Quantum requirement

A value (symbolized by (f>) equal to the number of molecules transformed via a reaction per quantum of light absorbed. It is synonymous to quantum efficiency and is the reciprocal of the quantum requirement. 

QUANTUM MECHANICAL TUNNELING CHEMICAL KINETICS HYDROGEN TUNNELING KINETIC ISOTOPE EFFECTS QUANTUM REQUIREMENT QUANTUM YIELD QUANTUM YIELD FLUQRESCENCE ACTINOMETER Quasi-axial,... 

Measurement of Quantum Yield, Quantum Requirement, and Energetic Efficiency of the 02-Evolving System of Photosynthesis by a Simple Dye Reaction 127... 

If one assumes that the ratio H /e is 2, then an ATP/2 e of 1.66 can be calculated. Izawa and Good [91] (see also Ref. 92) have established that a ratio ATP/2 e of 2 can be calculated for phosphorylating electron transport, if one subtracts the independently occuring electron transport rate observed in the absence of ADP-Pji obviously, such a correction cannot be made if the purpose is to evaluate the quantum requirement of photosynthesis, but it is important in the investigation of the efficiency of energy coupling. 

Warthmann, R., Pfennig, N. and Cypionka, H. (1993). The quantum requirement for H2 production by anoxygenic phototrophic bacteria. Appl. Microbiol. Biotechnol. 39, 358-362. 

The quantum requirements for both P700 photooxidation and P430 photoreduction were measured in PS-I particles using monochromatic light sources for excitation With 671-nm excitation light, the quan-... 

As two light reactions are necessary for the electron transport from H20 to NADP+ and four positive charges generated by photoelectric generator Cu are required for water oxidation, a minimal quantum requirement of 8 h-vjOj should be observed. The experimental data of 8—10 h v per 02124 are in excellent agreement with the theoretical value. 

Fig. 3. (A) The irradiance response curve of CO2 assimilation under non-photorespiratory conditions (350 ppm CO2,2% O2, andN2- The solid line represents the response as it would be if the quantum yield for CO2 fixation remained at a maximum value. Excess irradiance (quanta which cannot be used for photochemistry) is a consequence of the loss of quantum yield for CO2 fixation shown by the difference between the actual and maximum responses. (B) The irradiance dependencies of the quantum requirement for CO2 fixation ( ) and CO2 fixation (O) for a leaf of Juanulloa auremtiaca.

Under conditions of low photorespiration, about 90% of photochemical product is allocated to COj fixation. The progression from light limitation to light saturation in photosynthesis is illustrated in Pig. 3 A which shows a typical light saturation curve for photosynthesis illustrated in the shmb Juanulloa aurantiaca. The quantum requirement per mole COj fixed (on an incident irradiance basis) increases as the irradiance and rate of CO2 assimilation increase. The higher the flux the lower the efficiency of COj assimilation (Fig. 3B). As the ATP and NADPH requirements for COj fixation are independent of... 

Phonon velocity is constant and is the speed of sound for acoustic phonons. The only temperature dependence comes from the heat capacity. Since at low temperature, photons and phonons behave very similarly, the energy density of phonons follows the Stefan-Boltzmann relation oT lvs, where o is the Stefan-Boltzmann constant for phonons. Hence, the heat capacity follows as C T3 since it is the temperature derivative of the energy density. However, this T3 behavior prevails only below the Debye temperature which is defined as 0B = h( DlkB. The Debye temperature is a fictitious temperature which is characteristic of the material since it involves the upper cutoff frequency ooD which is related to the chemical bond strength and the mass of the atoms. The temperature range below the Debye temperature can be thought as the quantum requirement for phonons, whereas above the Debye temperature the heat capacity follows the classical Dulong-Petit law, C = 3t)/cb [2,4] where T is the number density of atoms. The thermal conductivity well below the Debye temperature shows the T3 behavior and is often called the Casimir limit. 

Although Eq. (2.10) fulfils the relativistic condition of space-time equivalence, it does not fulfil the quantum requirement of linearity so that the superposition principle, probability density formula and uncertainty principle could apply [5,6]. The third step was to look for an analogous equation linear in all that is,... 

Under optimal conditions in the laboratory at low photon flux density a photon requirement (or quantum requirement) of 9 for O2 production or CO2 fixation, however, is rarely measured. The most reaHstic assumption of the minimal quantum requirement seems to be a value of 10. This is based on an analysis of dedicated research in this field oxygen exchange measurements with leaf-disc electrodes for higher plants (Bjdrkman and Demmig, 1987 Evans, 1987) laser-induced oxygen flash yield measurements (Dubinsky et al, 1986 Ley and MauzeraU, 1982) and photoacoustic and photothermal calorimetry, as reflected upon by Malkin and Fork (1996). 

A quantum requirement of 10 thus means that the maximal yield of sugar (CH2O) on photons is equal to 0.10. This number vtiU be called the maximal yield of sugar on photons V7/ph,m with unit mols molph This parameter will be very important later when describing photoautotrophic growth in a mathematical model. 

Ley AC, Mauzerall DC Absolute absorption cross-sections for photosystem II and the minimum quantum requirement for photosynthesis in Chtoretta vulgaris, Biochim Biophys Acta Bioenerg 680(1) 95-106, 1982. 

Quantum requirements were calculated from the slope at the linear part of the curve Control(o) PPT lh( ), 5h(A)... 

Fig.8 Diurnal variation of quantum requirement of photosynthesis in bamboo leaf...

Table 4. The apparent quantum requirement of photosynthesis measured at places of different altitude...

Table 5 The effect of atmospheric pressure and gas composition on the apparent quantum requirement of photosynthesis In wheat leaves...

However, one should not overlook the possibility that Pigment System 2 is capable of transferring two electrons from water to X" or plastoquinone, for example, with only one quantum. In this case, the quantum requirement for transfer of four electrons through the two light reactions would be 4 -f- 2 = 6. If we recall that the free energy change corresponding to Reaction (3) was... 

Quantum efficiency, quantum yield see Quantum requirement. 

Quantum requirement the number of light quanta required for the formation of one molecule of O2 in Photosynthesis (see). Two quanta are required per electron. The theoretical value of Q.r. is eight, since the production of one molecule of Oj proceeds according to the following equation, with transfer of four electrons from water (see Photolysis of water) to NADP+ 2H2O ->02 + 4H+ + 4e. The experimentally determined value of Q. r. lies between 8 and 10 for leaves, and between 10 and 14 for isolated chloro-plasts. It is influenced by the physiological state of the experimental system. 

Quantum yield, quantum effciency see Quantum requirement. 

As with any other class of matter, if an energy gap in a complex compound matches the energy of an incident photon, absorption occurs. In many coordination compounds, the quantum required for excitation from the ground state is of visible light, so that these compounds are of many colors, often of great beauty. Two chief selection rules decide which of all the possible transitions occur ... 

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