Orbital angular momentum due to modes interference

We present generalized expressions to calculate the orbital angular momentum for invariant beams using scalars potentials. The solutions can be separated into transversal electric TE, transversal magnetic TM and transversal electromagnetic TE/TM polarization modes. We show that the superposition of non-paraxial vectorial beams with axial symmetry can provide a well-defined orbital angular momentum and that the modes superposition affects the angular momentum flux density. The results are illustrated and analyzed for Bessel beams.

X-ray Structure and Magnetic Properties of Heterobimetallic Chains Based on the Use of an Octacyanidodicobalt(III) Complex as Metalloligand

The assembly of [Co2III(μ-2,5-dpp)(CN)8]2− anions and [MII(CH3OH)2(DMSO)2]2+ cations resulted into the formation of two heterobimetallic 1D coordination polymers of formula [MII(CH3OH)2(DMSO)2(μ-NC)2Co2III(μ-2,5-dpp)(CN)6]n·4nCH3OH [M = CoII (1)/FeII (2) and 2,5-dpp = 2,5-bis(2-pyridyl)pyrazine. The [Co2III(μ-2,5-dpp)(CN)8]2− metalloligand coordinates the paramagnetic [MII(CH3OH)2(DMSO)2]2+ complex cations, in a bis-monodentate fashion, to give rise to neutral heterobimetallic chains. Cryomagnetic dc (1.9–300 K) and ac (2.0–13 K) magnetic measurements for 1 and 2 show the presence of Co(II)HS (1) and Fe(II)HS (2) ions (HS – high-spin), respectively, with D values of +53.7(5) (1) and −5.1(3) cm−1 (2) and slow magnetic relaxation for 1, this compound being a new example of SIM with transversal magnetic anisotropy. Low-temperature Q-band EPR study of 1 confirms that D value is positive, which reveals the occurrence of a strong asymmetry in the g-tensors and allows a rough estimation of the E/D ratio, whereas 2 is EPR silent. Theoretical calculations by CASSCF/NEVPT2 on 1 and 2 support the results from magnetometry and EPR. The analysis of the ac magnetic measurements of 1 shows that the relaxation of M takes place in the ground state under external magnetic dc fields through dominant Raman and direct spin-phonon processes.

Influence of Varying Gaps Between TMF Contacts on Constricted High Current Vacuum Arcs

The behavior of high current arcs in vacuum circuit breaker (VCB) is interesting for research and industrial development purpose which lead to further products. To improve the interruption capability of VCB, two approaches to control the arc have been proven successful. Applying transversal magnetic fields (TMF) on the arc is use for industrial VCB in medium voltage ranges. For greater gap distances the behavior of the arc is less thoroughly investigated. <br /> In this paper, the appearance of metal vapor arcs drawn by common TMF contacts in a vacuum-test-interrupter is investigated. An adapted drive mechanism enables to interrupt a fixed current with varying gaps from 5 to 25 mm and a constant opening time. Breaking operations with a 50 Hz current are observed with a high speed camera. With increasing gap distance a changed arc appearance can be observed. The goals of this work are to be understood as a feasibility study for optical evaluation methods for vacuum arcs under TMF.