Direct detection of evanescent electromagnetic waves at a planar dielectric surface by laser atomic spectroscopy

In this study, we examine the statistical properties of asymmetric surface dielectric barrier discharges (SDBD) produced by applying a periodic high voltage between two conducting displaced electrodes, located at the opposite sides of a flat dielectric panel. Here, the asymmetry refers to the fact that the lower electrode is fully covered with an insulating material, while the upper one, glued onto the dielectric surface, is otherwise left exposed to the air. Such a configuration allows the formation of a thin layer of plasma above the insulating surface. A single cycle signal consists of two well-separated half-cycle patterns, denoted as forward and backward strokes, corresponding to positive and negative voltages, respectively. They display a quite complex discharge pattern constituted by a sequence of individual peaks (bursts) of varying current and time duration. Specifically, we find that backward stroke bursts carry a positive mean charge Q≃0.3 nC and mean current I≃35 mA, with a mean duration τ≃15 ns, while forward stroke bursts have a negative mean charge Q≃−0.1 nC, a mean current I≃−20 mA, and a mean duration τ≃11 ns. The statistical analysis suggests that power injection can be tailored to produce the active agents in the plasma needed for a particular application. We also determined discharge spatial correlation patterns from measurements of the associated stimulated optical emission. The optical excitations occur as a result of the ionizing effect of the electromagnetic waves which ignite the discharge, followed by the electric current flow. In particular, we point out that one of the phases of the discharge is compatible with a cathode directed streamer phenomenon (backward stroke), while the mechanism acting for a forward stroke has a different structure.

Download Full-text

Terahertz Detection of Zika Viruses

10.20944/preprints202002.0232.v1 ◽

2020 ◽

Author(s):

Subhashish Dolai ◽

Massood Tabib-Azar

Keyword(s):

Electromagnetic Waves ◽

Direct Detection ◽

Petri Dish ◽

Label Free ◽

Low Loss ◽

Terahertz Detection ◽

Label Free Detection ◽

Terahertz Transmission ◽

First Time ◽

Thick Glass

Our main objective in this work was to examine the possibility of non-intrusive, label-free, detection of whole Zika viruses using terahertz signals with or without a targeting/binding oligonucleotide (aptamers). We report for the first time the use of terahertz electromagnetic waves (0.75 THz – 1.1 THz) to detect Zika viruses. The Zika/aptamer complexes showed a reproducible terahertz reflection coefficient minimum at 1.064 THz while the Zika virus’s reflection minimum was at 1.073 THz. Of different substrates we examined, the polyester petri dish provided a very low loss and excellent terahertz transmission. To increase the interaction between the terahertz signal and the sample we also used polyester microbeads coated with aptamers. We then measured the terahertz reflection from the microbeads as a function of Zika concentration. The resulting terahertz Zika sensor had sensitivity of 63 Hz/Zika and minimum detectable signal of ~ 16x103 Zika. Other substrates such as Graphene on polyethylene terephthalate (PET), 50 nm-thick gold film on polycarbonate, thin (30 um-thick) glass slide and Teflon were also examined. Graphene substrate enabled direct detection of the Zika without any aptamers.

Download Full-text

Terahertz coherent receiver using a single resonant tunnelling diode

Scientific Reports ◽

10.1038/s41598-019-54627-8 ◽

2019 ◽

Vol 9 (1) ◽

Cited By ~ 4

Author(s):

Yousuke Nishida ◽

Naoki Nishigami ◽

Sebastian Diebold ◽

Jaeyoung Kim ◽

Masayuki Fujita ◽

...

Keyword(s):

Electromagnetic Waves ◽

Motor Vehicle ◽

Direct Detection ◽

Detection System ◽

Coherent Detection ◽

Electronic Systems ◽

Resonant Tunnelling ◽

Wide Range ◽

Coherent Receiver ◽

Resonant Tunnelling Diode

AbstractTowards exploring advanced applications of terahertz (THz) electromagnetic waves, great efforts are being applied to develop a compact and sensitive THz receiver. Here, we propose a simple coherent detection system using a single resonant tunnelling diode (RTD) oscillator through self-oscillating mixing with an RTD oscillator injection-locked by a carrier wave. Coherent detection is successfully demonstrated with an enhancement in the sensitivity of >20 dB compared to that of direct detection. As a proof of concept, we performed THz wireless communications using an RTD coherent receiver and transmitter. We achieved 30-Gbit/s real-time error-free transmission, which is the highest among all electronic systems without error correction to date. Our results show that the proposed system can reduce the size and power consumption of various THz systems including sensing, imaging and ranging, which would enable progress to be made in a wide range of fields in such as material science, medicine, chemistry, biology, physics, astronomy, security, robotics and motor vehicle.

Download Full-text

Seti Space Missions

International Astronomical Union Colloquium ◽

10.1017/s0252921100015372 ◽

1997 ◽

Vol 161 ◽

pp. 761-776 ◽

Cited By ~ 1

Author(s):

Claudio Maccone

Keyword(s):

Electromagnetic Waves ◽

Space Missions ◽

Gravitational Lens ◽

The Sun ◽

Space Antenna ◽

Focal Distance ◽

Large Space ◽

The Earth ◽

Space Antennas ◽

New Space

AbstractSETI from space is currently envisaged in three ways: i) by large space antennas orbiting the Earth that could be used for both VLBI and SETI (VSOP and RadioAstron missions), ii) by a radiotelescope inside the Saha far side Moon crater and an Earth-link antenna on the Mare Smythii near side plain. Such SETIMOON mission would require no astronaut work since a Tether, deployed in Moon orbit until the two antennas landed softly, would also be the cable connecting them. Alternatively, a data relay satellite orbiting the Earth-Moon Lagrangian pointL2would avoid the Earthlink antenna, iii) by a large space antenna put at the foci of the Sun gravitational lens: 1) for electromagnetic waves, the minimal focal distance is 550 Astronomical Units (AU) or 14 times beyond Pluto. One could use the huge radio magnifications of sources aligned to the Sun and spacecraft; 2) for gravitational waves and neutrinos, the focus lies between 22.45 and 29.59 AU (Uranus and Neptune orbits), with a flight time of less than 30 years. Two new space missions, of SETI interest if ET’s use neutrinos for communications, are proposed.

Download Full-text

Detection and Characterization of earth-like Planets

International Astronomical Union Colloquium ◽

10.1017/s0252921100014810 ◽

1997 ◽

Vol 161 ◽

pp. 299-311 ◽

Cited By ~ 22

Author(s):

Jean Marie Mariotti ◽

Alain Léger ◽

Bertrand Mennesson ◽

Marc Ollivier

Keyword(s):

Direct Detection ◽

Contrast Ratio ◽

Angular Size ◽

Physical Nature ◽

Major Axis ◽

Infrared Emission ◽

Space Technology ◽

Semi Major Axis ◽

Earth Like Planets ◽

Visible Wavelengths

AbstractIndirect methods of detection of exo-planets (by radial velocity, astrometry, occultations,...) have revealed recently the first cases of exo-planets, and will in the near future expand our knowledge of these systems. They will provide statistical informations on the dynamical parameters: semi-major axis, eccentricities, inclinations,... But the physical nature of these planets will remain mostly unknown. Only for the larger ones (exo-Jupiters), an estimate of the mass will be accessible. To characterize in more details Earth-like exo-planets, direct detection (i.e., direct observation of photons from the planet) is required. This is a much more challenging observational program. The exo-planets are extremely faint with respect to their star: the contrast ratio is about 10−10at visible wavelengths. Also the angular size of the apparent orbit is small, typically 0.1 second of arc. While the first point calls for observations in the infrared (where the contrast goes up to 10−7) and with a coronograph, the latter implies using an interferometer. Several space projects combining these techniques have been recently proposed. They aim at surveying a few hundreds of nearby single solar-like stars in search for Earth-like planets, and at performing a low resolution spectroscopic analysis of their infrared emission in order to reveal the presence in the atmosphere of the planet of CO H2O and O3. The latter is a good tracer of the presence of oxygen which could be, like on our Earth, released by biological activity. Although extremely ambitious, these projects could be realized using space technology either already available or in development for others missions. They could be built and launched during the first decades on the next century.

Download Full-text

Atomic Spectroscopy in the FIM

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100145157 ◽

1986 ◽

Vol 44 ◽

pp. 758-761

Author(s):

J. J. Hren ◽

S. D. Walck

Keyword(s):

Electron Microscope ◽

Electric Fields ◽

Atom Probe ◽

Atomic Spectroscopy ◽

Single Atom ◽

Statistical Sampling ◽

Commercial Instrument ◽

Available Technology ◽

High Electric Fields ◽

Field Ion Microscope

The field ion microscope (FIM) has had the ability to routinely image the surface atoms of metals since Mueller perfected it in 1956. Since 1967, the TOF Atom Probe has had single atom sensitivity in conjunction with the FIM. “Why then hasn't the FIM enjoyed the success of the electron microscope?” The answer is closely related to the evolution of FIM/Atom Probe techniques and the available technology. This paper will review this evolution from Mueller's early discoveries, to the development of a viable commercial instrument. It will touch upon some important contributions of individuals and groups, but will not attempt to be all inclusive. Variations in instrumentation that define the class of problems for which the FIM/AP is uniquely suited and those for which it is not will be described. The influence of high electric fields inherent to the technique on the specimens studied will also be discussed. The specimen geometry as it relates to preparation, statistical sampling and compatibility with the TEM will be examined.

Download Full-text

Microwaves: Application in Electron Microscopy

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100158248 ◽

1990 ◽

Vol 48 (3) ◽

pp. 140-141

Author(s):

Anthony S-Y Leong ◽

David W Gove

Keyword(s):

Electron Microscopy ◽

Light Microscopy ◽

Chemical Reactions ◽

Electromagnetic Waves ◽

Tissue Fixation ◽

Primary Method ◽

Dipolar Molecules ◽

Wide Range ◽

Time Required ◽

Cryostat Sections

Microwaves (MW) are electromagnetic waves which are commonly generated at a frequency of 2.45 GHz. When dipolar molecules such as water, the polar side chains of proteins and other molecules with an uneven distribution of electrical charge are exposed to such non-ionizing radiation, they oscillate through 180° at a rate of 2,450 million cycles/s. This rapid kinetic movement results in accelerated chemical reactions and produces instantaneous heat. MWs have recently been applied to a wide range of procedures for light microscopy. MWs generated by domestic ovens have been used as a primary method of tissue fixation, it has been applied to the various stages of tissue processing as well as to a wide variety of staining procedures. This use of MWs has not only resulted in drastic reductions in the time required for tissue fixation, processing and staining, but have also produced better cytologic images in cryostat sections, and more importantly, have resulted in better preservation of cellular antigens.

Download Full-text