Kinetic energy radical structures

In addition to its role with regard to chemical reactivity, 7(r) is also linked to atomic shell structure and electronegativity, local temperature (or kinetic energy), radical characterization, bond strain and local polarizability. For a recent overall review, see Politzer and Murray. ... 

The structure of the radical cation [CaHsN] (102) has been established by mass-analyzed ion kinetic energy spectrometry (MIKE) (780MS518). From structure (103), structures (104) and (105) are formed (Scheme 4). 

The stabilization of the radical cation by forming a polaron is a trade-off between its delocalization and the energy required to distort the DNA structure. The former lowers the kinetic energy of the intrinsically quantum mechanical migrating radical cation, and the latter will be determined by factors that are independent of specific base sequence, such as the force constants of bonds in the sugar diphosphate backbone. 

Photoelectron spectroscopy (PES) is also carried out in the gas phase photons of known energy (E/,v), for example, the He(I) line (21.21 eV), ionize a substrate the kinetic energy (Eyn) of the emitted electrons is measured and the vertical ionization potentials (/y) derived (Eq. 13). The PES provides information on the energies of occupied molecular orbitals (MOs) " the highest occupied molecular orbital (HOMO) of the parent reveals the bond(s) likely to be weakened or broken upon ionization. The PES data reflect the geometries of the parent molecule and need not have any bearing on the equilibrium structure of the radical cation. 

More precise information about the details of such anomalous radical eliminations resulted from the detailed investigation of labelled compounds of the general structure 45 51. Here the combined application of different methods e.g., appearance potential measurements, peak shape analysis, CA studies, kinetic energy release) established that the cleavage of a heteroatom-carbon bond can take place via two fundamentally different mechanisms ... 

By plotting ln[Irem/(/ I J + 1)] versus ] (J + 1) for a series of rotational lines a so-called rotational temperature can be determined. It characterizes the kinetic energy of the molecules and radicals, by which the band spectra are emitted. It is also a good approximation of the temperature reflecting the kinetic energy of the neutrals and ions in a plasma. For the case of a hollow cathode discharge the Boltzmann plot and the temperatures as measured from CN and N) band hyper-fine structures are given in Fig. 3. 

Figure 17.1 TOF spectrum of H atoms, produced from the photodissodation (at A = 211.51 nm (top) and A = 211.75 nm (bottom)) of jet-cooled C2H2, using the Rydberg tog gyng technique. The rotationally resolved structure yields detailedinformation on theenergy distribution in theC2H(X) fragment and also provides information on the absolute structure of this free-radical. Note that the horizontal axis has been converted to show the H atom total kinetic energy release. Adapted from Mordaunteto/, J. Chem. Phys., 1998, 108 519, with permission of the American Institute of Physics...

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