The P—O bond in (CII3)sPO has been reported to be well described as a double bond, since the 13C—H coupling constant of this compound is closer to that of (CH3)3P than to that of (CHa) P+ (31). [Pg.194]

It was also shown that Hbcp expressed as a double exponential is proportional to the interaction potential (U(i ) = JTIbcp(J )), where/was estimated to be the force constant of the O- H hydrogen bond in ice VIII from the values of the local energy densities at the equilibrium O- -H separation [95]. [Pg.460]

The hypothesis of pure precession (Van Vleck, 1929) is often used in the estimation of A-doubling constants. These constants, in the o,p, q notation suggested by Mulliken and Christy (1931), are introduced into the effective Hamiltonian [Pg.327]

Example 4.3. Seawater in Equilibrium with the Atmosphere (pco2 — 10 atm) Constmct a double logarithmic diagram—similar to that of Figure 4.5 for seawater (35%o salinity). At 20°C the following constant can be used [Pg.162]

The first line in this expression describes the rotational structure with color spin-doubling and the hyperflne interaction of the effective electron spin S with the nuclear spin I. B is the rotational constant, J is the electron-rotational angular momentum, A is the o -doubling constant. The second line describes the interaction of the molecule with the external fields B and E, (A is the unit vector directed from the heavy nucleus to the light one). The last line corresponds to the P-odd electromagnetic interaction of the electrons with the anapole moment of the nucleus described by the constant /ca [40], P,T-odd interaction of the electron EDM de with the interamolecular field, and P,T-odd scalar interactions of the electrons with the heavy nucleus [90]. [Pg.271]

It is seen that the values of kd are very close. Hence, the reaction of POOH with the C—H bond is not the main initiation reaction. If the breakdown is a monomolecular process, the rate of O—O bond homolysis in polymer must be close to that in the gas phase. 2,2-Dimethylethyl hydroperoxide breaks down in the gas phase with a rate constant of 1.6 x 1013 exp(— 158/i 7) = 5.3 x 10 x s 1 (398 K, [4]), that is, by four orders of magnitude more slowly than in polymer. Hence, the decomposition reactions in the polymers are much faster than the monomolecular homolysis of peroxide. Decomposition reactions may be of three types (see Chapter 4), such as the reaction of POOH with a double bond [Pg.472]

Rpar is a double precision work array, and Ipar is an integer work array. These are provided so that DDAPLUS can pass special information to the user-provided subroutines. The parameters whose sensitivity coefficients are desired must be stored in the Rpar array in the locations specified by the elements l,.Nspar of the array Ipar. For example, the input Ipar(2)=3 would indicate that the second sensitivity parameter was stored in Rpar(3). The location Ipar(O) is reserved for a user-defined constant, such as the address (later in Ipar) of a list of pointers to other information. The location Rpar(O) may be used to store values of a user-defined continuation parameter. [Pg.200]

For the LSV and CV techniques, the concept of reversibility/irreversibility is therefore very important. Electrochemists are responsible for some confusion about the term irreversible, since a reaction may be electrochemically irreversible, yet chemically reversible. In electrochemistry, the term irreversible is used in a double sense, to describe effects from both homogeneous and heterogeneous reactions. In both cases, the irreversible situation arises when deviations from the Nernst equation can be seen as fast changes in the electrode potential, E, are attempted and the apparent heterogeneous rate constants, /capp, for the O/R redox couple is relatively small. The heterogeneous rate constant can be split into two parts a constant factor in terms of the standard rate constant, k°, and an exponential function of the overpotential E - Eq), as expressed in Eq. 59, where only the reductive process is considered (see also Eq. 5). [Pg.520]

Similar equations for o,p, and q may be derived for generalized pure precession situations involving two or more open shells. The validity of these pure precession equations depends on many assumptions, yet experimentalists are very quick to use them to explain the sign or even the magnitude of observed A-doubling and spin-rotation constants or to use these constants to infer /eff values for valence-shell a and 7r orbitals. [Pg.331]

See also in sourсe #XX -- [ Pg.330 , Pg.618 ]

© 2019 chempedia.info