Energy relaxation times

If the. /-diffusion model is valid but only the energy relaxation time is known then Eq. (1.57) may be used to find the other ... 

Experimental verification of the universal wing shape (4.90) is not only an important way of checking the dominant role of spectral exchange but also an additional spectroscopic way to measure energy relaxation time even before collapse (in rare gases). Unfortunately it has not been done yet due to lack of accuracy far beyond the spectral edge. 

First, it is assumed that the EEDF is spatially uniform and temporally constant, which is allowed if the energy relaxation time of the EEDF is much shorter than the RF-cycle duration, and if the relaxation length is much smaller than the typical gradient scale length. This assumption implies a spatially and temporally constant electric field. It reduces the Boltzmann equation to a problem exclusively in the velocity space. 

The finite decoherence time is due to some inelastic scattering mechanism inside the system, but typically this time is shorter than the energy relaxation time re, and the distribution function of electrons inside the system can be nonequilibrium (if the finite voltage is applied), this transport regime is well known in semiconductor superlattices and quantum-cascade structures. 

The other important point is that the distribution function fn a) in the charge state n) is not assumed to be equilibrium, as previously (this condition is not specific to quantum dots with discrete energy levels, the distribution function in metallic islands can also be nonequilibrium. However, in the parameter range, typical for classical Coulomb blockade, the tunneling time is much smaller than the energy relaxation time, and quasiparticle nonequilibrium effects are usually neglected). 

Laenen R, Rauscher C. Time-resolved infrared spectroscopy of ethanol monomers in liquid solution molecular reorientation and energy relaxation times. Chem Phys Lett 1997 274 63-70. 

Interactions of pump and probe pulses with a material absorption are usually described by density matrix equations for a distribution of two-level or three-level systems. The formulation of these equations can be found in textbooks and other reviews [8,9]. We try here simply to describe in physical terms the ways in which the different parameters of the equations manifest themselves experimentally. The simplest theoretical case is the two-level system, in which is the dephasing time of the coherently induced electronic polarization and Tj is the energy relaxation time. We begin our discussion by simplifying even further and assuming that Tj is very short compared to the optical pulse durations. Then, the coherent polarization follows the optical... 

Short-range forces will give a collisional contribution that may be calculated in a similar way to energy relaxation times. 

Comparison of Available Nonradiative Vibrational Energy Relaxation Times in Liquid and Solid Near Melting Point, Showing Essential Continuity of Process across Phase Transition... 

In many physical systems the situation becomes simpler due to the inherent stochastic nature of the driving field itself. To see the possible significance of this effect, consider a conventional COj-laser pulse with 10-ns duration and a bandwidth of 1 cm incident on a diatomic molecule characterized by an environment-induced energy relaxation time of 100 ns. The laster pulse is obviously not uncertainty limited, and its width is associated with the random fluctuations in its phase and/or amplitude. For simplicity we consider random phase fluctuations, whence the external field is... 

Figure 1.37. Energy relaxation time as a function of temperature for (H20)2o- (a) The starting distribution corresponds to a very high temperature 1 O K for each point, (b) The equilibrium distribution at double the temperature of interest is used as the starting point in every case. The three data sets correspond to samples, I, II, and III described in the text.

Note, however, that electrical conductivity is related to the momentum relaxation time, whereas the thermal conductivity is related to the energy relaxation time. They are usually close at room temperature or at very low temperatures. 

As expected, slower heme cooling was observed for the modified heme relative to native heme (see Table 9.1). For Mb in pure aqueous solution, the kinetic energy relaxation time constants were observed to be 5.1 0.2 and 8.3 0.3 ps for the native heme and the modified heme, respectively. A small change was observed from our previons simnlation resnlts of 5.9 0.2 ps for native heme [57] and 8.8 0.3 ps for modified heme, [62] dne to the nse of the refined penta-coordinate heme parameters for the heme following photolysis [66], The solvent-dependent heme cooling rates were observed for both native and modified Mb (see Table 9.1). 

Excess Kinetic Energy Relaxation Time Constants in "Heme Cooling" Eollowing Ligand Photolysis of CO in Myoglobin Simulated Using Classical Molecular Dynamics at 300 K... 

J. Chesnoy and J. J. Weis, J, Chem. Phys., 84, 5378 (1986). Density Dependence of the Dephasing and Energy Relaxation Times by Computer Simulations. 

The d3mamical behavior of the cyanide ion (CN ) has been well studied experimentally [138-140]. Atomistic simulations have shown to give energy relaxation times in good agreement with experiments [49, 141]. It has been found that vibrational energy relaxation is particularly sensitive to the level at which the... 

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