spectroscopyNOW- Space nitrogen: Terahertz spectroscopy

• Author: David Bradley

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http://www.spectroscopynow.com/details/ezine/1643c9aba9e/Space-nitrogen-Terahertz-spectroscopy.html?&tzcheck=1&tzcheck=1

Triatomic

Researchers in Austria have observed rotational transitions of the nonlinear triatomic molecular anion NH2- - the amide ion - using terahertz spectroscopy in a cryogenic radio frequency ion trap. The finding could point the way to detecting nitrogen-containing molecules in space.

Astrophysicists first observed a spectral line in observational data from the Herschel Space Telescope in 2014 and suggested that it might be due to the amide ion. The observation would represented the first proof of the existence of this moiety in space. However, Roland Wester from the Institute of Ion Physics and Applied Physics at the University of Innsbruck, Austria, and his group have now shown that this assumption is incorrect.

Inbetweeners

They measured two previously unknown frequencies in the laboratory for the first time using terahertz spectroscopy - the region between microwave and infrared wavelengths. Using this region allows the rotation of very small molecules to be studied, explains Wester, adding that for larger molecules, vibrations of whole molecular groups can be determined. It is important to know the precise chemical composition of the interstellar medium (ISM) because it is here that gigantic clouds of dust and gas are drawn into clumps by gravity that ultimately lead to the birth of stars. Radio telescopes usually reveal the spectral lines of material in the ISM.

The new work by Wester's group was funded by the European Research Council ERC and involved confining chemical moieties in ion traps and exciting them terahertz radiation. "The amide ion consists of a nitrogen atom and two hydrogen atoms, looks just like water and behaves very similar in terms of quantum mechanics," explains team member Olga Lakhmanskaya. "For the first time, we directly measured the elementary excitation of the rotation of this molecule," she adds. The team also collaborated closely with theoretician Viatcheslav Kokoouline of the University of Central Florida, USA, who was a visiting professor at the University of Innsbruck at the time.

Amide no-go

The Innsbruck team has now been able to show that the spectral line measured in 2014 cannot be produced by amide ions by comparison with the data obtained from the Herschel Space Telescope. "We were able to show, with our measurements, that this tentative assignment is not correct," stresses Wester. In the Universe one can find various nitrogen molecules such as ammonia but, according to the Innsbruck experiments, it remains to be shown that the amide ion is also present. The second spectral line determined by the physicists however could assist in searching for this species in space. "We hope that in the future, with new telescopes, this line can be observed leading to its detection in space." Wester’s team now hopes to apply the new method to molecules with four or five atoms, where vibrations and rotations are much more complex than with a triatomic 

The first large-scale invisibility cloak that hides objects from visible light

James Plafke

http://www.extremetech.com/extreme/179973-the-first-large-scale-invisibility-cloak-that-hides-objects-from-visible-light
Among all of the sci-fi tech we see in movies — space and time travel, shrink rays, weaponized lasers — the invisibility cloak always seemed like the one piece of sci-fi technology that researchers could never create. Oddly, though, in recent times it has been thrust into the forefront of in-development science fiction technology. Now researchers at the University of Central Florida have managed to create a large-scale invisibility cloak that masks the spectrum of visible light. This is significant, as invisibility cloaking has previously only been possible for very specific wavelengths of radiation (say, microwaves). Visible light, which covers a broad swath of terahertz-level frequencies, has so far proven very hard to mask.

The real-life invisibility cloak is generally not what you picture when you hear the term. Generally, you picture a Harry Potter-style robe that completely erases your visual presence from an environment. In more “realistic” movies (relative to casting magic spells from a wand, at least), invisibility cloaks bend light around an object, making it look as if it’s covered in a liquid mirror. In real life, invisibility cloaks don’t come remotely close to the movies; for instance, they often tend to be solid objects that simply play perspective orreflective tricks on the eye. Now, researchers at a certain writer’s alma mater, University of Central Florida, have created a cloak that actually bends and masks visible light using a fishnet-type of metamaterial.

The metamaterial fishnet is composed of metal and dielectric composite films, created using a nanotransfer printing method. The films are layered in such a way as to create a fishnet-like pattern, which in turn allows the control of visible-spectrum light. [Research paper: DOI: 10.1002/adom.201470019]

The printed metamaterial sample is small — about 0.6 square inches (or four square centimeters) — but thanks to the fact that it’s a printing process, the UCF team feels it can print the material on a larger-scale for more practical applications, such as for use on fighter jets.

Debashis Chanda, a UCF assistant professor who led the project, noted that while invisibility cloaks won’t be on store shelves anytime soon (or ever), the team has been contacted by multiple companies looking to help fund more research on the matter. One of the interested parties is Lockheed Martin, so there is some high-profile interest behind the tech. For now, though, you shouldn’t salivate at the thought of being able to infiltrate the Monday morning meeting at work every week to find out if your coworkers are actually doing anything productive in there.