvent differences in both refractive index and radiative rate constant must be taken into account. Tip : A problem frequently arises when a solvent is used for which there is no well-established reference. qf.iqs.url.es /singlet_oxygen/howto_fd.htm   (9041 words)

The Energetic Vacuum: Implications For Energy Research Although this is true in a certain sense (it is the source of quantum noise), by and large the homogeneity and isotropy (uniformity) of the ZPF distribution prevent naive observation, and only departures from uniformity yield overtly observable effects. The quantum vacuum is a very active place, with all sorts of particles appearing and disappearing. In quantum theory, however, this is not the case. www.ldolphin.org /energetic.html   (3270 words)

Photosensor with enhanced quantum efficiency - Patent 4822748 A low quantum yield is measured where the device is thick and recombination is high due to the p.sup.+ layer 23. Such a naturally produced oxide film, called native oxide, has been used successfully in promoting the quantum efficiency of a CCD imaging sensor for blue, ultraviolet, far ultraviolet and low energy x-ray wavelengths, but it increases the time necessary to fabricate devices from a few months to a few years which is an unacceptable delay. 7 is a graph of quantum efficiency at 4000.ANG. www.freepatentsonline.com /4822748.html   (3270 words)

Selected Abstracts From the combined quantum yield and lifetime measurements, knr is shown to decrease strongly with lowering temperature, by more than 2 orders of magnitude, and kf is shown to increase. These facts and the comparison with quantum chemical calculations for planar and twisted structures of 1 and 2 are interpreted as evidence for a photochemically re-ached low lying state with charge separation (Twisted Intra-molecular Charge Transfer, TICT), responsible for these fluorescence losses and especially active for 2. Quantum chemical calculations indicate that several minima on the S1-hypersurface are responsible for this behaviour. www.chemie.hu-berlin.de /wr/publications/literatur-abstracts.html   (3270 words)

U.S. Pregrant 20030076484 - Systems for CMOS-compatible three-dimensional image sensing using quantum efficiency modulation Photodetector quantum efficiency is modulated to process detected signals to yield data proportional to the distance z separating the target and photodetector. Quantum efficiency can be modulated with fixed or variable phase methods and may be enhanced using enhanced photocharge collection, differential modulation, and spatial and temporal multiplexing. A preferably CMOS-implementable system measures distance and/or brightness by illuminating a target with emitted optical energy having a modulated periodic waveform whose high frequency component may be idealized as S1=cos(??t). cxp.paterra.com /uspregrant20030076484.html   (3270 words)

quantumbogodynamics "quantum mechanical" "quantum number" "quantum, quanta" "quantum theory" "quantum yield" quondam Quaintness quandang Quandong Quantum "Quantum meruit" "Quantum suff" "Quantum sufficit" "Quantum valebat" Queendom Quindem Quinidine Quinoidine Quintain Quintan quintin Quintin Quintine Quondam quantum "quantum bogodynamics" "quantum cell" "quantum cell wire" "quantum computer" "quantum computing" "quantum dot" "quantum-dot cellular automata" dictionary-x.com /quantumbogodynamics.html   (222 words)

Laser Focus World - LANL quantum-dot technology available for licensing The new method of dynamic holography harnesses the absorptive properties of quantum dots to yield holographic gratings that have ultrafast response, high efficiencies, greatly improved photostability, and tunable optical properties. Quantum dots are chromophores that combine size-controlled emission colors and high emission efficiencies with excellent photostability and chemical flexibility. The LANL quantum-dot portfolio includes the use of quantum dots for a broad range of applications including lighting, solar energy, lasers, and coatings. lfw.pennnet.com /Articles/Article_Display.cfm?Section=OnlineArticles&SubSection=Display&PUBLICATION_ID=12&ARTICLE_ID=219061&pc=ENL   (679 words)

Quantum noise and quantum Langevin equations This latter can be handled by means of van Kampen's cumulant expansion to yield derivations of the quaiclassical Langevin equation, stochastic electrodynamics, quantum optical, and quantum Brownian motion master equations (under appropriate conditions). The result of Benguria and Kac—that the quantum Langevin equation yields the Boltzmann distribution over energy levels in thermodynamic equilibrium—is also verified. The quantum Langevin equation of Ford, Kac, and Mazur is rederived and shown to be equivalent to an adjoint equation. domino.research.ibm.com /tchjr/journalindex.nsf/4ac37cf0bdc4dd6a85256547004d47e1/22508f66e625c95f85256bfa0067f6ee?OpenDocument   (679 words)

On Going Past Statistical Quantum Mechanics - Ravi Gomatam Quantum indeterminism ultimately prevails at the level of individual observation, and thus it is widely felt that our understanding of the physical meaning of QT is still incomplete. Like any statistical theory, statistical quantum mechanics or SQM (the ψ function plus the Schrцdinger equation, interpreted via Born’s rule) is also silent about the individual outcome. This is compatible with the fact that Schrцdinger equation is itself a deterministic equation and hence must yield a definite prediction, at least in principle, despite the fact that the equation involves complex numbers in a fundamental way. www.bvinst.edu /gomatam/pub-2003-02.htm   (856 words)

Yavuz Nutku: List of publications Malykh A. Nutku and M. Sheftel `` Partner symmetries of the complex Monge-Ampere equation yield hyper-Kahler metrics without continuous symmetries " J. Phys. 1 Nutku, Y., ``Post-Newtonian equations of hydrodynamics in the Brans-Dicke theory" Ap. 2 Chandrasekhar, S. and Y. Nutku, ``The second post-Newtonian equations of hydrodynamics in general relativity" Ap. www.gursey.gov.tr /nutku/publist.html   (856 words)

dcheung01 The idea of an approximate quantum Fourier transform was first introduced by Coppersmith, who proposed that if the QFT could be sped up at expense of the accuracy of the algorithm, the trade-off may yield an improvement in the phase estimation algorithm. is not an integer multiple of 1/(2^n), the quantum phase estimation algorithm will return the nearest integer multiple of 1/(2^n) to This indicates that the difference between the AQFT and the QFT are negligible for sufficiently large n, and are essentially equivalent in performance. www.iqc.ca /science/dcheung01   (856 words)

Many Fates Resonance Zeno Clover Most other secondary parameters tested are found to have little effect on the scale and character of the results, with one important exception: studies performed using fully deterministic pseudorandom sources, either hard-wired or algorithmic, yield null overall mean shifts, and display no other anomalous features. If you are connected with something like a clover patch, you can select (maybe by Resonant Connections and the Quantum Zeno Effect and the Quantum Anti-Zeno Effect) which futures involve you and it, and so influence Fate. Although the absolute effect sizes are quite small, of the order of 10^(&endash;4) bits deviation per bit processed, over the huge databases accumulated the composite effect exceeds 7 sigma (p = 3.5 x 10^(&endash;13)). www.valdostamuseum.org /hamsmith/ManyFates.html   (2474 words)

Bell's Theorem It is important to note, however, that all entangled quantum states yield predictions in violation of Ineq. That Quantum Mechanics admits of such entangled states was discovered by Erwin Schrödinger (1926) in one of his pioneering papers, but the significance of this discovery was not emphasized until the paper of Einstein, Podolsky, and Rosen (1935). Therefore the incompatibility of Quantum Mechanics with this conceptual framework does not preclude the contextual hidden variables models proposed by Bell in (1966), an example of which is the de Broglie-Bohm model, but it does preclude models in which the contexts are required to be local. plato.stanford.edu /entries/bell-theorem   (2474 words)

Quantum Mechanics 4 The wave-particle duality that quantum mechanics entails has been given perhaps its most famous expression in Heisenberg's Uncertainty Principle. It is a basic property of nature, as described by quantum mechanics. We will sketch a proof of it, using the rules of quantum mechanics as we have discussed them. www.phy.duke.edu /courses/100/lectures/QM4/QM4.html   (960 words)

Quantum entanglement This occurs for two subtle reasons: (i) quantum mechanical measurements yield probabilityprobabilistic results, and (ii) the no cloning theorem/ forbids the statistical inspection of entangled quantum states. Quantum entanglement is a quantum mechanicsquantum mechanical phenomenon in which the quantum states of two or more objects have to be described with reference to each other, even though the individual objects may be spacespatially separated. Quantum entanglement is the basis for emerging technologytechnologies such as quantum computerquantum computing, quantum cryptography and has been used for experiments in quantum teleportation/. www.infothis.com /find/Quantum_entanglement   (1410 words)

2. Some Basic Ideas about Quantum Mechanics Whenever we make a measurement on a Quantum system, the results are dictated by the wavefunction at the time at which the measurement is made. Clearly therefore the measurement can only ever yield an eigenvalue (even though the original state was not an eigenfunction), and it will do so with a probability determined by the composition of the original superposition. Before the measurement is made the particle wavefunction is a superposition of several position eigenfunctions, each corresponding to a different possible position for the particle. newton.ex.ac.uk /research/qsystems/people/jenkins/mbody/mbody2.html   (2015 words)

Quantum Measurement In Quantum Measurement, editors Richard A. Healey and Geoffrey Hellman marshal the resources of leading physicists and philosophers of science, skillfully joining their insights and ingenuity to yield some of the most innovative and altogether promising thought to date on this enigmatic issue. What emerges from this careful synthesis is a theoretically powerful and energetic new approach to the measurement dilemma, one that furthers our conceptual understanding of the fundamental interconnections between micro- and macroscopic systems, and that strives, ultimately, to describe and define within a unified quantum mechanical framework the breadth of our physical reality. Some quantity such as position or momentum is always indefinite on a quantum system; and if an indefinite quantity is measured, the macroscopic state of the measuring apparatus that is supposed to record the outcome instead becomes indefinite itself. www.upress.umn.edu /Books/H/healey_quantum.html   (329 words)

pascazio.html If very frequent measurements are performed on a quantum system, in order to ascertain whether it is still in its initial state, transitions to other states are hindered and the quantum Zeno effect takes place. We give an *elementary* introduction to these issues and then recast the quantum Zeno effect in terms of the dynamical coupling to another quantum system: when the coupling is strong (or very frequent) the This continuing time evolution within the projected subspace is named "quantum Zeno dynamics" and has interesting features. www.fisica.unile.it /~gerardi/pascazio.html   (206 words)

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