Multiple excitations

A Campbell diagram is frequently used to determine the effect of multiple excitation frequencies in high-speed steam turbines. Figure 7-11 shows a Campbell diagram for a condensing steam turbine. If this partic uiar turbine operates at a speed of 8,750 rpm, the turbine blades would not be excited. But, if the turbine speed is reduced to 7,500 rpm, the turbine blades would be excited at four times running speed. If the turbine were operated at 10,000 rpm, a three-times running speed excitation would be encountered. What this means is that any vibration in the... 

Lee, S.A. Jiao, C.Q. Huang, Y. Preiser, B.S. Multiple Excitation Collisional Activation in FTMS. Rapid Commun. Mass Spectrom. 1993, 7, 819-821. 

TOPHAT-shaped 90° pulses are used in other cases as the best compromise with respect to the excitation profile, the phase homogeneity and length. Depending on the type of the detected spin-spin interaction - being either scalar or dipolar coupling - each selected spin is initially perturbed only once (ID TOCSY, ID INADEQUATE, ID C/H COSY, 2D TOCSY-COSY and 2D HMBC), or for several times (ID NOE). With each of the selected spins initially perturbed only once the inherently smaller transient NOEs would be detected in the latter case, whereas with the multiple excitation of a selected spin within the NOE build-up period the stronger steady-state NOEs are more or less approximated. 

Secondly, the emission of a particular complex species is characteristic of that species and can be used to identify the species present. Particularly is this so if excited state lifetimes are measured, as these vary dramatically depending on the number of OH groups coordinated to the Eu3+ or Tb3+ ion. This is because multiple excitation of the OH stretching mode provides an alternative deexcitation route. Measurement of lifetimes thus can be used to determine the number of coordinated water molecules.218... 

Instead of realizing the Shah detector function using the multiple slits, multiple excitation points were created. This was achieved by monolithically integrating multiple planar waveguide beam splitters on a fluidic channel. In this way, 128 excitation points were created on the fluid channel for multipoint fluorescent detection [413]. 

An STM manipulation mechanism related to the adsorption and desorption processes of single atoms and molecules is known as vertical manipulation (Fig. 10). This process involves transfer of single atoms or molecules between the tip and substrate and vice versa (Fig. 10(a)). An atomic switch realized by the repeated transfer of a Xe atom between the STM tip and a Ni(110) substrate is the first example of vertical manipulation [22]. The atom/molecule transfer process can be realized by using an electric field between the tip and sample, or by multiple excitations with inelastic tunneling electrons, or by making mechanical contact between the tip and atom/molecule. This transfer mechanism can be modeled by using a double potential well as shown in Fig. 10(b). At an imaging distance, approximately 6 A between tip and surface, the atom/molecule has two possible... 

Fig. 13. Schematic illustration of the IET dissociation process, (a) Inelastic electrons are injected into the molecule through the adsorbate-induced resonance state, (b) The energy required for a dissociation can be supplied by single- or multiple-excitation processes.

This approach allows for a complete calculation of transport in the presence of vibrations and interacting with them. In this way, the effect of temperature (through phonon population, i.e. degree of excitation of the vibrations) and multiple excitations is taken into account. The inclusion of multiple electronic channels permits them to go beyond the above resonance models the molecule can have several orbitals contributing to the conductance and to the coupling with its vibrations [28]. 

Optical excitation of metals with intense femtosecond laser pulses can create extreme non-equilibrium conditions in the solid where the electronic system reaches several thousand degrees Kelvin on a sub-picosecond timescale, while the lattice (phonon) bath, stays fairly cold. As illustrated in Figure 3.22, photoexcited hot electrons may transiently attach to unoccupied adsorbate levels and this change in the electronic structure may induce vibrational motions of the adsorbate-substrate bond. For high excitation densities with femtosecond pulses, multiple excitation/deexcitation cycles can occur and may eventually lead to desorption of adsorbate molecules or reactions with co-adsorbed species. After 1-2 ps, the hot electron... 

Aberg, T. Shake theory of multiple excitation processes. In Photoionization and other probes of many-electron interactions. Wuilleumier, F. (ed.), pp. 49-59. NATO Advanced Study Institute Series. New York Plenum Press 1976... 

This argument motivates the idea that the way to control photodissociation is to eii e more than one initial state, or in greater generality, to use multiple excitation pathways. In this chapter we demonstrate that such a strategy allows us to actively /rtipijence and control which photodissociation product is formed. These ideas, which firbduce the notion of coherent control, will be later shown to hold true for any lical process, not just for photodissociation. 

Note, throughout these experiments it has been necessary to eliminate multiple excitation of single antennae which result in annihilation and rapid initial decay of the bleach. This is not observed if the magnitude of the initial 690nm signal is reduced to less than 0.1 OD. 

Fixed spatial phase in the grating pattern also facilitates experiments with multiple excitation pulses (20). A second, delayed pulse incident on the diffractive optic is split in the same manner as the first and results in a second excitation pattern with the same peak and null positions. Thus, multiple excitation gratings, delayed temporally and shifted spatially if desired, can be used for excitation of phonon-polaritons whose coherent superposition is well controlled. A preliminary experiment of this type has been reported (21). 

It is clear, however, from the discussion involving Eqs. (7)—(9) and from the sudden approximation sum rule that the spectrum associated with the photoionization of a core electron should not, in fact, necessarily consist only of a single line some data observed for RbCl and RbF (40) are shown in Fig. 16. The narrow peaks are the Rb 4s24 6(1S) - -4s14 >6(2S) excitation and the broad peaks, approximately equal in intensity, arise from multiple electron excitation , that is, the production of final states such as 4s24 4 s(2S), where n > 5. Even though the photoemission event is just a one-electron dipole process, multiple excitation can occur because the wavefunction of the instantaneous intermediate state of the (TV—1)-electron ion [Eq. (7)] has overlap with wavefunctions of such multiply excited states that is, i has components which are eigenfunctions, n(N—1), of multiply... 

The Eq. (4-9) is an eigen equation and gives multiple excited states by single diagonalization. The different SAC-CI solutions are therefore orthogonal to each other. 

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