Integrated absorption coefficient

When it is known that Hqg varies appreciably within the tower, this term must be placed inside the integr in Eqs. (5-277) and (5-278) for accurate calculations of hf. For example, the packed-tower design equation in terms of the overall gas-phase mass-transfer coefficient for absorption would be expressed as follows ... 

In this expression the only variable is N0 and it is this which governs the extent of absorption. Thus it follows that the integrated absorption coefficient is directly proportional to the concentration of the absorbing species. 

It would appear that measurement of the integrated absorption coefficient should furnish an ideal method of quantitative analysis. In practice, however, the absolute measurement of the absorption coefficients of atomic spectral lines is extremely difficult. The natural line width of an atomic spectral line is about 10 5 nm, but owing to the influence of Doppler and pressure effects, the line is broadened to about 0.002 nm at flame temperatures of2000-3000 K. To measure the absorption coefficient of a line thus broadened would require a spectrometer with a resolving power of 500000. This difficulty was overcome by Walsh,41 who used a source of sharp emission lines with a much smaller half width than the absorption line, and the radiation frequency of which is centred on the absorption frequency. In this way, the absorption coefficient at the centre of the line, Kmax, may be measured. If the profile of the absorption line is assumed to be due only to Doppler broadening, then there is a relationship between Kmax and N0. Thus the only requirement of the spectrometer is that it shall be capable of isolating the required resonance line from all other lines emitted by the source. 

Fig. 21. Integrated intensity OH and OD bands versus time for adsorbed labeled propylene. CH3- CH=CD2 O, OH , OD. CD3—CH=CH2 A, OH A, OD. The integrated intensity for OD was multiplied by 1.35, the isotopic shift, in an attempt to correct for expected differences in the integrated absorption coefficient.

For more oareful identification of types of Lewis (aprotic) centres, CO adsorption was carried out in small doses (1-10 Jinol per cell) up to satiiration of active surface achieved. To reveal individual lines the separation of IR-spectra was carried out using CK-2 curve synthesiser. Concentration of aprotic centres was determined using coefficients of integral absorption from ref.[9J. The strength of aprotic centres was characterized by the heat of CO adsorbtion according to eq. (2). Concentration of Bronsted (pro-... 

Figure 3.3a). The total area under the curve gives the integrated absorption intensity, J ej [Pg.63]

A totally allowed transition has oscillator strength /=1 and molar extinction coefficient 105. Different factors may reduce the / values to different extents. Oscillator strengths / are related to integrated absorption intensities by the expression... 

Table 3.1. Binary integrated absorption coefficients of rare gas mixtures.

Table 3.2. Ternary integrated absorption coefficients of the translational band. Measurement from [95] calculation [296],...

In the framework of the impact approximation of pressure broadening, the shape of an ordinary, allowed line is a Lorentzian. At low gas densities the profile would be sharp. With increasing pressure, the peak decreases linearly with density and the Lorentzian broadens in such a way that the area under the curve remains constant. This is more or less what we see in Fig. 3.36 at low enough density. Above a certain density, the l i(0) line shows an anomalous dispersion shape and finally turns upside down. The asymmetry of the profile increases with increasing density [258, 264, 345]. Besides the Ri(j) lines, we see of course also a purely collision-induced background, which arises from the other induced dipole components which do not interfere with the allowed lines its intensity varies as density squared in the low-density limit. In the Qi(j) lines, the intercollisional dip of absorption is clearly seen at low densities, it may be thought to arise from three-body collisional processes. The spectral moments and the integrated absorption coefficient thus show terms of a linear, quadratic and cubic density dependence,... 

In the vacuum ultraviolet absorption bands in the region 1280 to 1600 A correspond to the fourth positive system A1 n-X L+. The absorption cross sections of this system are given in Fig. V-7. Since the widths of the CO rotational lines are much smaller than the instrumental resolution ( 10 cm" 1), it is not possible to obtain the absorption cross section of each rotational line [see Section 1-8 for details]. Thus, the cross sections shown in Fig. V-7 are much less than the true cross sections. An estimate of the integrated absorption coefficient of the (0,0) band is 1.7 x 104cm-latm-1 (899). Various electronic states and transitions are given in Fig. V-8. 

I 8 1 The Ifccr-Lambcrl Law in the Molecular System, 41 I 8.2 Deviation from the Beer-Lamberl Law, 42 I 8.3 Measurement of the Integrated Absorption Coefficient, 44... 

The ionization of NO by the Lyman-a line is the main source of ions in the D region. The photodissociation of NO in the upper atmosphere occurs from the /t2Z + (F > 4), B2n (c > 7), and C2n (F > 0). The dissociation rate of NO by the solar radiation is proportional to the integrated absorption coefficient of various bands (that is, the oscillator strength). From Table V 4 it can be seen that absorption by the /if (12,0) and 6 bands is most important in leading to photodissociation. 

The Schumann-Runge bands converge to the limit at 1750 A corresponding to the production of Of3/3) + Of1/)). The integrated absorption coefficients of the Schumann-Runge system from (0,0) to (20,0) have been... 

As with N02, the observed radiative lifetime of the A 1Bl state of S02 (4 x 10"5 sec) is much longer than the value calculated from the integrated absorption coefficient (2 x 10" 7 sec)229. This is again presumably due to strong interaction with the electronic ground state203. 

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