Transition amplitude, state specific

In a collision system such as an atom A colliding with a diatomic molecule BC, one is interested in the transition amplitudes, or S-matrix elements, which describe transitions between specific quantum states of the molecule BC. From the S-matrix elements one can construct scattering amplitudes for any collision process resulting from A + BC, the square modulus of the amplitudes being the cross sections. 

Equation (4) yields also an expression for the half-scattering state specific transition amplitude from initial state p.c > ... 

Before we get specific, consider another type of spectroscopy, namely Raman scattering. When one excited surface (i.e., one excited electronic state) contributes, the amplitude for making a transition to state n on the lower potential surface from a state 0, also on the lower surface, is (suppressing polarization indices)... 

In order to obviate the dependence of our conclusions upon any specific partial wave amplitude, the amplitudes were contracted into two sets those expected from 3py ionization and those not. Ionization of a dimer 3py Rydberg state via a y-polarized transition would, in an atomic A/ 1 picture of Rydberg orbital ionization, produce only electrons with, va, d , <7g character. Therefore, the ratio of. va I dG + dother contributions Y,pfg is a measure of 3py Rydberg character in the (NO)2 excited electronic states. In Fig. 28 (bottom), we plot the time dependence of this ratio, labeled the 3py signal , showing that... 

From magnetic resonance spectroscopy [49] it is well-known that IB effects are adequately circumvented by the tricks of a spin echo experiment. For instance, in a two-pulse echo experiment, IB effects are averaged out and one probes spin dephasing determined by time-dependent fluctuations characteristic of HB only (and not IB). More specifically, a nll-r-n microwave pulse sequence is applied, where the first nil pulse creates a coherent superposition state for which a la = 1 and the n pulse, applied at time r after the first pulse, generates a spin coherence (the echo) at time 2r after the initial pulse. The echo amplitude is traced with r. The echo amplitude decay time is characteristic of the pure dephasing dynamics. For phosphorescent triplet states it is possible to make the echo optically detectable by means of a final nil probe pulse applied at time f after the second pulse [44]. In Fig. 3b, the optically detected echo amplitude decay for the zero-field transition at 2320 MHz of... 

In order to verify that the PSII-beta is specifically responsible for the 100 ps PSII lifetime component observed at Fo conditions, we performed experiments to close PSII-beta but leave PSII-alpha open. It has been shown that PSII-beta is only weakly coupled to the plasto-quinone pool so that in the absence of DCMU it is possible to create a state, Fpl, in which the PSII-alpha centers are predominantly open but most PSII-beta centers are closed (7). If the fast, 100 ps, signal at Fo is really a composite of PSI and open PSII-beta centers then the amplitude of this signal should diminish during the Fo - Fpl transition but be constant afterwards. Fig 3a,b,c shows that such behavior is observed during the Fo - Fpl - Fm transition. 

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