In 1878 English photographer, Edward Muybridge published in Scientific American, a series of photographs proving that a galloping horse’s four legs are at some point all in the air. He needed to freeze the action with a shutter speed of milliseconds. Now we have laser technology that can generate light pulses that are 100 billion times faster than Muybridge’s shutter and allow us to see the details of molecules in motion. Scientists at the University of East Anglia (UEA), led by Professor Steve Meech, are using this technology to measure how energy is transferred from molecule to molecule in chemical materials.
Seeing what atoms and molecules are doing in chemical reactions in ‘slow motion’ means working at speeds of femtoseconds. A femtosecond is to a second what a second is to 32 million years. But this is the sort of speed required if chemists want to ‘freeze’ the moment when atoms and molecules come together to form new compounds. The technique, called pump-probe spectroscopy, uses lasers to flash intense pulses of light in femtoseconds, and was pioneered by Nobel Prize-winner, Professor Ahmed Zewail in the late 1980s.