Above Threshold Ionization ATI

When molecules are subjected to high-power laser radiation, ionization occurs, but of course so too does violent photodissociation. When a lot of electrons are removed, the remaining highly charged atoms cannot stay together a Coulomb explosion occurs. High-power dissociation processes are discussed in [9.242-9.246]. 

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The resulting phenomena of above-threshold dissociation (ATD) resemble those of above-threshold ionization (ATI) see Ref. 34. 

At larger radii, eight-photon, above-threshold ionization (ATI), and a small amount of nine-photon (two-photon ATI) are observed. These are labeled as 8hv and 9hv in Figure 8A. These signals are very weak and the intensity is distributed over many vibrational levels. Within the first abovethreshold ionization signal (corresponding to eight-photon ionization) one... 

Fig. 1. Schematic diagram showing above threshold ionization (ATI) and high harmonic generation (HHG)...

Projection onto scattering states provides additional information concerning the continuous spectrum, such as the understanding of above threshold ionization" (ATI) in the presence of a dc field [183] or of angular distributions of the emitted electron. 

We can clearly consider a laser to be strong when its intensity becomes comparable to (4.113). In this regime, perturbation theory is no longer applicable, and the theorist has to resort to non-perturbative methods. When approaching these high intensities, a wealth of non-linear phenomena appear, like multi-photon ionization, above threshold ionization (ATI), high harmonic generation, etc. 

The measured energy spectrum of the outgoing photo-electrons is called the above threshold ionization (ATI) spectrum [69]. As the electron can absorb more photons than necessary for escaping the atom, an ATI spectrum will consist of a sequence of equally spaced peaks at energies... 

Above-threshold ionization (ATI) refers to the probability of ionization when the laser frequency is below the ionization potential, i.e., it does not occur in linear response.Both ATI and MPI require knowledge of the correlated wave function, which is not directly available in a KS calculation, hence neither are given well in a TDDFT calculation. 

G. Gerber The observed molecular ATI (above-threshold ionization) in Na2 occurs for laser intensities above 10l2W/cm2. The observation that no additional fragmentation channels (except the 2EJ channel) open up in Na2+ might explain why in femtosecond cluster experiments additional ion fragmentation channels do not show up. Within the femtosecond interaction time even under ATI conditions the lowest Franck-Condon factor (FCF-allowed) vibrational levels are the only ones observed. At even higher intensities when multiple ionization of clusters occurs, the situation can be different. This has not yet been investigated in detail. 

ATI above-threshold ionization DEPT distortionless enhancement hy polarization... 

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