1 E-15 s
Encyclopedia
A femtosecond is the SI
unit of time equal to 10-15 of a second. That is one quadrillionth, or one millionth of one billionth of a second
. For context, a femtosecond is to a second what a second is to about 31.7 million years.
The word femtosecond is formed by the SI prefix
femto and the SI unit second. Its symbol is fs.
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.
Si
Si, si, or SI may refer to :- Measurement, mathematics and science :* International System of Units , the modern international standard version of the metric system...
unit of time equal to 10-15 of a second. That is one quadrillionth, or one millionth of one billionth of a second
Second
The second is a unit of measurement of time, and is the International System of Units base unit of time. It may be measured using a clock....
. For context, a femtosecond is to a second what a second is to about 31.7 million years.
The word femtosecond is formed by the SI prefix
SI prefix
The International System of Units specifies a set of unit prefixes known as SI prefixes or metric prefixes. An SI prefix is a name that precedes a basic unit of measure to indicate a decadic multiple or fraction of the unit. Each prefix has a unique symbol that is prepended to the unit symbol...
femto and the SI unit second. Its symbol is fs.
A femtosecond is equal to 1000 attoseconds, or 1/1000 picosecond
Picosecond
A picosecond is 10−12 of a second. That is one trillionth, or one millionth of one millionth of a second, or 0.000 000 000 001 seconds. A picosecond is to one second as one second is to 31,700 years....
. 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.
- Shorter times
- Typical time steps for molecular dynamicsMolecular dynamicsMolecular dynamics is a computer simulation of physical movements of atoms and molecules. The atoms and molecules are allowed to interact for a period of time, giving a view of the motion of the atoms...
simulations are on the order of 1 fs. - The waves of visible lightLightLight or visible light is electromagnetic radiation that is visible to the human eye, and is responsible for the sense of sight. Visible light has wavelength in a range from about 380 nanometres to about 740 nm, with a frequency range of about 405 THz to 790 THz...
oscillate with a period (reciprocal frequencyFrequencyFrequency is the number of occurrences of a repeating event per unit time. It is also referred to as temporal frequency.The period is the duration of one cycle in a repeating event, so the period is the reciprocal of the frequency...
) of about 2 femtoseconds [lambda/c = (600x10^-9)/(3x10^8) = 2.0x10^-15]. The precise period depends on the energy of the photonPhotonIn physics, a photon is an elementary particle, the quantum of the electromagnetic interaction and the basic unit of light and all other forms of electromagnetic radiation. It is also the force carrier for the electromagnetic force...
s, which determines their color. (See wave-particle duality) This time can be calculated by dividing the wavelengthWavelengthIn physics, the wavelength of a sinusoidal wave is the spatial period of the wave—the distance over which the wave's shape repeats.It is usually determined by considering the distance between consecutive corresponding points of the same phase, such as crests, troughs, or zero crossings, and is a...
of the light by the speed of lightSpeed of lightThe speed of light in vacuum, usually denoted by c, is a physical constant important in many areas of physics. Its value is 299,792,458 metres per second, a figure that is exact since the length of the metre is defined from this constant and the international standard for time...
(approximately 3 x 108 m/s) to determine the time required for light to travel that distance.- 1.3 fs – cycle time for 390 nanometer light, at the transition between violet visible light and ultravioletUltravioletUltraviolet light is electromagnetic radiation with a wavelength shorter than that of visible light, but longer than X-rays, in the range 10 nm to 400 nm, and energies from 3 eV to 124 eV...
- 2.57 fs – cycle time for 770 nanometer light, at the transition between red visible light and near-infraredInfraredInfrared light is electromagnetic radiation with a wavelength longer than that of visible light, measured from the nominal edge of visible red light at 0.74 micrometres , and extending conventionally to 300 µm...
- 1.3 fs – cycle time for 390 nanometer light, at the transition between violet visible light and ultraviolet
- 200 fs – the swiftest chemical reactionChemical reactionA chemical reaction is a process that leads to the transformation of one set of chemical substances to another. Chemical reactions can be either spontaneous, requiring no input of energy, or non-spontaneous, typically following the input of some type of energy, such as heat, light or electricity...
s, such as the reaction of pigments in an eyeHuman eyeThe human eye is an organ which reacts to light for several purposes. As a conscious sense organ, the eye allows vision. Rod and cone cells in the retina allow conscious light perception and vision including color differentiation and the perception of depth...
to light - 300 fs – the duration of a vibration of the atoms in an iodine molecule
- Longer timesPicosecondA picosecond is 10−12 of a second. That is one trillionth, or one millionth of one millionth of a second, or 0.000 000 000 001 seconds. A picosecond is to one second as one second is to 31,700 years....