Ask A Scientist© Physics Archive

name  	     Stanley
status       student
age          20s

Question -   What is a femtosecond laser? How does it work?
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Hi Stanley!
Nice asking that...
Femtosecond laser is an ultra-fast  radiation that
has a temporal resolution  correspondent to the
speed, or rate of some chemical reactions.
With experiments utilizing that tecnique it is possible
to observe atoms in molecules in the course of
some chemical reactions in gases, liquids
and solids, and also in catalytic processes and biological
ones.
Femtochemistry, as are called these studies, is the research
field  of Professor Ahmed H. Zewaill (CalTech) and gave
him  the 1999  Chemistry Nobel Prize.
The name Femto came from a danish word for the number
15. One femtosecond, the unit used to measure the
speed of  some chemistry reactions (or transient stages)
is  equal to 10 to minus 15.
Thanks for asking NEWTON!
Mabel
(Dr. Mabel Rodrigues)
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I'm not a physicist;  I can only answer half of your question.  A
"femtosecond laser" is a laser that can produce a pulse of photons that is
shorter than a nanosecond.  (A nanosecond is 1000 femtoseconds.)  How such
lasers are constructed and how they work I don't know.  They are used to
probe very fast chemical reactions, such as the breaking of bonds between
atoms.

Richard E. Barrans Jr., Ph.D.
Assistant Director, PG Research Foundation
Darien, IL USA
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