Metamaterials with dendriticlike structure at infrared frequencies

2007 ◽  
Vol 90 (19) ◽  
pp. 191904 ◽  
Author(s):  
Hui Liu ◽  
Xiaopeng Zhao
Keyword(s):  
Infrared Frequencies

scholarly journals A Comparison of the X-ray Spectra of Quasars and BL Lac Objects

1989 ◽  
Vol 134 ◽  
pp. 197-198
Author(s):  
D. M. Worrall ◽  
B. J. Wilkes
Keyword(s):  
Power Law ◽  
Radio Spectrum ◽  
Spectral Indices ◽  
Mean Power ◽  
Bl Lac Objects ◽  
X Ray ◽  
Bl Lac ◽  
Infrared Frequencies

Quasars with similar core-compact radio properties can be classified by their differences at optical and infrared frequencies. Their X-ray properties might be expected to be similar if the synchrotron self-Compton mechanism relates their radio and X-ray emission. We have compared the 0.2–3.5 keV mean power-law energy spectral indices, , for 4 quasar classes: 12 Highly Polarized QSOs (HPQs), 19 Flat Radio Spectrum, core-compact, low-polarization, QSOs (FRS QSOs), 24 radio-selected BL Lac objects, and 7 X-ray-selected BL Lac objects.

scholarly journals Graphene-based tunable hyperbolic microcavity

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Michał Dudek ◽  
Rafał Kowerdziej ◽  
Alessandro Pianelli ◽  
Janusz Parka
Keyword(s):  
Resonant Mode ◽  
Transverse Magnetic ◽  
Mid Infrared ◽  
Nanophotonic Devices ◽  
Wide Range ◽  
Fabry Perot ◽  
Hyperbolic Dispersion ◽  
Low Threshold ◽  
Infrared Frequencies ◽  
Infrared Wave

AbstractGraphene-based hyperbolic metamaterials provide a unique scaffold for designing nanophotonic devices with active functionalities. In this work, we have theoretically demonstrated that the characteristics of a polarization-dependent tunable hyperbolic microcavity in the mid-infrared frequencies could be realized by modulating the thickness of the dielectric layers, and thus breaking periodicity in a graphene-based hyperbolic metamaterial stack. Transmission of the tunable microcavity shows a Fabry–Perot resonant mode with a Q-factor > 20, and a sixfold local enhancement of electric field intensity. It was found that by varying the gating voltage of graphene from 2 to 8 V, the device could be self-regulated with respect to both the intensity (up to 30%) and spectrum (up to 2.1 µm). In addition, the switching of the device was considered over a wide range of incident angles for both the transverse electric and transverse magnetic modes. Finally, numerical analysis indicated that a topological transition between elliptic and type II hyperbolic dispersion could be actively switched. The proposed scheme represents a remarkably versatile platform for the mid-infrared wave manipulation and may find applications in many multi-functional architectures, including ultra-sensitive filters, low-threshold lasers, and photonic chips.

Magnetic response of dendritic structures at infrared frequencies

2006 ◽  
Vol 140 (1) ◽  
pp. 9-13 ◽  
Author(s):  
Hui Liu ◽  
Xiaopeng Zhao ◽  
Quanhong Fu
Keyword(s):  
Magnetic Response ◽  
Infrared Frequencies ◽  
Dendritic Structures

scholarly journals Characteristic infrared frequencies of rotational isomers of alkyl chlorides

1962 ◽  
Vol 18 (12) ◽  
pp. 1603-1613 ◽  
Author(s):  
J.J. Shipman ◽  
V.L. Folt ◽  
S. Krimm
Keyword(s):  
Rotational Isomers ◽  
Infrared Frequencies

Tetrachlorodibenzo-p-Dioxin Isomer Differentiation by Capillary Gas Chromatography Fourier Transform-Infrared Spectroscopy

1987 ◽  
Vol 41 (5) ◽  
pp. 809-820 ◽  
Author(s):  
James Grainger ◽  
Leslie T. Gelbaum
Keyword(s):  
Gas Chromatography ◽  
Fourier Transform ◽  
Vapor Phase ◽  
Valence Bond ◽  
Fourier Transform Infrared ◽  
Molecular Geometry ◽  
Ether Linkage ◽  
Relative Electron ◽  
Ft Ir ◽  
Infrared Frequencies

Reference infrared vapor-phase spectra of the 22 tetrachlorodibenzo-dioxin (TCDD) isomers were recorded at low microgram concentrations. These reference spectra of synthetic mixture components separated chromatographically or by spectral subtraction exhibit distinct infrared spectra for each isomer. The infrared frequencies are delineated in correlation tables and are interpreted in terms of substitution patterns which determine the strength of the ether linkage. Absorbance values in the 1330–1280 cm−1 (C-O-C asymmetric stretch) region correlate with specific substitution patterns and molecular geometry. Relative electron-withdrawing capacities for chlorinated aromatic rings in TCDD isomers were estimated on the basis of relative capacities determined for model compounds. Qualitative correlations were established between electron-withdrawing capacities and the effects of resonance and field interactions on the ether linkage absorption frequencies of individual TCDD isomers. Gas chromatography Fourier transform infrared (GC/FT-IR) isomer assignments are generally consistent with those obtained by proton Fourier transform nuclear magnetic resonance (1H FT/NMR) and flame ionization gas chromatography (GC/FID). A chromatographically independent method of assigning TCDD isomer structures on the basis of ether linkage asymmetric stretching frequencies was established by utilization of valence-bond approximations. GC/FT-IR assignments for several TCDD isomers differ from isomer assignments in previously published results. A user-generated, vapor-phase reference library, containing individual TCDD spectra and spectra of isomer pairs that are incompletely resolved on chromatographic columns, correctly identified each isomer in variety of mixtures by means of a software algorithm.

scholarly journals Aperiodic multilayer graphene based tunable and switchable thermal emitter at mid-infrared frequencies

2018 ◽  
Vol 124 (23) ◽  
pp. 233101 ◽  
Author(s):  
S. Sharifi ◽  
Y. M. Banadaki ◽  
V. F. Nezhad ◽  
G. Veronis ◽  
J. P. Dowling
Keyword(s):  
Multilayer Graphene ◽  
Mid Infrared ◽  
Thermal Emitter ◽  
Infrared Frequencies

TUNABLE COHERENT RADIATION FROM TERAHERTZ TO MICROWAVE BY MIXING TWO INFRARED FREQUENCIES IN A 47-MM-LONG GaSe CRYSTAL

2006 ◽  
Vol 16 (02) ◽  
pp. 589-595 ◽  
Author(s):  
WEI SHI ◽  
YUJIE J. DING
Keyword(s):  
Power Conversion Efficiency ◽  
Conversion Efficiency ◽  
Peak Power ◽  
Power Conversion ◽  
Coherent Radiation ◽  
Monochromatic Radiation ◽  
Frequency Tunability ◽  
Photon Conversion ◽  
Tunable Coherent Radiation ◽  
Infrared Frequencies

By mixing two infrared radiations near 1 μm in a 47-mm-long GaSe crystal, we efficiently generated a monochromatic radiation which has frequency tunability from 4.51 THz down to 53 GHz. The highest peak power produced by us is 389 W at 203 μm (1.48 THz), which corresponds to the photon conversion efficiency of 19% (the power conversion efficiency of 0.098%).

Structural and spectroscopic studies of transition metal nitrite complexes. V. Crystal structures and spectra of trans-Tetrakis(pyridine)dinitritonickel(II)-pyridine (1/2), trans-Tetrakis(4-methylpyridine)dinitritonickel(II) and trans-Tetrakis(pyrazole)-dinitritonickel(II)

1981 ◽  
Vol 34 (10) ◽  
pp. 2095 ◽  
Author(s):  
AJ Finney ◽  
MA Hitchman ◽  
CL Raston ◽  
GL Rowbottom ◽  
BW Skelton ◽  
...  
Keyword(s):  
Hydrogen Bonding ◽  
Transition Metal ◽  
Crystal Structures ◽  
Electronic Spectra ◽  
Spectroscopic Studies ◽  
Molecular Structures ◽  
Aromatic Rings ◽  
Paddle Wheel ◽  
Crystal And Molecular Structures ◽  
Infrared Frequencies

The crystal and molecular structures of the compounds [Ni(py)4(ONO)2],2py, [Ni(γmpy),(ONO)2] and [Ni(prz)4(ONO)2] are reported.�All three are trans nitrito complexes, the pyridine (py) compound containing two pyridine molecules of solvation. The aromatic rings in the first two complexes adopt 'paddle wheel' conformations with pitch angles varying between 40 and 70�. The nitrite ions are positioned so as to minimize repulsive interactions with the amines, and it seems likely that these groups bond through oxygen rather than nitrogen because this allows a lesser degree of interligand steric interference. The amine rings in [Ni(prz)4(ONO)2] are orthogonal to the plane containing the nickel and coordinated pyrazole nitrogen atoms; the nitrito groups are disordered between two inequivalent positions, each of which involves hydrogen bonding with the pyrazole NH groups. The nitrite infrared frequencies are similar to those observed for other nickel(II) nitrito complexes except that the antisymmetric NO stretching mode of one of the groups in the pyrazole complex is much lower in energy than expected, being in the range normally associated with a nitrogen-bonded or chelated nitrite group. It is suggested that this deviation may be caused by the hydrogen bonding in the complex. The electronic spectra of the compounds yield 10Dq values of 9100 and 8500 cm-1 for the nitrite ligands in [Ni(py)4(ONO)2] and Ni(prz)4(ONO)2], respectively, placing the nitrito group towards the weaker end of the spectro-chemical series.

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