On extreme field limits in high power laser matter interactions: radiation dominant regimes in high intensity electromagnetic wave interaction with electrons

We discuss the key important regimes of electromagnetic field interaction with charged particles. Main attention is paid to the nonlinear Thomson/Compton scattering regime with the radiation friction and quantum electrodynamics effects taken into account. This process opens a channel of high efficiency electromagnetic energy conversion into hard electromagnetic radiation in the form of ultra short high power gamma ray flashes.Comment: 15 pages, 10 figures, invited talk presented at the SPIE-2013 conference, Prague, Czech Republic, Apr. 15, 201

The role of inertial and spatial confinement in laser interaction with organic materials

Short-pulse laser irradiation of organic material performed under conditions of inertial or spatial confinement can result in laser damage or material ejection (ablation) at relatively low laser fluences. A computational investigation of the mechanisms of the efficient transformation of the deposited laser energy into the energy of material ejection is used in this work to discuss a number of potential applications of the regime of confined laser ablation. In particular, we show that a direct irradiation of a bulk organic sample by a laser pulse performed in the regime of stress confinement can lead to the ejection of a layer of a relatively intact material with thickness determined by the laser penetration depth and fluence. Further irradiation of the spalled layer by an intense femtosecond laser pulse leads to efficient emission of picosecond bunches of energetic ions directed toward the target. In another example, a controlled deposition of functional organic molecules into a designated region of a polymer substrate is achieved by laser irradiation of a microscopic amount of molecular substance spatially confined in the tip of a micropipette. 1

The Organic Ammonium Counterion Effect on Slow Magnetic Relaxation of the [Er(hfac)₄]⁻ Complexes

The first mononuclear anionic erbium complex [Er(hfac)4]− (hfac = hexafluoroacetylacetone) with an organic ammonium cation [(CH3)4N+] as the counterion was synthesized and structurally and magnetically characterized. The coordination geometries around the Er ions are square antiprisms with pseudo-D4d symmetry. The complex shows distinct field-induced slow magnetization relaxation, which is described by a combination of Orbach (Ueff/kB~28.54(8) K.) and direct mechanisms. Quantum chemical calculations were performed to analyze the magnetic properties of the complex under consideration

Decomposition of powerful axisymmetrically polarized laser pulses in underdense plasma

Interaction of relativistically intense axisymmetrically polarized (radially or azimuthally polarized) laser pulses (RIAPLP) with underdense plasma is shown experimentally and theoretically to be essentially different from the interaction of conventional Gaussian pulses. The difference is clearly observed in distinct spectra of the side-scattered laser light for the RIAPLP and Gaussian pulses, as well as in the appearance of a spatially localized strong side emission of second harmonic of the laser pulse in the case of RIAPLP. According to our analysis based on three-dimensional particle-in-cell simulations, this is a result of instability in the propagation of RIAPLP in uniform underdense plasma