Planetary nebula NGC3918, shown here, is a rare enough environment that atoms refrain from colliding long enough that scientists on Earth can study the spontaneous decay of atoms in very long-lived states.
The internal state of an atom can change by absorbing or emitting bits of light. In a warm gas or plasma the electrons are frequently shuttling back and forth from one state to another. Some of these states are longer lived than others, though, because of extenuating circumstances. For instance, many transitions from an excited state to the ground state occur in nanoseconds, but some can last for tens of seconds or longer. Measuring the true lifetime of the longer-lived of these transitions is difficult for the simple reason that ev en when a sample of atoms is dilute, an atom is being bumped so often that de-excitations come about before the state decays radiatively.
When even the best laboratory vacuum on Earth is still too crowded for making such delicate measurements, persistent scientists turn to outer space. Tomas Brage of Lund University (Lund, Sweden), Philip Judge of the High Altitude Observatory at NCAR (Boulder, CO), and Charles Proffitt of the Computer Science Corporation (Baltimore, MD) resort to viewing excited atoms in the planetary nebula NGC3 918 where, amid the wreckage of a dying star, there is enough energy to excite a toms but a density low enough (a few 1000 per cubic centimeter) that mutual pumping isn’t a problem (see image). Using the Hubble Space Telescope, the three scientists looked at the emissions of excited triply ionized nitrogen atoms and observed a lifetime of 2500 seconds for one particular hyperfine transition. Why is this state so robust?
Brage (email@example.com, 46-46-222-7724) says that angular momentum can be preserved in this transition only if, in addition to the electron emitting an ultraviolet photon, the nucleus itself flips over. Other than adding to basic knowledge about atomic physics , studies like these should provide spectroscopic information for studying the deaths of stars. (Brage et al., upcoming article in Physical Review Letters, probably 16 December; text at www.aip.org/physnews/select)
Phillip F. Schewe | AIP Bulletin
Return of the Blob: Surprise link found to edge turbulence in fusion plasma
27.05.2020 | DOE/Princeton Plasma Physics Laboratory
NIST researchers boost microwave signal stability a hundredfold
26.05.2020 | National Institute of Standards and Technology (NIST)
In living cells, enzymes drive biochemical metabolic processes enabling reactions to take place efficiently. It is this very ability which allows them to be used as catalysts in biotechnology, for example to create chemical products such as pharmaceutics. Researchers now identified an enzyme that, when illuminated with blue light, becomes catalytically active and initiates a reaction that was previously unknown in enzymatics. The study was published in "Nature Communications".
Enzymes: they are the central drivers for biochemical metabolic processes in every living cell, enabling reactions to take place efficiently. It is this very...
Early detection of tumors is extremely important in treating cancer. A new technique developed by researchers at the University of California, Davis offers a significant advance in using magnetic resonance imaging to pick out even very small tumors from normal tissue. The work is published May 25 in the journal Nature Nanotechnology.
researchers at the University of California, Davis offers a significant advance in using magnetic resonance imaging to pick out even very small tumors from...
Microelectronics as a key technology enables numerous innovations in the field of intelligent medical technology. The Fraunhofer Institute for Biomedical Engineering IBMT coordinates the BMBF cooperative project "I-call" realizing the first electronic system for ultrasound-based, safe and interference-resistant data transmission between implants in the human body.
When microelectronic systems are used for medical applications, they have to meet high requirements in terms of biocompatibility, reliability, energy...
Thomas Heine, Professor of Theoretical Chemistry at TU Dresden, together with his team, first predicted a topological 2D polymer in 2019. Only one year later, an international team led by Italian researchers was able to synthesize these materials and experimentally prove their topological properties. For the renowned journal Nature Materials, this was the occasion to invite Thomas Heine to a News and Views article, which was published this week. Under the title "Making 2D Topological Polymers a reality" Prof. Heine describes how his theory became a reality.
Ultrathin materials are extremely interesting as building blocks for next generation nano electronic devices, as it is much easier to make circuits and other...
Scientists took a leukocyte as the blueprint and developed a microrobot that has the size, shape and moving capabilities of a white blood cell. Simulating a blood vessel in a laboratory setting, they succeeded in magnetically navigating the ball-shaped microroller through this dynamic and dense environment. The drug-delivery vehicle withstood the simulated blood flow, pushing the developments in targeted drug delivery a step further: inside the body, there is no better access route to all tissues and organs than the circulatory system. A robot that could actually travel through this finely woven web would revolutionize the minimally-invasive treatment of illnesses.
A team of scientists from the Max Planck Institute for Intelligent Systems (MPI-IS) in Stuttgart invented a tiny microrobot that resembles a white blood cell...
19.05.2020 | Event News
07.04.2020 | Event News
06.04.2020 | Event News
27.05.2020 | Information Technology
27.05.2020 | Physics and Astronomy
27.05.2020 | Earth Sciences