Charge-transfer oscillator strength

PCT charge-transfer oscillator strength mcan measured lifetime... 

Inelastic collisions of swift, charged particles with matter are completely described by the distribution of generalized oscillator strengths (GOS s) characterizing the collision. These quantities, characteristic of excitation in the N-electron target (or, in fact, of a dressed projectile as well [1]) from some initial state 0) to a final state n) and concomitant momentum transfer, can be written... 

Molecular structures for CNDO/S calculations were optimized using HP/3-21G shown in Fig, 1, Dominant charge transfers at some selected states and their oscillator strength " /l(E-30 esu). 

The dipole oscillator strength is the dominant factor in dipole-allowed transitions, as in photoabsorption. Bethe (1930) showed that for charged-particle impact, the transition probability is proportional to the matrix elements of the operator exp(ik r), where ftk is the momentum transfer. Thus, in collision with fast charged particles where k r is small, the process is again controlled by dipole oscillator strength (see Sects. 2.3.4 and 4.5). 

When located at opposite ends (or at conjugated positions) in a molecular system, a donor and an acceptor do more than simply add up their separate effects. A cooperative phenomenon shows up, involving the entire disubstituted molecule, known as charge transfer (C.T.). Such compounds are colored (from pale yellow to red, absorption from 3,000 to 5,000 A) and show high U.V. absorption oscillator strength. "Figure 2 helps understand the enhancement of optical nonlinearity in such a system. 

The shorter wavelength bands (200-300 mp) could be similar (but less forbidden) charge-transfer transitions or homoannular ring-localized transitions. For instance, Nesmeyanov10 concludes, from an inspection of oscillator strengths, that the strong 200 mp band is a -n -s- tt transition in the ring. 

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