This volume is a collection of papers presented at the Sixth International Sympo­ sium "Ultrafast Phenomena in Spectroscopy" (UPS '89) held in Neubrandenburg, GDR, August 23-26, 1989. This symposium brought together about 220 scien­ tists from 18 European countries and from overseas. The participants are active in a wide range of scientific disciplines, including physics, chemistry, biology, opto-electronics and scientific instrumentation. They share a common interest in discussing problems and perspectives of ultrafast processes at picosecond and femtosecond time scales. UPS '89 was held eleven years after the first conference of this series, which took place in Tallinn, Estonia. During this period remarkable progress has been made in this field of science and technology. Now the shortest pulses have a duration of about 5 fs, which corresponds to only about three wave periods of visible light. Other important advances concern new devices for the amplification of femtosecond light pulses to very high power. The symposium UPS '89 demonstrated this progress in generating powerful ultrashort pulses and in applying them to a wide field of science and technol­ ogy. This volume reflects this development in an impressive way. With such high-performance laser light sources, ultrafast phenomena in physics, chemistry, and biology as well as in sophisticated devices for opto-electronics and micro­ electronics have been studied extensively. This opens the way into the new field of ultrafast technology.