180° pulse coupling

Figure 6.5 Dynamics of a classical electric dipole induced and driven on resonance by a sequence of two phase-locked ultrashort laser pulses, The driving laser field is shown as gray solid lines in all frames, In addition, the top frames show the induced dipole oscillation as a black dashed line. The instantaneous interaction energy V(t) of the induced dipole in the external driving field is shown in the bottom frames as a black dotted line. Bold black lines display the time average of the interaction energy In Figure 6,5a, the phase relation between both pulses is designed such that the second pulse couples in antiphase to...

Figure 4. Level scheme of a lambda-type double-resonance eperiment. The pump laser pulse couples the initial level 1 to a single rovibronic intermediate level 2 in the electronically excited Si state. The intermediate level 2 is coupled by the dump laser pulse to the vibra-tionally excited level 3 in the electronic ground state So- Ionization from level 2 is possible by absorption of an additional photon from the intense dump laser pulse. The coupling of the final level 3 to a single dark state (level 3a) is indicated and discussed in the text.

In resonant infrared multidimensional spectroscopies the excitation pulses couple directly to the transition dipoles. The lowest order possible technique in noncentrosymmetrical media involves three-pulses, and is, in general, three dimensional (Fig. 1A). Simulating the signal requires calculation of the third-order response function. In a small molecule this can be done by applying the sum-over-states expressions (see Appendix A), taking into account all possible Liouville space pathways described by the Feynman diagrams shown in Fig. IB. The third-order response of coupled anharmonic vibrations depends on the complete set of one- and two-exciton states coupled to thermal bath (18), and the sum-over-states approach rapidly becomes computationally more expensive as the molecule size is increased. 

Detection and identification of chemical warfare simulants based on multidimensional phase shaped femtosecond laser pulses coupled to mass spectrometry (MS) is demonstrated. The presented approach is based on binary phase shaping (BPS) and aims to improve the accuracy and precision required for security applications. It is based on multiphoton intrapulse interference of femtosecond laser pulses. Spectra retrieved by applying n-differently shaped pulses represent n-dimensions of the analysis. We present a multidimensional technique for detection and identification of analogues to chemical agents and mixtures in real-time. Experimental results for dimethyl phosphate, pyridine, and three isomers of nitrotoluene are presented. 

Mirollo, R. E., and Strogatz, S. H. (1990) Synchronization of pulse-coupled biological... 

Aberg, K.M. and Jacobsson, S.P. (2001) Preprocessing of three-way data by pulse-coupled neural networks - an imaging approach. Che-mom. Intdl. Lab. Syst., 57, 25-36. 

R. Mirollo and S. Strogatz. Synchronization of pulse-coupled biological oscillators. SIAM J. Appl. Math., 50 1645-1662, 1990. 

A magstim super rapid stimulator (The Magstim Company New York, NY), which produces a biphasic pulse, coupled with either the figure-8 coil or the H-coil, was used. Prehminary studies showed the H-coil to have a loudness when activated of 122 dB, similar to other cods used in our laboratory. As a standard laboratory practice, subjects were fitted with foam ear plugs to attenuate the sound. 

Synchronization and Activity Patterns in Pulse-Coupled Neural Nets with Delays and Noise By H. Haken... 

Halogen Compounds. Weakly hydrogen-bound van der Waals complexes of PH3 with hydrogen halides were generated from the diluted gases. The reactions were carried out either by pulsed-nozzle supersonic expansion with pulse-coupled microwave spectroscopic detection (MW) or by isolation in matrices at low temperature with identification by IR spectroscopy (IR). Experimentally observed complexes are H3P---HF (MW [2], IR [8]), H3P---HCI (MW [4], IR [3, 5]), and H3P---HBr (MW [6], see also [4]). 

We first consider the ARPA scenario illustrated in Figure 8.1a in which we address PA of an initial wavepacket composed of near-threshold i-wave scattering states of two Rb atoms colliding on theX E+ potential. (The numerical parameters are given in Section 8.5 and Ref. [17].) The pump pulse couples this initial state to an excited intermediate bound state belonging to the A EjJ" and n spin-orbit-coupled states, 11 > = AiE+-fe n (i) = 133,/= 1) ( 1 = 0.042848au). The anti-Stokes dump pulse couples this intermediate state to the target state 0> = = 4,/ = 0) E =... 

The presence of additional bound states not included in the simplified theory does not destroy the effectiveness of the detection scheme. Such robustness was quite unexpected in the KRb simulations because the central wavelength of one of the pump pulses is just 1.2 nm away from an exact resonance with an undesired transition between the states 1) and 3) (see Figure 8.1c). We attribute the high robusmess of the scheme to the counterintuitive structure of the pulse sequence by the time the pump pulse couples the states 3> and 1), state 1) is already mixed with the target state 0) in such a way that the population of 11> remains negligible at all times. 

FIGURE 16.3 The scheme for Raman spectroscopy of Sr2 ground-state vibrational spacings. A two-color photoassociation pulse prepares molecules in the v = Umax — 2 vibrational state (labeled in the figure as u = —3). Subsequently, a Raman pulse couples the v = —3 and v = 21 states via the u 40 level of the excited 0 state. (From Zelevinsky, T. et al., Phys. Rev. Lett., 100, 043201, 2008 arXiv 0708.1806, 2007. With permission.)... 

Simulations of that kind result in a wide variety of A-scans and wavefront snapshots. The first screening of this material reveals, that the simulations in which the transducer is coupling partly to the V-butt weld and partly to the steel exhibit quite a number of pulses in the A-scans because the coupling at the interface of the weld results — due to the anisotropic behavior of the weld — in a complicated splitting of the transmitted wavefront. The different parts of the splitted wavefront are reflected and diffracted by the backwall, the interface, and — if present — by the notch and, therefore, many small signals are received by the transducer, which can only be separated and interpreted with great difficultie.s. 

Only the simulations in which the transducer is coupling either to the V-butt weld or to the surrounding steel can be analyzed in a simple and intuitive way, which means that the different pulses in the A-scan signals can be related uniquely to the reflection or diffraction of the wavefront at the weld, the backwall, and/or the notch. 

Due to the pulsed radiation output of the LINAC the detectors and the detector electronics have to handle very high counting rates in very short periods. Therefore the detectors have to work in a mode, where the detector output is integrated for one or several beam pulses. For that purpose the crystals are coupled to photo- diodes. Their currents are read out and analysed by the electronic board, which has been developed for this special application. 

The Champ-Sons model is a most effieient tool allowing quantitative predictions of the field radiated by arbitrary transducers and possibly complex interfaces. It allows one to easily define the complete set of transducer characteristics (shape of the piezoelectric element, planar or focused lens, contact or immersion, single or multi-element), the excitation pulse (possibly an experimentally measured signal), to define the characteristics of the testing configuration (geometry of the piece, transducer position relatively to the piece, characteristics of both the coupling medium and the piece), and finally to define the calculation to run (field-points position, acoustical quantity considered). 

Time-resolved spectroscopy has become an important field from x-rays to the far-IR. Both IR and Raman spectroscopies have been adapted to time-resolved studies. There have been a large number of studies using time-resolved Raman [39], time-resolved resonance Raman [7] and higher order two-dimensional Raman spectroscopy (which can provide coupling infonuation analogous to two-dimensional NMR studies) [40]. Time-resolved IR has probed neutrals and ions in solution [41, 42], gas phase kmetics [42] and vibrational dynamics of molecules chemisorbed and physisorbed to surfaces [44]- Since vibrational frequencies are very sensitive to the chemical enviromnent, pump-probe studies with IR probe pulses allow stmctiiral changes to... 

---