Rate of emission from

The rate of absorption from state 1 to state 2 is N B12p(v), where p(y) is the energy density incident on the sample at frequency v. The rate of emission from state 2 to state 1 is N2[A2i + B2 p(v). At equilibrium, these two rates are equal, hence... 

Emissions inventories are typically obtained by combining the rate of emissions from various sources (the emission factors ) with the number of each type of source and the time over which the emissions occur. 

The excited-state wavepacket spontaneously emits photons while undergoing transitions to any of the electronically-ground vibrational wavefunctions t (where we have lumped the final state quantum numbers i>/, jf in a single index f). The rate of emission from a given 4% component of the excited wavepacket to a given ground state is given in terms of the Einstein A-coefficient [9],... 

With reduction of pressure the mean free path grows larger, and with it the resistance to mass transfer due to intermolecular collision is progressively diminished. At pressures corresponding to mean free paths larger than the dimensions of the vessel in question, the gas phase resistance to mass transfer is negligible and the only limiting factor on the rate of material movement is the rate of emission from the interface. 

Whereas the various estimates for NH3 production from animals are reasonably consistent, it is evident from Table 9-3 that the rate of emissions from soils is essentially unknown. A scarcity of field observations exists... 

The rate of emission from area dAi must equal the rate at which energy is received by the total area Ax, since all the radiation from dA impinges on some part of Ax-The rate of reception by A2 is found by integrating dq A over area Ax-Hence,... 

To calculate the expected fluorescence anisotropy, we now evaluate the rate of fluorescence with frequency v and polarization ep following excitation with polarization e,. Because we are interested in the initial rate of radiative transitions from state 2 to state 1, we can setpn to zero in Eq. (10.79). The density matrix elements P22 and P22 can be obtained from Eqs. (10.75a-10.75d, 10.76a, and 10.76b). Averaging over aU orientations then gives the initial rate of emission from state 2 ... 

Formation of emissions from fluidised-bed combustion is considerably different from that associated with grate-fired systems. Flyash generation is a design parameter, and typically >90% of all soHds are removed from the system as flyash. SO2 and HCl are controlled by reactions with calcium in the bed, where the lime-stone fed to the bed first calcines to CaO and CO2, and then the lime reacts with sulfur dioxide and oxygen, or with hydrogen chloride, to form calcium sulfate and calcium chloride, respectively. SO2 and HCl capture rates of 70—90% are readily achieved with fluidi2ed beds. The limestone in the bed plus the very low combustion temperatures inhibit conversion of fuel N to NO. ... 

The problem of emissivity from real materials has stimulated the study of pyrometers that measure radiation at two different wavelengths. The principle of the two-color pyrometer is that the energy radiated from a source of one wavelength increases with temperature at a rate different from that radiated at another wavelength. Thus temperature can be deduced from the ratio of the intensities at the two wavelengths, regardless of emissivity. Two-color pyrometers are not widely used. 

Another factor influencing contaminant and heat transfer from dirty to clean zones against the stable airflow is a turbulent exchange between these zones. This process should be considered in the design of displacement or natural ventilation systems and evaluation of the emission rate of contaminants from the encapsulated process equipment (Fig. 7.111a). 

The rate of emission of sulfur dioxide is first calculated from... 

Luminescence lifetimes are measured by analyzing the rate of emission decay after pulsed excitation or by analyzing the phase shift and demodulation of emission from chromophores excited by an amplitude-modulated light source. Improvements in this type of instrumentation now allow luminescence lifetimes to be routinely measured accurately to nanosecond resolution, and there are increasing reports of picosecond resolution. In addition, several individual lifetimes can be resolved from a mixture of chromophores, allowing identification of different components that might have almost identical absorption and emission features. 

Estimates also were made for 65 coke plants in 12 states. Coke ovens produce benzene as a by-product, but not all of it can be recovered. It has been estimated that benzene contributes about two-thirds of one percent of the coal gas generated. Potential points of emissions from one type of coke battery are illustrated in Figure 7. Emissions from coke ovens were derived from estimated emission factors (based on coke oven product assays and benzene yields) and coal charging rates. 

Organic solvents enhance emitted intensities mainly because of a higher resultant flame temperature (water has a cooling effect), a more rapid rate of feed into the flame because of the generally lower viscosity, and the formation of smaller droplets in the aerosol because of reduced surface tension. The resultant enhancement of spectral line intensity may be 3-to over 100-fold. Conversely, the presence of salts, acids and other dissolved species will depress the intensity of emission from the analyte and underlines the need for careful matching of samples and standards. 

Winer AM, Arey J, Atkinson R, et al. 1992. Emission rates of organics from vegetation in California s Central valley. Atmos Environ 26A(14) 2647-2659. 

Some lasers produce a continuous-wave (CW) beam, where the timescale of the output cycle is of the same order as the time taken to remove photons from the system. CW lasers can be modified to produce a pulsed output, whereas other lasers are inherently pulsed due to the relative rates of the pumping and emission processes. For example, if the rate of decay from the upper laser level is greater than the rate of pumping then a population inversion cannot be maintained and pulsed operation occurs. 

Due to its gaseous nature it may have an effect on the stratospheric ozone layer [281, 402, 404]. After injection into soil for fumigation, methyl bromide rapidly diffuses through the soil pore space to the soil surface and then into the atmosphere [159,162,163,405,406]. Since a plastic sheet typically covers the soil surface, the rate of emission into the atmosphere depends upon the thickness and density of the plastic, if other conditions are the same [159, 406]. Other routes of disappearance from soil include chemical hydrolysis, methylation to soil organic matter through free radical reactions, and microbial degradation [ 136,159,405,407]. Several reports appeared on the study of the microbial transformations of methyl bromide, summarized as follows ... 

To agree to standardise odour measurement techniques to enable quantitative measurements of emission rates of odour from different livestock production systems. 

There are different time scales associated with the various emissions and uptake processes. Two terms that are frequently used are turnover time and response or adjustment) time. The turnover time is defined as the ratio of the mass of the gas in the atmosphere to its total rate of removal from the atmosphere. The response or adjustment time, on the other hand, is the decay time for a compound emitted into the atmosphere as an instantaneous pulse. If the removal can be described as a first-order process, i.e., the rate of removal is proportional to the concentration and the constant of proportionality remains the same, the turnover and the response times are approximately equal. However, this is not the case if the parameter relating the removal rate and the concentration is not constant. They are also not equal if the gas exchanges between several different reservoirs, as is the case for C02. For example, the turnover time for C02 in the atmosphere is about 4 years because of the rapid uptake by the oceans and terrestrial biosphere, but the response time is about 100 years because of the time it takes for C02 in the ocean surface layer to be taken up into the deep ocean. A pulse of C02 emitted into the atmosphere is expected to decay more rapidly over the first decade or so and then more gradually over the next century. 

If the excitation occurred at a low temperature such that the thermal emission rate of carriers from traps is very small, the perturbed equilibrium will exist for a long time and only upon an appropriate increase of the sample temperature can the relaxation process proceed at a rate that permits one to monitor it by measuring the conductivity a(T) = exp(ncfin + Pl p) of the sample (TSC) or the luminescence (TSL) emitted by radiative recombination of carriers thermally released from the traps. 

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