ATTOSECOND LIGHT PULSES. A curtailed wave pulse can be represented mathematically as the weighted sum of a number of wavetrains of various wavelengths. In this way, scientists at the Foundation for Research and Technology-Hellas (FORTH) in Crete have created light pulses less than a femtosecond (10^-15 seconds) in duration (Papadogiannis et al., Physical Review Letters, 22 November 1999). First they split a beam of light (wavelength of 800 nm ) into two parts; each of these, when sent through an argon vapor, produces sets of higher-harmonic wavetrains (at wavelengths equal to several fractions of the original 800 nm) which add together in a synchronized way to form the ultrashort wave pulse with a duration estimated to be less than 100 attoseconds. Before this the record short pulse was 4.5 fs in duration. (Physics World, Feb /pnu/2000/.)

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