Optical constants of water

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. 

Studies of dielectric spectra of water in a range of temperatures present a fundamental physical problem that has also important practical applications. Experimental investigation of these spectra has a rich history. We refer here only to a few works. In Downing and Williams [22] and Zelsmann [21] tables for optical constants of water were presented for the temperature T = 300 K and for a wide T-range, respectively. In recent publications by Vij et al. [32] and Zasetsky et al. [33] in addition to original investigations the results of many other works are also discussed. In work by Liebe et. al. [19] a useful empirical double Debye-double Lorentz formula for the complex permittivity e(v, T) is suggested. 

Figure 1.15. External reflection. Influence of angle of incidence on (a, b) mean-square electric fields (E ) and (c, d) normalized mean-square electric fields (E )sec >i at 1000 cm" inside model organic layer 5 nm thick (02 = 1.5 and k2 =0.1) located at boundaries (a, c)air-Si (solid line) and water-Si (dashed line) and b, d) air-water. Optical constants of water and Si indicated in Table 1.1.

IR optical constants of water and lubricants using IR elhpsometiy combined with an ATR cell. Thin Solid Films, 313-314 (1998) 718-721. 

Bertie JE, Lan Z. 1996. Infrared intensities of liquids. XX The intensity of the OH stretching band of liquid water revisited, and the best current values of the optical constants of H20(I) at 25 °C between 15,000 and 1 cm . Appl Spectrosc 50 1047-1057. 

The optical properties of water have been studied for centuries the modern results are scattered throughout the literature of many scientific fields. Fortunately, several authors have critically surveyed the literature on H20 and have assembled collections of optical constants for broad wavelength ranges. I hese reviews include those by Irvine and Pollack (1968), Hale and Querry... 

Figure 10.3 Dielectric functions of water (Hale and Querry, 1973). c" for ice is taken partly from Irvine and Pollack (1968) and partly from an unpublished compilation of the optical constants of ice, from far ultraviolet to radio wavelengths, by Stephen Warren (to be submitted to Applied Optics).

There are numerous properties of materials which can be used as measures of composition, e.g. preferential adsorption of components (as in chromatography), absorption of electromagnetic waves (infra-red, ultra-violet, etc.), refractive index, pH, density, etc. In many cases, however, the property will not give a unique result if there are more than two components, e.g. there may be a number of different compositions of a particular ternary liquid mixture which will have the same refractive index or will exhibit the same infra-red radiation absorption characteristics. Other difficulties can make a particular physical property unsuitable as a measure of composition for a particular system, e.g. the dielectric constant cannot be used if water is present as the dielectric constant of water is very much greater than that of most other liquids. Instruments containing optical systems (e.g. refractometers) and/or electromechanical feedback systems (e.g. some infra-red analysers) can be sensitive to mechanical vibration. In cases where it is not practicable to measure composition directly, then indirect or inferential means of obtaining a measurement which itself is a function of composition may be employed (e.g. the use of boiling temperature in a distillation column as a measure of the liquid composition—see Section 7.3.1). 

Appendix 1. Calculation of Fourier Amplitudes b -i for Librators Appendix 2. Transformation of Integral for Spectral Function of Precessors Appendix 3. Optical Constants of Liquid Water... 

In Table IX we present the list of optical constant of ordinary (H20) water [42] at 27°C covering very wide range of frequencies (from 10 cm-1 until 1000 cm-1). For two other temperatures (1°C and 50°C) we present in Table X such constants recorded in Ref. 53 for a narrower region from 400 cm-1 to 820 cm-1. Both tables comprise the absorption maximum of the librational band, and the first one includes also the maximum in the R-band. For lower frequencies we can use the empirical formulas of Liebe et al. [17], They are represented in Section G.2.a. Note that the absorption coefficient a is determined by the imaginary component... 

Waals envelope of the solvent. This projection can be expressed in terms of a response function, whose kernel contains a damping factor (the dielectric constant ) very near to the optical dielectric constant of water, eopt, when the water molecules are held fixed, or rapidly increasing towards the static dielectric constant, when water molecular motions are allowed and their number in the cluster increases. This is the origin of our PCM model (more details can be found in Tomasi, 1982). Surely, similar considerations spurred Rivail and coworkers to elaborate their SCRF method (Rivail and Rinaldi, 1976). An additional contribution to the formulation of today continuum models came from the nice analysis given by Kolos (Kolos, 1979 dementi et al., 1980) of the importance of dispersion contributions. 

To provide a better understanding of the relationship between reflectance and the optical constants of the contacting media, some calculated values of reflectances at v = 1000 cm for interfaces of air. Si, -GaP, water, and A1 are given in Fig. 1.11. The optical constants of these four media, which were used in the calculations, are tabulated in Table 1.1. 

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