14 DAY TRIAL // A new breakthrough in technology could mean a new era in studying astronomical phenomena, from the hole in the ozone layer to the birth of stars and planets, by employing an obscure wavelength of radiation, the terahertz, which lies between X-rays and microwaves.
A team at Delft University of Technology in the Netherlands have developed the pinpoint-size sensor, which detects the least explored waves of the electromagnetic spectrum, measuring molecules and gases in planets' atmospheres.
"The sensor is especially suited to detect molecules in interstellar gas clouds, but also to detect trace gases in atmospheres in planets, including our own," said instrument scientist Merlijn Hajenius of Delft's Kavli Institute of Nanoscience.
Terahertz radiation is the most common form of radiation in the universe but the least investigated one as well.
The heated detector, named "hot electron bolometer" (HEB), turns sensitive to the level of getting information on the terahertz signal.
"This latest work extends the performance of HEB mixers to higher frequencies," said electrical engineer Daniel Mittleman, of Rice University's T-ray lab.
The gold antenna of the detector picks up terahertz radiation and delivers it to the small superconducting bridge, where researchers can read the results.
The latest devices are more sensitive due to better contacts between the very thin superconducting film and the antenna.
"In Delft, we have set a world record with this detector in the frequency area above 1.5 terahertz," Hajenius said.
The first mission of a terahertz device is set for 2008: the measurement of the Earth's atmosphere on the second flight of Delft's balloon instrument, TELIS.
This research will check the hydroxyl radical and other molecules levels in the sky above Brazil, as a main phase in understanding the phenomenon of the ozone layer decrease.
The new HEAT observatory in Antarctica will employ the detectors for a detailed research of the interstellar matter of the Milky Way, especially the formation of new stars.
A satellite to be launched in 2008, Herschel Space Obervatory, is the terahertz version of the Hubble telescope.
The Atacama Large Millimeter Array, in Chile, will use terahertz wavelengths to discover objects in the very early universe.
Many everyday materials, like clothing, plastics, and wood can be peeked through by terahertz imaging, so terahertz devices can be employed to detect hidden weapons and drugs.
Materials absorb terahertz radiation at specific frequencies, depending on molecular structure, thus T-ray cameras can check the quality of drugs and foods.
"Maybe breath analysis will be a new application for terahertz spectroscopy in the future," said Hajenius.
Photo credit: TU Deft. Colored scanning electron microscope image revealing a superconducting HEB. The superconducting niobiumnitride nano-bridge is shown at the center which connects to the on-chip (partly shown) gold spiral antenna through additional contact pads. The strip covering the bridge is a left-over from the processing.