In this article, an ultrathin penta-band polarization-insensitive metamaterial absorber has been presented, which consists of an array of a closed ring embedded in a tetra-arrow resonator. The proposed ultrathin (~k0/18 corresponding to the highest absorption frequency) structure exhibits five distinct absorption peaks at 3.4, 8.34, 9.46, 14.44, and 16.62 GHz with peak absorptivities of 98.6%, ...

The red quasar 3C212 (z = 1.049) is one of the most distant and most luminous AGN which has shown evidence of an X-ray warm absorber. In order to further investigate this unusual quasar, we used Chandra/ACIS-S to observe 3C212 for 19.5 ksec, resulting in a net detection of ∼ 4000 counts. The Chandra data confirm the presence of an excess absorbing column NH ≈ 4 × 10 21 cm at the quasar redshift...

This work reports plasmon enhanced photoacoustic generation by using a three dimensional plasmonic absorber. The 3D plasmonic absorber comprises a thin polymer film on glass nanopillar arrays with nanogap-rich silver nanoislands. The 3D plasmonic absorber clearly shows 24.6 times higher enhancement of photoacoustic signals at an excitation wavelength of 630 nm than a simple polymeric absorber. ...

The acoustic properties of a compound micro-perforated panel (MPP) absorber array are investigated. The absorber array consists of three parallel-arranged MPP absorbers with different cavity depths. A finite element procedure is used to simulate its acoustic behaviors under normal incidence. Experimental studies are carried out to verify the numerical simulations. Due to different reactance mat...

A fully 3-D-printed wideband metamaterial absorber, characterized by an absorptivity above 0.95 in the X and Ku-bands with a fractional bandwidth of 0.71, is presented this letter. 250 mm × sample, total thickness 6.3 (0.26?0), fabricated exploiting fused deposition modeling technique commercial filaments. To achieve absorption, hyperbolic pyramidal shape designed vertically stacking multiple r...

Through the reevaluation of Kirchhoff’s law (Robitaille P. M. L. IEEE Trans. Plasma Sci., 2003, v. 31(6), 1263–1267), Planck’s blackbody equation (Planck M. Ann. der Physik, 1901, v. 4, 553–356) loses its universal significance and becomes restricted to perfect absorbers. Consequently, the proper application of Planck’s radiation law involves the study of solid opaque objects, typically made fr...