Angstrom units

Angstrom unit, A A unit of length equivalent to 10" cm, (10 °m). Used to describe molecular and lattice dimensions and wavelengths of visible light. 

At the outset, we were faced with the difficult decision whether to use the Angstrom unit or the nanometre for the dimensions of molecules. After careful consideration, we have come down firmly in favour of the Angstrom and we believe that this decision will meet with the approval of the majority of our readers. When quoting graphs and tables of data from the literature, we have retained the original units (kcal, Torr, C, tonin, etc.) in the belief that it is more reasonable to state the data in the form used by the original author—except where comparisons are being made between results presented in different units. 

Because of commercial usage. Angstrom units are shown here. To convert to nm, divide by 10. 

Angstrom units Inches 3.937 X 1Q- Calories, gram Joules 4.1868... 

Angstrom units Meters 1 X 10- Calories, gram Liter-atmospheres 4.1.30 X 10"-... 

Angstrom units Microns 1 X 10" Calories, gram Horsepower-hours 1.5591 X 10- ... 

Molecular modelling calculations using values of smaller than 3 Angstrom units for these proton-proton distances can be performed to obtain an optimized picture of the molecule. But this exceeds the scope of this book. 

A.E., abbrev. (Angstromeinheit) Angstrom unit, Ae-. for words beginning Ae- see also A-. 

Angstrom unit (A), definition, 307 Antimony, determination by x-ray emission spectrography, 328 in silicate, determination by absorption-edge method, 140 in solution, determination by absorption-edge method, 140 Aperture, relative, of x-ray optical system, 113... 

Hyperfiltration (Reverse Osmosis) is a form of membrane distillation or desalination (desalting) operating with membrane pore sizes of perhaps 1 to 10 Angstrom units. The various individual RO component technologies have improved tremendously over the last 20 to 25 years, and resistance to fouling and permeate output rates have benefited. Nevertheless, all RO plants remain susceptible to the risk of fouling, and adequate pretreatment and operation is essential to minimize this problem. 

For steel, passivation is achieved by the surface formation of a tough, adherent mixture of oxides. The passive film is primarily gamma-magnetite (y-Fe203) but also contains gamma-hydrated ferric oxide (y-FeOOH). The film thickness is perhaps 15 A to 30 A (angstrom units). 

A AA/AMPS angstrom unit aciylic acid/2-aciylamido-2-methyl propane sulfonic acid copolymer... 

Fig. 77.—Gaussian density distribution of the chain displacement vec tors for chain molecules consisting of 10 freely jointed segments, each of length 1 = 2.5 A. The end-to-end length r is in Angstrom units and W(x, y, z) is expressed in A". ...

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