Golden rule of time-dependent

From the definition of 6k it should be noted that Bk and k are Hermitian conjugates. According to the Golden Rule of time-dependent perturbation theory the probability per unit time, Wt f k, co), that the field (k, to) induces a transition in the system from the initial state f> to the final state / ) is given by... 

Much more is becoming known about the rates of the physical processes in competition with proton exchange reactions in excited states. (For an excellent review see Henry and Siebrand, 1973.) The factors which determine the rate constants (k) for internal conversion and intersystem crossing are neatly summarized in the Golden Rule of time-dependent perturbation theory ... 

Several quantum mechanical calculations have been made for electron transfer processes between metals and atoms or ions " in gaseous medium. In all the cases, the considerations concern the transition of electrons from a metal state to a bound atomic state or to a free continuum state or vice versa. The calculations of transition probabilities in the cited works have been based on Fermi s golden rule of time-dependent perturbation theory. However, it was pointed out by Gadzuk that the use of the golden rule usually presents a difficult problem if an estimate of the transition probability is desired, because it requires evaluation of a matrix element one must specify initial and final state (wave functions) and an interaction. This is not as straightforward as it seems. In a transition, e.g., between an atomic and a conduction band metal state, the initial and final states are eigenfunctions of different Hamiltonians. It seems meaningless to evaluate matrix elements, if the initial and final states are solutions of different Hamiltonians. 

Thus, to have a proper estimate of photocurrent from expression (75), it is desirable to calculate the transition probability, T E,hv)y using the time-dependent perturbation theory. The general expression of T E, hv) in terms of Fermi s golden rule of time-dependent perturbation theory... 

The Golden Rule of time-dependent perturbation theory now yields, for the probability of scattering per unit time from state i// k) to y/ k -I- q),... 

The asymmetric dependence of the activation energy on the driving force (energy-gap law) of ET reactions can be reproduced using the golden rule of time-dependent perturbation theory. The golden rule allows for the calculation of the transition rate from an initial to a final electronic state subject to a weak perturbation applied for a short period of time. The ET rate constant was first expressed in terms of the golden rule in the 1970 s ... 

Fermi called eq. (15.36) the Golden Rule of time-dependent perturbation theory because of its prevalence in radiationless transitions. Sometimes it is referred to as Fermi s Golden Rule. 

Many experimental techniques now provide details of dynamical events on short timescales. Time-dependent theory, such as END, offer the capabilities to obtain information about the details of the transition from initial-to-final states in reactive processes. The assumptions of time-dependent perturbation theory coupled with Fermi s Golden Rule, namely, that there are well-defined (unperturbed) initial and final states and that these are occupied for times, which are long compared to the transition time, no longer necessarily apply. Therefore, truly dynamical methods become very appealing and the results from such theoretical methods can be shown as movies or time lapse photography. 

For a quantitative treatment of establishing connections between vibronic coupling and vibrational progressions in electronic spectra, band profiles from vibronic wavefunctions must be calculated using common procedures of time-dependent perturbation theory and Fermi s golden rule [57], For emission, e.g., the transition rate which is the transition probability per unit time summed over... 

According to Fermi s golden rule [40, 42], the integral intensity A of the absorption band of the normal mode is proportional to the probability per unit time of a transition between an initial state i and a final state j. Within the framework of the first (dipole) approximation of time-dependent perturbation quantum theory [46, 65], this probability is proportional to the square of the matrix element of the Hamiltonian H = —E p, where E is the electric field vector and p is the electric dipole moment, resulting in the absorption... 

The probability for a transition to occur between two states per unit time is determined by Fermi s golden rule and depends on the operator of interaction between the subsystem concerned and a thermostat. As orientational states are characterized by a low-energy spectrum, they will be substantially influenced by the... 

The purpose of this work is to study the electronic predissociation from the bound states of the excited A and B adiabatic electronic states, using a time dependent Golden rule (TDGR) method, as previously used to study vibrational pre-dissociation[32, 33] as well as electronic predissociation[34, 35], The only difference with previous treatments[34, 35] is the use of an adiabatic representation, what requires the calculation of non-adiabatic couplings. The method used is described in section II, while the corresponding results are discussed in section III. Finally, some conclusions are extracted in section IV. 

Recently, the electron-transfer kinetics in the DSSC, shown as a schematic diagram in Fig. 10, have been under intensive investigation. Time-resolved laser spectroscopy measurements are used to study one of the most important primary processes—electron injection from dye photosensitizers into the conduction band of semiconductors [30-47]. The electron-transfer rate from the dye photosensitizer into the semiconductor depends on the configuration of the adsorbed dye photosensitizers on the semiconductor surface and the energy gap between the LUMO level of the dye photosensitizers and the conduction-band level of the semiconductor. For example, the rate constant for electron injection, kini, is given by Fermi s golden rule expression ... 

Not only is the master equation more convenient for mathematical operations than the original Chapman-Kolmogorov equation, it also has a more direct physical interpretation. The quantities W(y y ) At or Wnn> At are the probabilities for a transition during a short time At. They can therefore be computed, for a given system, by means of any available approximation method that is valid for short times. The best known one is time-dependent perturbation theory, leading to Fermi s Golden Rule f)... 

In one quantum mechanical approach based on the diabatic approximation , the electron is assumed to be confined initially at one of the reactant sites and electron transfer is treated as a transition between the vibrational levels of the reactants to those of the products. The quantum mechanical treatment begins with the time dependent Schrodinger equation, Hip = -ihSiplSt, where the wavefunction tj/ is written as a sum of the initial (reactant) and final (product) states. In the limit that the Bom-Oppenheimer approximation for the separation of electronic and nuclear motion is valid, the time dependent Schrodinger equation eventually leads to the Golden Rule result in equation (25). 

Because of the time dependence of the vector potential A(rJ( t), the photon-atom interaction also depends on time. Hence, time-dependent perturbation theory has to be applied. The golden rule (so called by Fermi [Fer50], see also [Dir47, Sch55, LLi58]) for the transition rate w then yields for the change from an initial atomic state i> to a final atomic state f>... 

The conflicting serial/parallel models for IVR/VP are not readily distinguished until time resolved experiments can be performed on the systems of interest. Both models can relate the relative intensities of the emission features to the various model parameters, but the serial process seems more in line with a simple, conventional [Fermi s Golden Rule for IVR (Avouris et al. 1977 Beswick and Jortner 1981 Jortner et al. 1988 Lin 1980 Mukamel 1985 Mukamel and Jortner 1977) and RRKM theory for VP (Forst 1973 Gilbert and Smith 1990 Kelley and Bernstein 1986 Levine and Bernstein 1987 Pritchard 1984 Robinson and Holbrook 1972 Steinfeld et al. 1989)], few parameter approach. Time resolved measurements do distinguish the models because in a serial model the rises and decays of various vibronic states should be linked, whereas in a parallel one they are, in general, unrelated. Moreover, the time dependent studies allow one to determine how the rates of the IVR and VP processes vary with excitation energy, density of states, mode properties, and isotropic substitution. 

The V-B coupling Hamiltonian to first order in the three HOD dimensionless normal coordinates is Hv b = —2, c], l , where F, is the inter-molecular force due to the solvent exerted on the harmonic normal coordinate, evaluated at the equilibrium position of the latter. This force obviously depends on the relative separations of all molecules, and on their relative orientations. In the most rigorous quantum description of rotations, this term would depend on the excited molecule rotational eigenstates and of the solvent molecules. Instead rotation was treated classically, a reasonable approximation for water at room temperature. With this form for the coupling, the formal conversion of the Golden Rule formula into a rate expression follows along the lines developed by Oxtoby (2,53), with a slight variation to maintain the explicit time dependence of the vibrational coordinates (57),... 

The method proposed by Fermi (1934) for calculating the / decay of a nucleus is based on the time-dependent perturbation theory. The small value of the weak-interaction constant makes it possible to restrict oneself to the first order in perturbation theory and to use the so-called Fermi Golden Rule... 

The transition probability per unit time given by the time-dependent perturbation theory, that Fermi named Golden Rule in view of its prevalence in radiationless transitions, has the form... 

This expression is the exact form of Fermi s Golden Rule, familiar in time-dependent perturbation theory where F[, 0)) is approximated by o) (Merzbacher, 1970). p( ,) is the density of final states. 

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