Scattering lifetime

To account the above scenarios, we follow Ref [78] that the observed Xspp actually consists of two components, namely, absorption and radiative scattering losses, and is given as 1/xgpp = 1/Xabs+1/Xscatt> where Xabs and Xscatt are absorption and radiative scattering lifetimes, respectively. With the fact that all the hole sizes... 

Intraband electronic transitions were also considered by Erskine and Stem (1973). Asymmetric scattering (lifetime ys) as well as normal electron scattering (lifetime t) were considered. In the high-frequency limit where tor > 1 and wys > 1 they find that the latter process dominates and gives rise to the following frequency... 

Many different models have been developed to describe the conductivity of (CH) c- Most of them are based on the assumption of some kind of hopping, and fail to fit the data for N-(CH)j . Conceptually, such models must be ruled out. For a quasi-one-dimensional metal the conductivity in the chain direct is (7 = e D(E= e D( p) F where D( f) is the state density at the Fermi energy, vp is the Fermi velocity, t is the back-scattering lifetime, and X is the mean-free path. D Ep)Vp = lna I fin, the conductivity can be expressed in terms of the conduction electron density, b, and the projection, a, of the C-C distance on the chain direction as... 

LMTO linearized muifin-tin ortntal T scattering lifetime... 

The magnetization or the magnetic susceptibility is the most common one of these physical quantities, and its periodic variation is called the de Haas-van Alphen (dHvA) effect (de Haas and van Alphen 1930, 1932). It provides one of the best tools for the investigation of Fermi surface properties such as the extremal cross-sectional area S, the cyclotron mass w and the scattering lifetime x of metals (Shoenberg 1984). Sometimes other physical quantities are also measured for example, torque, static strain, ultrasonic velocity, and magnetoresistance, etc. The last type of measurement is called the Shubnikov-de Haas effect. 

The relation between the effective mass m and the scattering lifetime T for the conduction electrons in metals is defined as follows ... 

Thus m /t is expected to be the same for two similar orbits with the same mean free path. When the effective mass m is enhanced by a factor of (1 -i- A) from spin fluctuations, eq. (65) indicates that r should also be enhanced by a factor of (1+A). This occurs because a large mass is translated into a small velocity from eq. (64) so that the scattering lifetime becomes (1 + A) times larger than that obtained by eq. (64) if the mean free path is the same. In terms of the Dingle temperature, eq. (65) becomes... 

Figure Al.6.15. Schematic diagram, showing the time-energy uncertainty principle operative in resonance Raman scattering. If the incident light is detuned from resonance by an amount Aco, the effective lifetime on the excited-state is i 1/Aco (adapted from [15]).

Wlrile tire Bms fonnula can be used to locate tire spectral position of tire excitonic state, tliere is no equivalent a priori description of the spectral widtli of tliis state. These bandwidtlis have been attributed to a combination of effects, including inlromogeneous broadening arising from size dispersion, optical dephasing from exciton-surface and exciton-phonon scattering, and fast lifetimes resulting from surface localization 1167, 168, 170, 1711. Due to tire complex nature of tliese line shapes, tliere have been few quantitative calculations of absorjDtion spectra. This situation is in contrast witli tliat of metal nanoparticles, where a more quantitative level of prediction is possible. 

Figure 1 Non-local layer dependent conductivity for majority electrons for parallel alignment of the cobalt moments. The scattering rate is assumed to be high so that the electron lifetime is relatively short (4.8X10 sec).

Since fatigue cracks often start at a random surface imperfection, considerable scatter occurs in fatigue data, increasing with the increasing lifetime wherever crack initiation occupies most of the fatigue life of a specimen. When a line of the best fit is drawn from the available data points on an S-N curve, this represents the mean life expected at any given stress level or the stress that would cause, say, 50% of the product failures in a given number of cycles. 

The presence of isotopic impurities causes clear effects in the vibrational spectra. Almost all modes studied so far show frequency shifts on S/ S substitution [81, 107]. The average shift of the internal modes is ca. 0.6 cm , and of the external modes it is 0.1-0.3 cm (Tables 3, 4 and 5). Furthermore, the isotopomers which are statistically distributed in crystals of natural composition can act as additional scattering centers for the phonon propagation. Therefore, in such crystals the lifetime of the phonons is shortened in comparison with isotopically pure crystals and, as a conse-... 

In order to compute the lifetime of a phonon of energy E, one averages the Golden Rule scattering rate (7ig A /pCj )tanh(p /2) with respect to n(e, A), subject to the resonance condition E = y/EA + A [8, 11, 93]. This yields two contributions to the decay rate ... 

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