Phase jumping

The Impedance Z can Increase to very high values. If this happens, the oscillator prefers to oscillate In resonance with an anharmonic frequency. Sometimes this condition Is met for only a short time and the oscillator oscillation jumps back and forth between a basic and an anharmonic oscillation or It remains as an anharmonic oscillation. This phenomenon Is well known as "mode hopping". In addition to the noise of the rate signal created, this may also lead to Incorrect termination of a coating because of the phase jump. It Is Important here that, nevertheless, the controller frequently continues to work under these conditions. Whether this has occurred can only be ascertained by noting that the coating thickness Is... 

Switching electronic population to different final states with high efficiency via SPODS is a fundamental resonant strong-field effect as the only requirement is the use of intense ultrashort laser pulses exhibiting temporally varying optical phases, such as phase jumps [67, 68, 70, 71] or chirps [44, 72]. Only recently, these concepts were transferred to molecules, where the coupled electron-nuclear dynamics have to be considered in addition [73,74]. 

In the following, we will discuss two basic - and in a sense complementary [44] - physical mechanisms to exert efficient control on the strong-field-induced coherent electron dynamics. In the first scenario, SPODS is implemented by a sequence of ultrashort laser pulses (discrete temporal phase jumps), whereas the second scenario utilizes a single chirped pulse (continuous phase variations) to exert control on the dressed state populations. Both mechanisms have distinct properties with respect to multistate excitations such as those discussed in Section 6.3.3. 

Figure 6.10 Ultrafast efficient switching in the five-state system via SPODS based on multipulse sequences from sinusoidal phase modulation (PL). The shaped laser pulse shown in (a) results from complete forward design of the control field. Frame (b) shows die induced bare state population dynamics. After preparation of the resonant subsystem in a state of maximum electronic coherence by the pre-pulse, the optical phase jump of = —7r/2 shifts die main pulse in-phase with the induced charge oscillation. Therefore, the interaction energy is minimized, resulting in the selective population of the lower dressed state /), as seen in the dressed state population dynamics in (d) around t = —50 fs. Due to the efficient energy splitting of the dressed states, induced in the resonant subsystem by the main pulse, the lower dressed state is shifted into resonance widi die lower target state 3) (see frame (c) around t = 0). As a result, 100% of the population is transferred nonadiabatically to this particular target state, which is selectively populated by the end of the pulse.

The third line describes oscillation of a wave packet in an anharmonic potential (phase term omitted). Eq. (1) would be valid also in the presence of an intermediate resonance. In Eq. (2), the Apl dependence is only in the Plon terms. The fundamental arises from the sin terms (hence from dPion/dx) and the overtone from the sin2 terms. A phase jump of the fundamental is expected at a Tpr where dPlnn/dx and hence dPloir/dIE change sign. From these derivatives (proportional to the fundamental amplitude in Fig. 3) we can infer that Ploa has a maximum at 680 nm and a minimum near 405 nm. The maximum could reflect either an intermediate resonance or a two-photon resonance with an autoionizing state. The minimum is likely to announce a further rise of PIon at shorter Apr due to the lower order of ionization. 

A solute that exhibits some affinity toward the stationary phase jumps from one phase to another. It is retained for a while in the stationary phase, with the consequence that its average speed of travel is less than that of the unretained solute. Retention time is tr > t . We thus can write /, = / il + k), where k = (tr — t0)/t0. k is the retention factor (formerly called capacity factor). The retention factor is a measure of the time the sample component resides in the stationary phase relative to the time it resides in the mobile phase. 

For spins which did diffuse from their original position (or more accurately who changed their x-coordinate value) during the time change, the phase jump their magnetisation vector acquired during the first pulse is not compensated by the phase jump during the second pulse and their contribution to the echo intensity is decreased. 

FAM-II pulses were initially shown to enhance the 3QC <- SQC conversion process in a spin-5/2 system.Later they were also used for excitation purposes by transferring 3QC <->5QC coherences in SQM AS experiments. Figure 12c shows a schematic of a FAM-II sequence, which consists of a train of pulses of progressively decreasing duration with alternating phases of 0° and 180° separated by an interpulse delay. The interpulse delay is normally kept to the minimum value required for stabilization of the phase jumps between the pulses, say 0.2-0.4 p,s. Such a FAM-II sequence is denoted as F (r), where n again corresponds to the number of pulses (it can be odd or even in contrast to the F (t) case) and F is a vector containing the durations of the pulses and interpulse delays. 

Grigorenko AN, Nikitin P, Kabashin AV (1999) Phase jumps and interferometric surface plasmon resonance imaging. Appl Phys Lett 75 3917-3919... 

Figure 12. Particle transfer in a double-well potential. The initial wavepacket is localized in the potential well at positive distances (panel (a)). The LCT field induces a vibrational motion and drives the packet over the barrier, as can be taken from the coordinate expectation value displayed in panel (b). A phase jump is introduced in the field (panel (c)) at the time the barrier is passed, and afterwards a trapping in the second potential well takes place.

Let us first regard the field inducing the (B) <— (C) <— (A) process. The constructed field exhibits phase jumps at those times when the heating and... 

When the footing has an optical origin, it is related to a phase jump of the reflected light at the interface between the BARC and the resist. The magnitude of the phase angle change depends on the film s optical constants and its thickness. The phase jump can result in a standing wave at the resist-BARC interface. A resist... 

The phase near the Ge-nucleus of the waves scattered by the Cl-atoms in our example will dependupontheir wave-length A, the distance and the phase jump 8 taking place in the... 

Because no voltage drops across an open circuit, no energy is dissipated by the MUT. Therefore, all energy is reflected but with the opposite polarity Vref = Vinc- The superposition of the incident and the reflected voltage is zero. In case of sinusoidal voltage, the reflected wave shows a phase jump of 180° at the MUT. 

V sinO < y/k, the molecule after the collision is still in resonance with the standing light wave inside the laser resonator. Such soft collisions with deflection angles 0 < therefore do not appreciably change the absorption probability of a molecule. Because of their statistical phase jumps (Vol. 1, Sect. 3.3) they do, however, contribute to the linewidth. The line profile of the Lamb dip broadened by soft collisions remains Lorentzian. 

It is also possible to observe the Ramsey resonances at z = 2L without the third laser beam. If two standing waves at z = 0 and z = L resonantly interact with the molecules, we have a situation similar to that for photon echoes. The molecules that are coherently excited during the transit time t through the first field suffer a phase jump at r = T in the second zone, because of their nonlinear interaction with the second laser beam, which reverses the time development of the phases of the oscillating dipoles. At r = 2T the dipoles are again in phase and emit coherent radiation with increased intensity for co = a>ik (photon echo) [1258,1263]. 

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