Absorption coefficient of water

The fitting to the data in Figs. 5.7 and 5.8 gives the values of oqlbs to about 5% precision. The value found for the bare sphere is consistent with the values found at other pressures and for overcoupled modes. Using (5.14) and the known bulk absorption coefficient of water (at these wavelengths, water has ab 800 m l)14 we estimate <5 6.7 pm from Fig. 5.7. This corresponds to water coverage on the... 

Figure 7.1 The absorption coefficient of water as a function of the frequency of the electromagnetic radiation. Adapted from Jackson, 1975. (See Colour Plate 1)...

Mie calculations with the optical constants of water given in Fig. 10.3 are shown in Fig. 11.3 extinction and absorption are plotted logarithmically, photon energy linearly. The bulk absorption coefficient of water is shown in Fig. 11.3 c. Because many of the extinction features of water and MgO, both of which are insulators, are similar, we present calculations for a single water droplet (in air) with radius 1.0 jam. Size-dependent spectral feature.4 are therefore not obscured as they are for a distribution of radii. 

Fig. VI —I. Absorption coefficients of water in the vacuum ultraviolet region. k is given in units of atm-.1 cm"base e, 0°C. From Watanabe and Zelikotf (1016), reprinted by permission. Copyright 1953 by the American Institute of Physics.

The absorption spectrum of water in the vacuum ultraviolet has been studied by Johns (533) and by Bell (92). Sharp rotational structure has been observed only below 1240 A (533). The 1240 A bands have been assigned to the 1 Bx —, 4, transition and is the lirst member of the Rydberg scries. The absorption coefficients of water in the vacuum ultraviolet have been measured by Watanabe ct al. (1016, 1018) and arc shown in Fig. VI I. The absorption coefficients of D2C) have been measured by Laufcr and McNesby in the region 1300 to 1800 A (601). 

Laufer, A.M., and J.R. McNesby, Deuterium isotope effect in vacuum ultraviolet absorption coefficients of water and methane. Canad J Chem f3, 3487, 1965. 

Watanabe, K., and M. Zelikoff, Absorption coefficient of water vapor in the vacuum ultraviolet. J Opt Soc Amer 43, 753, 1953. 

The absorbed dose buildup factor B(r) in Equation 8 is the ratio of the actual dose in the dosimeter at a point P, r cm. from a point isotropic 60Co source imbedded in large water container, to the dose that would be measured at the same point if there were no scattered radiation. In this equation I0 is the energy emitted by the source Zs is the scattered radiation flux at P m is the total absorption coefficient of water (0.0632... 

Absorption coefficients of water and a typical human tissue (aorta) as a function of wavelength. The suitable region for optical excitation is between 650 and 1000 nm. This figure is drawn using data from the Handbook on Industrial Laser Safety, http //info.tuwien.ac.at/iflt/safety/index.htm. 

One sees in Heitler s book that the absorption coefficient of water for 7-rays of about 5 MeV (which are hardest to absorb) is. 03. A shield of 110 cm gives a 6 = 3 for (2), permitting an about 6.5 cm decrease of the thickness of the Pb to be used. On the other hand, the lead shield also guards against neutrons. According to Friedman s report (C-99), the total cross section of Pb is about 6 X 10 cm for fast neutrons, of which 3.6 is due to inelastic scattering. This gives. 19 for the macroscopic absorption coefficient of lead for fast neutrons and the presence of 13.5 cm lead should permit one to decrease the thickness of the water layer to 105 cm. 

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