Strong field experiment

It is possible to work in a basis set in which the nuclear spins are coupled, both to each other and also to./ the analysis of the spectrum by Trischka [50] was accomplished using a coupled basis set for weak field experiments, and a fully decoupled basis for the strong field experiments. We will evaluate the matrix elements in both bases. 

Finally, there is one other experiment that we know of that found a resonant signature in the strong field excitation of a molecule. In this experiment, the symmetric dissociation channel of 0 + was monitored in a high resolution coincidence ion spectrometer [41]. From the KER of the fragments, excitation to the B3iTg state was identified, among other states. However, this particular... 

Lastly, we mention one more excitation mechanism that has been observed in molecules. It is well-established that following strong field ionization in atoms and molecules, under certain conditions, the ionized electron can be driven back to the ion core where it can recombine to produce high-harmonic radiation, induce further ionization, or experience inelastic scattering. However, there is also the possibility of collisional excitation. Such excitation was observed in [43] in N2 and O2. In both molecules, one electron is tunnel ionized by the strong laser field. When the electron rescatters with the ion core, it can collisionally ionize and excite the molecular ion, creating either N + or Ol+ in an excited state. When the double ion dissociates, its initial state can... 

Important aspects of the interaction of strong laser fields with molecules can be missed in standard TOF experiments, most notably the population of electronically excited states. However, by studying vibrational excitation, the frequency and dephasing of the vibrational motion can be used to identify the electronic state undergoing the vibrational motion. In some cases, this turns out to be a ground state, and in others, an excited state. Once we have identified an excited state, we are left with the question of how and why the state was populated by the strong field. In one example above (the Ij A state discussed in Sect. 1.3.3), the excited state is formed by the removal of an inner orbital electron, in this case a iru electron. This correlates with the measured angular dependence for the ionization to this state. 

In Section 6.3.2, we presented experimental data from strong-field excitation and ionization of K atoms with shaped femtosecond laser pulses. Here we give a description of the apparatus and strategy used in the experiments presented in this contribution. Figure 6.12 gives an overview over the complete experimental two-color setup. For the experiments on strong-field control of K atoms (cf Sections 6.3.2.2, 6.3.2.3, and 6.5) only the one-color beamline was used. An... 

In the experiment, we measured photoelectron spectra from strong-field excitation and simultaneous two-photon ionization of K atoms with BWL (unmodulated) IR pump pulses, as a function of the pulse energy W [68]. The results for energies ranging from W = 0.35 to 2 pj are shown in logarithmic representation in Figure 6.13. All photoelectron spectra exhibit the AT doublet as a signature of the... 

These experiments will show that Cs adions do exist and that they produce strong fields which produce large forces on the electrons near the surface these fields also modify the behavior of other adions or adatoms over distances of 20 to 40 X 10 cm. Because of these long-range forces, the adsorption properties of Cs are greatly dependent on the concentration of adsorbed Cs. In other cases in which the tendency to form ions is much smaller or in which the ionic radius is smaller, the electrical fields are smaller and die off more rapidly with distance from an adion. For... 

The use of strong fields to drive the dynamics leads to somehow similar effects than those of ultrafast pulses. If the Rabi frequency or energy of the interaction is much larger than the energy spacing between adjacent vibrational states, a wave packet is formed during the laser action. The same laser can prepare and control the dynamics of the wave packet [2]. Both short time widths and large amplitudes can concur in the experiment. However, the precise manipulation of dynamic observables usually becomes more difficult as the duration of the pulses decreases. 

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