Resolution index

The ability of a chromatographic process to separate or resolve two similar compounds (Figure 3.10) is measured as the resolution index (Rs). 

The resolution index (Rs) is a measure of the ability of a separation process to separate two similar substances. 

The efficiency of a column can be assessed in a similar manner to that described for HPLC and values for the resolution index of two solutes, the number of theoretical plates and the height equivalent to a theoretical plate may also be calculated. Although it is easier to measure gas pressure, it is the actual gas flow, which is affected by the particle size and compression of the packing, that should be used in column assessment investigations. 

Synthetic polymers possess the molecular weight distribution which also broadens the peak width. To avoid the incorporation of this extra broadening effect in the calculation of the resolution, two additional parameters have been introduced the resolution index [ref. 2], Rj, and the specific resolution [ref. 3], Rgp,... 

A much better way would be to use phase contrast, rather than attenuation contrast, since the phase change, due to changes in index of refraction, can be up to 1000 times larger than the change in amplitude. However, phase contrast techniques require the disposal of monochromatic X-ray sources, such as synchrotrons, combined with special optics, such as double crystal monochromatics and interferometers [2]. Recently [3] it has been shown that one can also obtain phase contrast by using a polychromatic X-ray source provided the source size and detector resolution are small enough to maintain sufficient spatial coherence. 

The second choice is a simpler solution. According to Sarko and Muggli,66 all 39 observed reflections in the Valonia X-ray pattern are indexable by a two-chain triclinic unit cell with a = 9.41, b =8.15 and c = 10.34 A, a = 90°, 3 = 57.5°, and y = 96.2°. Ramie cellulose, on the other hand, is completely consistent with the two-chain monoclinic unit cell. Also, there are significant differences between their high-resolution solid-state l3C NMR spectra, indicating that Valonia and ramie celluloses, the two most crystalline forms, reflect two distinct families of biosynthesis. On this basis, the Valonia triclinic and the ramie monoclinic forms are classified69 as Ia and Ip, respectively. It has been shown from a systematic analysis of the NMR spectra by these authors, and from electron-dif-... 

The Advanced-Very-High-Resolution Radiometer (AVHRR) carried on board the NOAA-7 satellite has been collecting radiance data from the earth s surface since 1978. The polar-orbiting satellite records global data on a neardaily basis. The 4-kilometer data have been remapped by NO A A into monthly composites. The data are collected in 2 bands-one visible (VIS), the other near infrared (NIR). The Normalized Difference Vegetation Index, or NDVI, defined... 

Fung, I. Y., Tucker, C. J. and Prentice, K. C. (1987). Application of Advanced Very High Resolution Radiometer vegetation index to study atmosphere-biosphere exchange of CO2, /. Geophys. Res. 92, 2999-3015. 

Hall GL, Whitehead WE, Mourer CR, et al. 1986. A new gas chromatographic retention index for pesticides and related compounds. J High Resolut Chromatogr Commun 9 266-271. 

The resolution of the instrument in the vertical direction depends upon the wavelength of visible light (450 to 850 nm), the oil refractive index, and the difference between the maximum and the minimum interference intensity as follows [5,18] ... 

Fig. 8—Resolution of film thickness versus optical interference intensity [4,5], (a) different wavelengths, (b) different refractive indexes.

In addition, combining the microscope with the use of a pulsed laser light source provides temporal information on these systems in a small domain. The dispersion of refractive index, however, strongly affects the temporal resolution in the measurements of dynamics under the microscope and typical resolution stays around 100 fs when a Ti Sapphire laser is used as an excitation source. 

FIG. 20-24 High -resolution TEM image of Si nanowires produced at 500 C and 24.1 MPa in supercritical hexane from gold seed crystals. Inset Electron diffraction pattern indexed for the <111> zone axis of Si indicates <110> growth direction. [Reprinted with permission from Lu et al. Nano Lett., 3(1), 93-99 (2003). Copyright 2003 American Chemical Society. ]... 

---