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Symbols, Terminology, and Nomenclature
Published in W. M. Haynes, David R. Lide, Thomas J. Bruno, CRC Handbook of Chemistry and Physics, 2016
W. M. Haynes, David R. Lide, Thomas J. Bruno
Euler number (Eu) - A dimensionless quantity used in fluid mechanics, defined by Eu = p/v2, where p is pressure, is density, and v is velocity. [2] Eutectic - The point on a two-component solid-liquid phase diagram which represents the lowest melting point of any possible mixture. A liquid having the eutectic composition will freeze at a single temperature without change of composition. Excitance (M) - Radiant energy flux leaving an element of a surface divided by the area of that element. [1] Exciton - A localized excited state consisting of a bound electronhole pair in a molecular or ionic crystal. The exciton can propagate through the crystal. Exosphere - The outermost part of the earth's atmosphere, beginning at about 500 to 1000 km above the surface. It is characterized by densities so low that air molecules can escape into outer space. Expansion coefficient - See thermal expansion coefficient. Extended electron energy loss fine structure (EXELFS) - See Techniques for Materials Characterization, page 12-1. Extended x-ray absorption fine structure (EXAFS) - See Techniques for Materials Characterization, page 12-1. Extinction coefficient - See Absorption coefficient, molar. F-Center - See Color center. Fahrenheit temperature (°F) - The temperature scale based on the assignment of 32°F = 0 °C and a temperature interval of °F =(5/9)°C; i.e., t/°F = (9/5)t/°C + 32. Farad (F)* - The SI unit of electric capacitance, equal to C/V. [1] Faraday constant (F)* - The electric charge of 1 mol of singly charged positive ions; i.e., F = NAe, where NA is Avogadro's constant and e is the elementary charge. [1] Faraday effect* - The rotation of the plane of plane-polarized light by a medium placed in a magnetic field parallel to the direction of the light beam. The effect can be observed in solids, liquids, and gasses. Fatty acids - Aliphatic monocarboxylic acids derived from or contained in esterified form in an animal or vegetable fat, oil, or wax. Natural fatty acids commonly have a chain of 4 to 28 carbons (usually unbranched and even-numbered), which may be saturated or unsaturated. By extension, the term is sometimes used to embrace all acyclic aliphatic carboxylic acids. [5] Fermat's principle - The law that a ray of light traversing one or more media will follow a path which minimizes the time required to pass between two given points. Fermi (f) - Name sometimes used in nuclear physics for the femtometer. Fermi level - The highest energy of occupied states in a solid at zero temperature. Sometimes called Fermi energy. The Fermi surface is the surface in momentum space formed by electrons occupying the Fermi level. Fermi resonance - An effect observed in vibrational spectroscopy when an overtone of one fundamental vibration closely coincides in energy with another fundamental of the same symmetry species. It leads to a splitting of vibrational bands. Fermi-Dirac distribution - A modification of the Boltzmann distribution which takes into account the Pauli exclusion principle. The number of particles of energy E is proportional to [e(E-µ)/kT+1]-1 , where µ is a normalization constant, k the Boltzmann constant, and T the temperature. The distribution is applicable to a system of fermions.
High resolution FTIR spectroscopy of fluoroform 12CHF3 and critical analysis of the infrared spectrum from 25 to 1500 cm−1
Published in Molecular Physics, 2018
S. Albert, S. Bauerecker, E. S. Bekhtereva, I. B. Bolotova, H. Hollenstein, M. Quack, O. N. Ulenikov
CHF3 is an oblate symmetric top molecule (C3v point group) with three totally symmetric vibrations of A1 symmetry (ν1, ν2, ν3) and three doubly degenerate vibrations with E-symmetry. Table 1 provides a survey of the fundamentals as known today, ν2, ν5 and ν3 + ν6 have similar frequencies as do also 2ν3 and ν4. Furthermore ν1 is close to 2ν4, providing the basis for a pronounced resonance polyad structure of great complexity in the near infrared spectrum [6]. The rotationally resolved spectrum of CHF3 is still poorly understood in many ranges in spite of substantial previous work [3–7,10,14,16,32,33,39–61]. Bernstein and Herzberg [3] reported spectra in the near infrared region and proposed a two level Fermi-resonance in very early work already. Gilliam et al. measured its microwave spectra in 1949 [40]. The analysis of the spectra of fluoroform was extended after this early work by other authors at modest resolution, as well as at high resolution (Table 1, see also Section 5), and the results of ab initio calculations at different levels are available [17,24,25,28–32,51] (see also [62]). Recently, some lines in the CF3 stretching fundamental range were measured with very high precision using frequency comb assisted quantum cascade laser spectroscopy [63,64].