(Press-News.org) Ions are an essential tool in chip manufacturing, but these electrically charged atoms can also be used to produce nano-sieves with homogeneously distributed pores. A particularly large number of electrons, however, must be removed from the atoms for this purpose. Such highly charged ions either lose a surprisingly large amount of energy or almost no energy at all as they pass through a membrane that measures merely one nanometer in thickness. Researchers from the Helmholtz-Zentrum Dresden-Rossendorf (HZDR) and Vienna University of Technology (TU Wien) report in the scientific journal Physical Review Letters that this discovery is an important step towards developing novel types of electronic components made of graphene (DOI: 10.1103/PhysRevLett.112.068103).
Although highly charged ions cause damage only on a very limited area of a material surface, they do so extremely efficiently. This makes them an ideal tool for special tasks, such as perforating ultra-thin films of carbon that measure only one nanometer in thickness (one nanometer = one millionth of a millimeter). The result is a technologically usable nano-sieve that could, for example, separate different gases.
"Bombarding material with ions can be compared with striking billiard balls," according to Richard Wilhelm, doctoral candidate at the HZDR. "A professional player knows exactly at which angle he must strike the ball in order to succeed during his turn. In doing so, the player also calculates the energy that must be transmitted by a ball to one or more of the other balls." Ions behave similarly when they collide with atoms in the material. The ions gradually slow down on their path through a large number of collisions and continuously lose energy — like a bullet that penetrates a tree trunk and then comes to rest there.
For an ultra-thin material that consists of only a few atomic layers, this analogy, however, is not applicable — as the exciting results demonstrate from the latest experiments at the Ion Beam Center of HZDR. Wilhelm and his colleagues from Dresden and Vienna observed for the first time in experiments that the highly charged ions either flew through a nanomebrane virtually unaffected, or lost an astounding amount of energy in doing so. It was previously assumed, however, that ions always lose the same amount of energy on average.
In order to see this newly discovered effect at all, the membrane cannot be thicker than one nanometer — the carbon membrane, hanging freely from a carrier, was produced at the University of Bielefeld. In addition, the ions must have a high positive charge, meaning that many electrons were removed in advance. Thirty-fold charged xenon ions were used. Two different events can occur when the xenon ions hit the ultra-thin membrane. While one ion can virtually pass unimpeded between carbon atoms of the nanomembrane, a different ion might collide with one of the atoms in the material. During such a collision, it passes through the electron cloud of the atom and sucks up the negatively charged electrons. This electron capture almost leads to neutralization of the ion, resulting in a considerable deceleration. Depending on the angle at which the ion continues to travel after the collision, the energy loss amounts up to ten percent.
"Our experiments demonstrated for the first time that the energy loss in the material depends considerably on the charge state of the ions. We suspect a general relationship, which could not be previously observed with the customary thicker materials and in lower ion charge states," explains HZDR doctoral candidate Wilhelm.
Graphene the "Miracle Material"
The researchers at the Helmholtz-Zentrum Dresden-Rossendorf and Vienna University of Technology (TU Wien) would like to work with the promising material of graphene as a next step. Graphene is carbon that is only one atomic layer thick. It possesses almost exotic properties, such as extreme durability while it is also transparent and a metal. "Many groups around the world are working with graphene at the moment, but only very few are incorporating foreign atoms into the two-dimensional material. If this could be done routinely using ion implantation, it could lead to novel electronic components with unexpected capabilities," explains Richard Wilhelm. Within the Ion Beam Center of the HZDR, several more facilities are available for generating highly charged ions for experiments with graphene. The TU Wien, a long-term research partner, is again actively on board.
INFORMATION: END
Nanomaterial outsmarts ions
2014-04-22
ELSE PRESS RELEASES FROM THIS DATE:
Gym culture likened to McDonalds
2014-04-22
Visit a typical gym and you will encounter a highly standardised notion of what the human body should look like and how much it should weigh. This strictly controlled body ideal is spread across the world by large actors in the fitness industry.
A new study explores how the fitness industry in many ways resembles that of fast food. One of the authors is from the University of Gothenburg.
McDonaldisation of the gym culture is the theme of an article published in Sports, Education and Society, where Thomas Johansson, professor at the University of Gothenburg, together ...
Two genes linked to inflammatory bowel disease
2014-04-22
CINCINNATI—Inflammatory Bowel Disease (IBD), a group of chronic inflammatory disorders of the intestine that result in painful and debilitating complications, affects over 1.4 million people in the U.S., and while there are treatments to reduce inflammation for patients, there is no cure.
Now, Cincinnati Cancer Center and University of Cincinnati (UC) Cancer Institute researcher Susan Waltz, PhD, and scientists in her lab have done what is believed to be the first direct genetic study to document the important function for the Ron receptor, a cell surface protein often ...
New design for mobile phone masts could cut carbon emissions
2014-04-22
A breakthrough in the design of signal amplifiers for mobile phone masts could deliver a massive 200MW cut in the load on UK power stations, reducing CO2 emissions by around 0.5 million tonnes a year.
Funded by the Engineering and Physical Sciences Research Council (EPSRC), the Universities of Bristol and Cardiff have designed an amplifier that works at 50 per cent efficiency compared with the 30 per cent now typically achieved.
Currently, a 40W transmitter in a phone mast's base station* requires just over 130W of power to amplify signals and send them wirelessly ...
Speed-reading apps may impair reading comprehension by limiting ability to backtrack
2014-04-22
To address the fact that many of us are on the go and pressed for time, app developers have devised speed-reading software that eliminates the time we supposedly waste by moving our eyes as we read. But don't throw away your books, papers, and e-readers just yet — research suggests that the eye movements we make during reading actually play a critical role in our ability to understand what we've just read.
The research is published in Psychological Science, a journal of the Association for Psychological Science.
"Our findings show that eye movements are a crucial part ...
UV-radiation data to help ecological research
2014-04-22
Many research projects study the effects of temperature and precipitation on the global distribution of plant and animal species. However, an important component of climate research, the UV-B radiation, is often neglected. The landscape ecologists from UFZ in collaboration with their colleagues from the Universities in Olomouc (Czechia), Halle and Lüneburg have processed UV-B data from the U.S. NASA space agency in such a way that they can be used to study the influence of UV-B radiation on organisms.
The basic input data were provided by a NASA satellite that regularly, ...
A family of compact schemes with minimized dispersion and controllable dissipation was developed
2014-04-22
Spectral properties optimization is an important issue for developing schemes to resolve flow fields that are characterized by a wide range of length scales such as turbulent flows and aero acoustic phenomena. The work finished by Dr SUN Zhensheng and his ground provided a novel approach to optimize the dissipation and dispersion properties of a family of tri-diagonal compact schemes. The corresponding paper entitled "A high-resolution, hybrid compact-WENO scheme with minimized dispersion and controllable dissipation" was published in Sci China-Phys Mech Astron, 2014 Vol. ...
'Tween' television programming promotes some stereotypical conceptions of gender roles
2014-04-22
COLUMBIA, Mo. – The term "tween" denotes a child who is between the ages of 8 and 12 and is used to describe a preadolescent who is "in between" being a child and a teen. This demographic watches more television than any other age group and is considered to be a very lucrative market. Tween television programming consists of two genres: "teen scene" (geared toward girls) and "action-adventure" (geared toward boys). Researchers at the University of Missouri found that these programs could lead tweens to limit their views of their potential roles in society just as they begin ...
How often are unauthorized immigrant workers trafficked and abused?
2014-04-22
Los Angeles, CA (April 22, 2014) Labor trafficking – or recruiting a person for labor through force, fraud, or coercion for involuntary servitude, debt bondage, or even slavery – has been a difficult problem to track among undocumented migrant workers. With unique access to a "hidden population" from one of America's largest Spanish-speaking immigrant destinations, a recent study finds that more than 30% of undocumented migrant laborers in this area are victims of labor trafficking and 55% are victims of other labor abuses.
In this study, published in the May issue of ...
New tool helps doctors better predict, prevent deadly respiratory failure
2014-04-22
A new prediction tool can help doctors better identify patients who are at highest risk for respiratory failure after surgery and therefore prevent the often deadly condition, suggest data from a large multi-center study published in the May issue of Anesthesiology.
Affecting nearly 200,000 Americans a year, acute respiratory distress syndrome (ARDS) is a sudden failure of the lungs caused by a number of issues ranging from smoke inhalation to pneumonia or blood infection. High-risk patients can develop ARDS after surgery. ARDS is difficult to treat once it develops and ...
Minnesota projects offer hope and practical help to communities facing more extreme storms
2014-04-22
Recent projects in two Minnesota cities demonstrate how communities can protect themselves from worsening storms. These projects continue a ten year program in New England and the Midwest providing practical and affordable plans tailored to local conditions.
"Our goal is to help communities begin the steps to protect themselves," said program co-leader Latham Stack, of Syntectic International, Portland, OR. "It's important because storms have already worsened. We help communities move beyond feeling paralyzed from the lack of local information and the sense that the problem ...