Conditions, absorbing

Condition/ Absorbance of the liberated iodine-starch complex for different durations... 

Here we are interested in escape out of the domain L specified by a single cycle of the potential that is out of a domain of length n that is the domain of the well. Because the bistable potential of Eq. (5.42) has a maximum at x = n/2 and minima at x = 0, x = 7t, it will be convenient to take our domain as the interval —7t/2 < x < n/2. Thus we will impose absorbing boundaries at x = —n/2, x = n/2. Next we shall impose a second condition that all particles are initially located at the bottom of the potential well so that x0 = 0. The first boundary condition (absorbing barriers at —n/2, n/2) implies that only odd terms in p in the Fourier series will contribute to Y (x). While the second ensures that only the cosine terms in the series will contribute because there is a null set of initial values for the sine terms. Hence... 

The nature of a surface will depend upon which atoms are exposed. For example, the surface of a crystal with the sodium chloride structure might consist of a mixture of atoms, as on 100 (Fig. 3.34a), or of just one atom type, as on 111 (Fig. 3.34b and 3.34c). However, it must be remembered that no surface is clean and uncontaminated unless it is prepared under very carefully controlled conditions. Absorbed gases, especially water vapor, are invariably present on a surface in air, which leads to changes in chemical and physical properties. 

Barium chloride under ordinary conditions absorbs gaseous ammonia very slowly, but under pressure it absorbs considerable quantities of ammonia gas, which is very quickly lost on exposure to air. 

An electronically excited molecule may, under some conditions, absorb another quantum and be raised to a higher excited state. Usually the population of excited species is so low that the probability of this occurrence is very slight. However, in recent years the technique of flash photolysis has been developed, which allows us to investigate the absorption properties of excited states. An extremely high intensity laser, which has approximately one million times the power of a conventional spectroscopic lamp, is turned on for a tiny fraction of a second, and a large population of excited species is produced. Immediately after this photolysis flash is turned off, a low-power spectroscopic flash may be turned on and the absorption spectrum of the already-excited system determined. By varying the delay between photolysis and spectroscopic flashes, much can be learned about the absorption and lifetime of singlet and triplet excited states. 

Fig. 4. v(CH) range of different epoxysilanes SA-layers on silica prepared under ambient conditions (absorbance given in Kubelka-Munk units). 

Another very important reason is that GeoDeck has a low water absorption index, compared to many other composite materials. For example, pressure-treated lumber absorbs 24% of water being immersed into water for 24 h. Trex absorbs 4.3% water in the same conditions (sanded surface) and 1.7% (unsanded surface), according to their own published data. The latter figure was confirmed in our studies (1.8%). GeoDeck in the same conditions absorbs only 1.0% of water (brushed surface). The less the water in the material, the less is the chance for microorganisms to get in and proliferate. Microbes need water for their life cycle. 

Light energy is passed efficiently from PE to PC to APC to photosystem I or II (Fig. 1). The amounts of PE and PC in the cell may vary, depending on the light conditions. Absorbance maxima of PE are in the range 498-568 nm, while PC absorbs around 625 nm, and APC at 618-673 nm. The relative amounts of PE and PC are determined by the spectral characteristics of the available light in redder light, more PC is present. The total phycobiliproteins may amount to 60 % of the soluble protein in the cell. 

Systemer exposed to ambient conditions absorbs moisture which has to be removed before further processing. Predrying should be done at 80°C for 48 hoixrs under vacuum. Under these conditions, the initial moisture of 0.79 to 1.06 was reduced to 0.09 to 0.11%. Processing methods are given in Table 2. 

Using this concept, Burdett developed a method in 1955 to obtain the concentrations in mono-, di- and polynuclear aromatics in gas oils from the absorbances measured at 197, 220 and 260 nm, with the condition that sulfur content be less than 1%. Knowledge of the average molecular weight enables the calculation of weight per cent from mole per cent. As with all methods based on statistical sampling from a population, this method is applicable only in the region used in the study extrapolation is not advised and usually leads to erroneous results. 

On metals in particular, the dependence of the radiation absorption by surface species on the orientation of the electrical vector can be fiilly exploited by using one of the several polarization techniques developed over the past few decades [27, 28, 29 and 30], The idea behind all those approaches is to acquire the p-to-s polarized light intensity ratio during each single IR interferometer scan since the adsorbate only absorbs the p-polarized component, that spectral ratio provides absorbance infonnation for the surface species exclusively. Polarization-modulation mediods provide the added advantage of being able to discriminate between the signals due to adsorbates and those from gas or liquid molecules. Thanks to this, RAIRS data on species chemisorbed on metals have been successfidly acquired in situ under catalytic conditions [31], and even in electrochemical cells [32]. 

With M = He, experimeuts were carried out between 255 K aud 273 K with a few millibar NO2 at total pressures between 300 mbar aud 200 bar. Temperature jumps on the order of 1 K were effected by pulsed irradiation (< 1 pS) with a CO2 laser at 9.2- 9.6pm aud with SiF or perfluorocyclobutaue as primary IR absorbers (< 1 mbar). Under these conditions, the dissociation of N2O4 occurs within the irradiated volume on a time scale of a few hundred microseconds. NO2 aud N2O4 were monitored simultaneously by recording the time-dependent UV absorption signal at 420 run aud 253 run, respectively. The recombination rate constant can be obtained from the effective first-order relaxation time, A derivation analogous to (equation (B2.5.9). equation (B2.5.10). equation (B2.5.11) and equation (B2.5.12)) yield... 

Neuhauser D and Baer M 1989 The time dependent Schrodinger equation application of absorbing boundary conditions J. Chem. Phys. 90 4351... 

Mandelshtam V A and Taylor H S 1995 A simple recursion polynomial expansion of the Green s function with absorbing boundary conditions. Application to the reactive scattering J. Chem. Phys. 102... 

Seideman T and Miller W H 1992 Quantum mechanical reaction probabilities via a discrete variable representation-absorbing boundary condition Green function J. Chem. Phys. 97 2499... 

The light emitted in the spontaneous recombination process can leave tire semiconductor, be absorbed or cause additional transitions by stimulating electrons in tire CB to make a transition to tire VB. In tliis stimulated recombination process anotlier photon is emitted. The rate of stimulated emission is governed by a detailed balance between absorjDtion, and spontaneous and stimulated emission rates. Stimulated emission occurs when tire probability of a photon causing a transition of an electron from tire CB to VB witli tire emission of anotlier photon is greater tlian that for tire upward transition of an electron from tire VB to tire CB upon absorjDtion of tire photon. These rates are commonly described in tenns of Einstein s H and 5 coefficients [8, 43]. For semiconductors, tliere is a simple condition describing tire carrier density necessary for stimulated emission, or lasing. This carrier density is known as... 

We can sample the energy density of radiation p(v, T) within a chamber at a fixed temperature T (essentially an oven or furnace) by opening a tiny transparent window in the chamber wall so as to let a little radiation out. The amount of radiation sampled must be very small so as not to disturb the equilibrium condition inside the chamber. When this is done at many different frequencies v, the blackbody spectrum is obtained. When the temperature is changed, the area under the spechal curve is greater or smaller and the curve is displaced on the frequency axis but its shape remains essentially the same. The chamber is called a blackbody because, from the point of view of an observer within the chamber, radiation lost through the aperture to the universe is perfectly absorbed the probability of a photon finding its way from the universe back through the aperture into the chamber is zero. 

Deliquescence and efflorescence. A substance is said to deliquesce (Latin to become liquid) when it forms a solution or liquid phase upon standing in the air. The essential condition is that the vapour pressure of the saturated solution of the highest hydrate at the ordinary temperature should be less than the partial pressure of the aqueous vapour in the atmosphere. Water will be absorbed by the substance, which gradually liquefies to a saturated solution water vapour will continue to be absorbed by the latter until an unsaturated solution, having the same vapour pressure as the partial pressure of water vapour in the air, is formed. In order that the vapour pressure of the saturated solution may be sufficiently low, the substance must be extremely soluble in water, and it is only such substances (e.g., calcium chloride, zinc chloride and potassium hydroxide) that deliquesce. 

Just as it is with laundry, drying often follows washing and is used to rid the solvent of any water that it absorbed. All solvents absorb some water although you can t see it. It is a good idea to rid the solvent/product of any water, especially before distillation, because it s one less thing to worry about and because there is an off-chance that water may form a slight amount of byproduct when heated with product oil under distillation conditions. 

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