Alkemade lines

In this case, the Alkemade line C-AB does not cross die boundary curve ef) between these primary phases. Now, we state the Alkemade theorem in a more general form ... 

The direction of falling temperature on the boundary curve of two intersecting primary phase areas is always away from die Alkemade line. 

If die Alkemade line intersects the boundary curve, the point of intersection represents a temperature maximum on the boundary curve. 

If the Alkemade line does not intersect die boundary curve, then temperature maximum on the curve is represented by that end which if prolonged would intersect the Alkemade line. 

Alkemade lines are also called in many different ways including conjugation lines and joins. Both Alkemade lines and Alkemade triangles (composition triangles produced by Alkemade lines) are of use in die understanding of ternary systems. They play an essential role in understanding crystallisation or heating paths ... 

Alkemade line intersects the boundary curve, the point of intersection represents a temperature maximum on the boundary curve. If the Alkemade line does not intersect the boundary curve, then the maximum on the boundary curve is represented by that end which, if prolonged, would intersect the Alkemade line (Levin et al., 1964). 

Jongerius MJ, Van Bergen ARD, Hollander T, Alkemade CTH (1981) An experimental study of the collisional broadening of the Na-D lines by Ar, N2 and H2 perturbers in flames and vapor cells—I. The line core. J Quant Spectrosc Radiat Transfer 25 1-18... 

Atomic absorption spectroscopy is the term used when the radiation absorbed by atoms is measured. The application of AAS to analytical problems was considerably delayed because of the apparent need for very high resolution to make quantitative measurements. In 1953, Walsh brilliantly overcame this obstacle by the use of a line source, an idea pursued independently by Alkemade, his work being published in 1955. 

Figure 24-1 9 Emission spectrum of a brine sample obtained with an oxyhydrogen flame. The spectrum consists of the superimposed line, band, and continuum spectra of the constituents of the sample. The characteristic wavelengths of the species contributing to the spectrum are listed beside each feature. (R. Hermann and C. T. J. Alkemade, Chemical Analysis by Flame Photometry, 2nd ed., p. 484. New York Interscience, 1979.)...

Flame atomic absorption spectroscopy (AAS) is currently the most widely used of all the atomic methods listed in Table 28-1 because of its simplicity, effectiveness, and relatively low cost. The technique was introduced in 1955 by Walsh in Australia and by Alkemade and Milatz in Holland. The first commercial atomic absorption (AA) spectrometer was introduced in 1959, and use of the technique grew explosively after that. Atomic absorption methods were not widely used until that time because of problems created by the very narrow widths of atomic absorption lines, as discussed in Section 28A-1. 

FIGURE 6-4 A portion of the flame emission speclrum for sodium, 800 ppm in naphtha isopropanol oxyhydrogen flame slit 0.02 mm. Note Chat the scale is expanded in the upper trace and flame conditions were changed to reveal greater detail for Na lines, but not for molecular bands. Note also that the lines at 589.00 and 589.59 nm are off scale in the upper trace. (Adapted from C. T. J. Alkemade and R. Herrmann, Fundamentdis oMna/yfrca/ Flams Specfroscopy, p. 229, New York Wiley. 1979, with permission.)... 

Figure 3.6 Compatibility triangles (dashed lines) superimposed on the stability fields 1 to 10, and directions of falling temperatures on the phase boundary curves (arrowheads), determined according to the Alkemade theorem.

Figure 3.26 Cotectic (compatibility) triangles (solid lines) in the ternary diagram Ca0-Al203-Si02 (mass%). In the Si02-rich portion, three important triple points are indicated at the intersection of the phase boundaries (dashed lines). The arrows show the direction of falling temperatures according to the Alkemade theorem...

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