High-order harmonics

Heterodyne Interferometry Using High-Order Harmonic Generation in Mixed Gases... 

The DPM was revealed to be a very robust device and is now routinely used for most of the experiments carried out on the UHI 10 TW laser chain involving ion acceleration as well as high order harmonics generation from solid targets [62],... 

Hadron therapy, 175 Heterodyne interferometry, 72 High-order harmonic generation, 65 HiPER, 124 Hollow fiber, 167 Hot electrons, 174... 

If in (4.8a) the first ionization potential E01 is neglected, the electron starts its orbit in the continuum with an initial velocity viiJ) = k + A(t ) = 0 and t, t, and k are all real inside the classically allowed region. The classical boundary then is characterized by the fact that the two solutions of the afore-mentioned pair merge. (There are no such real solutions outside the classically allowed region.) This can be exploited to obtain (approximate) closed formulas for the cutoffs (corresponding to the well known cutoff E + 3.177, for high-order harmonic generation) see [31]. 

Focusing Intense High-Order Harmonics to a Micron Spot Size... 

Fig. 9.1. Plots of measured energy of the high-order harmonics generated in xenon...

The surface accuracy of commercial mirrors is typically A/5-A/15 at 633 nm, which corresponds to A-3A wavelengths in the XUV/SXR regime. Therefore, the focused intensity together with the focusability is limited by the quality of the curved mirrors. In spite of this situation high-order harmonics can be focused down to a micrometer spot size because of the good beam quality and spatial coherence [14-16]. 

We describe in the following sections how sub-pj-level high-order harmonic beams can be well-focused to a micron spot size, resulting in intensities of 1013—1014 W/cm2. Various focusing mirrors, as shown in Table 9.1 are tested and used in the focusing experiment. 

Among several schemes used to produce femtosecond or subfemtosecond pulses in the X-ray region (Fourier synthesis, the use of two short perpendicularly polarized pulses, high-order harmonics from a nonlinear medium... 

The research areas treated in this series will be (i) atoms, molecules, and clusters in intense laser fields, (ii) control of molecules and clusters in intense laser fields, (iii) attosecond pulse generation, metrology, and applications, (iv) wavepacket control for high-order harmonics, (v) generation,... 

G. Ya Slepyan, S. A. Maksimenko, V. P. Kalosha, J. Herrmann, E. E. B. Campbell and IV. Hertel, Highly efficient high-order harmonic generation by metallic carbon nanotubes, Phys. Rev. A 60, R777-R780 (1999). 

Similar results have recently been found for hydrogen in a two-colour field [250], One possible reason for this remarkable enhancement is that in a two-colour field one specific high-order harmonic can be generated by a large number of different mixing processes [249]. 

Other interesting related phenomena, worthy of a quantum chemist s attention, are the study of the hyperpolarizabilities of molecules trapped in a cage, e.g. a zeolite [98] or on a surface [99-102], and the whole relevance of these properties to surface property calculations, where, at the local level, there are enormous electric fields. There is also the area of very high-order harmonic generation, such as can occur in very intense laser beams and where conventional perturbation theory breaks down [103]. Finally, there is magnetic non-linear optics and here the surface, computationally, has, so to speak, only been scratched. 

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