A femtosecond is a unit of time in the International System of Units (SI) equal to 10-15 or 1⁄1 000 000 000 000 000 of a second; that is, one quadrillionth, or one millionth of one billionth, of a second. For context, a femtosecond is to a second as a second is to about 31.71 million years; a ray of light travels approximately 0.3 μm (micrometers) in 1 femtosecond, a distance comparable to the diameter of a virus.
A femtosecond is equal to 1000 attoseconds, or 1/1000 picosecond. Because the next higher SI unit is 1000 times larger, times of 10−14 and 10−13 seconds are typically expressed as tens or hundreds of femtoseconds.
|Red||~ 700–635 nm||~ 2.3–2.1 fs|
|Orange||~ 635–590 nm||~ 2.1-2.0 fs|
|Yellow||~ 590–560 nm||~ 2.0-1.9 fs|
|Green||~ 560–520 nm||~ 1.9-1.7 fs|
|Cyan||~ 520–490 nm||~ 1.7-1.6 fs|
|Blue||~ 490–450 nm||~ 1.6-1.5 fs|
|Violet||~ 450–400 nm||~ 1.5-1.3 fs|