The time-dependent wave function of a nanoring driven by a laser field is obtained by exploiting the symmetries\ud inherent to the system and used for studying the properties of the electromagnetic radiation emitted by the\ud nanoring as a function of the polarization state of the laser. The diffused radiation has the characteristics of\ud high-order-harmonic generation. For a noncircularly polarized laser field an extension of the expected cutoff\ud position is evident, indicating that nanorings are efficient sources of radiation. The polarization state of the\ud emitted harmonics can be opportunely controlled by varying the parameters of the pump field. The profile of\ud the absorbed angular moment shows that a magnetic moment can be induced depending on the polarization of\ud the driven field

The spectrum of radiation emitted by an electron colliding with a nucleus in the presence of a monochromatic laser field is calculated. The Coulomb potential is treated at all orders and the radiation is seen as spontaneous transition between two free states. The kinetic energy of the electron is T 9 100--3000 eV and the laser intensity I 9 101~ W/cm2; in this condition we see strong enhancement in the bremsstrahlung cross-section when the emitted frequency is an integral multiple of the laser frequency.PACS 32.80 -Photon interactions with atoms. PACS 41.70 -Particles in electromagnetic fields (including synchrotron radiation).

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We study the full quantum dynamics of a simple molecular ion driven by an intense laser field. In particular we show that the quantum nature of the nuclear dynamics affects the emitted high harmonic generation (HHG) spectra, strongly reshaping the plateau region. In fact, it is evident that the characteristic flat trend is transformed into a descending trend, with the lower harmonics being two orders of magnitude more intense than the higher harmonics. We show that this effect is more pronounced in the lighter isotopic species of H + 2 molecular ions and we also demonstrate that in this case the contribution to HHG from the antibonding electronic energetic surface is of the same order of magnitude as that from the bonding state.

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