Chemistry

McGill University researchers devise new technique to produce long, custom-designed DNA strands.

As the most abundant element in the universe, hydrogen might seem easy to come by, except that it’s usually bonded to oxygen in water or bound in organic compounds. Many applications, though, require pure hydrogen.

The probe of an atomic force microscope (AFM) scans a surface to reveal details at a resolution 1,000 times greater than that of an optical microscope. That makes AFM the premier tool for analyzing physical features, but it cannot tell scientists anything about chemistry. For that they turn to the mass spectrometer (MS).

Light can come in many frequencies, only a small fraction of which can be seen by humans. Between the invisible low-frequency radio waves used by cell phones and the high frequencies associated with infrared light lies a fairly wide swath of the electromagnetic spectrum occupied by what are called terahertz, or sometimes submillimeter, waves. Exploitation of these waves could lead to many new applications in fields ranging from medical imaging to astronomy, but terahertz waves have proven tricky to produce and study in the laboratory. Now, Caltech chemists have created a device that generates and detects terahertz waves over a wide spectral range with extreme precision, allowing it to be used as an unparalleled tool for measuring terahertz waves.














