Laser dressed

Figure 2.7 Potential energy curves of Hj" in a 750 nm laser-dressed diabatic representation (black solid lines). Are also indicated the lower adiabatic curves resulting from the diagonalization of the radiative interaction for two intensities (/ = 3 x plO W/cm reached at mid-pulse time, in red dashed line and / = 10 W/cm in doted red line). Ej, E, and 9 represent the kinetic energies issued from v+ = 7, 8, and 9 for the typical XUV-IR delays [about 100 fs (a) and Ofs (b)].

Thermal dressing can be categorized to laser dressing, electro-discharge dressing (EDD),... 

Chen M, Sun F, Liu G, Jian X, Li X (2003) Theoretical and experimental research on generation mechanism of grinding wheel topography by laser dressing and 3D laser scanning. Key Eng Mater 233-236 497-502... 

Waldemeyer, M., 2013. Hussein Chalayan Readings Collection (S/S 2008). Moritz Waldemeyer Innovative and Creative Solutions. Available at http //www.waldemeyer. com/hussein-chalayan-readings-laser-dresses (accessed 25.05.13). 

In order to treat the reaction in the laser field, we introduce an idea of "laser dressed" states [7]. Photoabsorption and photoemission processes are then modeled as the nonadiabatic transitions between the dressed ground and excited states. Under the assumptions of (1) two-state model, (2) single-photon excitation, and (3) rotating wave approximation, the laser dressed adiabatic PESs are given for two diabatic PESs W- and and the laser frequency as [7],... 

Fig. 2 shows the diabetic laser dressed PESs between the lA and 3A states for the laser wavelength x 700 nm. The PESs are fitted to Murrell and Sorbie type analytical functions [9]. In... 

Figure 2. Laser-dressed PES for K + NaCl (x = 700 nm). Contours are drawn for each 0.2 eV up to 1.2 eV above the ground state reactant. R1 and R2 denote the K-Cl and Na-Cl bond lengths, respectively and e is the KClNa angle.

Dalibard J and Cohen-Tannoudji C 1985 Dressed-atom approach to atomic motion in laser light the dipole force revisited J.Opt.Soc.Am. B 21707-20... 

Once the mechanisms of dynamic processes are understood, it becomes possible to think about controlling them so that we can make desirable processes to occur more efficiently. Especially when we use a laser field, nonadiabatic transitions are induced among the so-called dressed states and we can control the transitions among them by appropriately designing the laser parameters [33 1]. The dressed states mean molecular potential energy curves shifted up or down by the amount of photon energy. Even the ordinary type of photoexcitation can be... 

Fig. 1.2. Potential energy curves of H2 and Hj showing ionization and dressed states in a laser field. The dressed curves lead to bond softening and a distortion of the potential curve of the ground state of the ion, as will be discussed in Sect. 1.2.3...

The new diagonal elements are the eigenenergies e (t) and e (t) of the lower and upper dressed state /) and u), respectively. In intense laser fields, the dressed states split up according to... 

For resonant excitation, 5 = 0, the splitting is determined only by the amplitude of the Rabi frequency, which is conveniently adjusted via the laser field amplitude. Finally, we obtain the population dynamics d t) = dJ(t)Y in the dressed state picture from the bare state amplitudes by the transformation d t) = V t)c t). 

In order to relate the dressed state population dynamics to the more intuitive semiclassical picture of a laser-driven charge oscillation, we analyze the induced dipole moment n) t) and the interaction energy V)(0 of the dipole in the external field. To this end, we insert the solution of the TDSE (6.27) into the expansion of the wavefunction Eq. (6.24) and determine the time evolution of the charge density distribution p r, t) = -e r, f)P in space. Erom the density we calculate the expectation value of the dipole operator... 

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.

Note that SPODS is nearly always operative in resonant strong-held excitation using modulated ultrashort laser pulses, the only exception being so-called real laser pulses [72, 77] (i.e., electric helds with only one quadrature in the complex plane) that are usually hard to achieve in ultrafast laser technology. This is why many different pulse shapes can lead to comparable dressed state energy shifts and... 

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