An attosecond (abbreviated as as) is a

unit of time A unit of time is any particular time interval, used as a standard way of measuring or expressing duration. The base unit of time in the International System of Units (SI), and by extension most of the Western world, is the second, defined as ...

in the

International System of Units The International System of Units, internationally known by the abbreviation SI (from French ), is the modern form of the metric system and the world's most widely used system of measurement. It is the only system of measurement with official s ...

(SI) equal to 10⁻¹⁸ or ¹⁄_{1 000 000 000 000 000 000} (one quintillionth) of a

second The second (symbol: s) is a unit of time derived from the division of the day first into 24 hours, then to 60 minutes, and finally to 60 seconds each (24 × 60 × 60 = 86400). The current and formal definition in the International System of U ...

. An attosecond is to a second, as a second is to approximately 31.69 billion years. The attosecond is a tiny unit, but it has various potential applications: it can observe oscillating molecules, the chemical bonds formed by atoms in chemical reactions, and other extremely tiny and extremely fast things. One attosecond is equal to 1000 zeptoseconds, or 1/1000 femtosecond. Because the next SI unit is 1000 times larger, measurements of 10⁻¹⁷ and 10⁻¹⁶ second are typically expressed as tens or hundreds of attoseconds.

Common measurements

* 0.247 attoseconds: travel time of a

photon A photon () is an elementary particle that is a quantum of the electromagnetic field, including electromagnetic radiation such as light and radio waves, and the force carrier for the electromagnetic force. Photons are massless particles that can ...

across "the average bond length of molecular hydrogen" * 24.189... attoseconds: the atomic unit of time * 43 attoseconds: the shortest pulses of laser light yet created * 53 attoseconds: the shortest electron laser pulse ever created * 53 attoseconds: the second-shortest pulses of laser light created * 82 attoseconds (approximately):

half-life Half-life is a mathematical and scientific description of exponential or gradual decay. Half-life, half life or halflife may also refer to: Film * Half-Life (film), ''Half-Life'' (film), a 2008 independent film by Jennifer Phang * ''Half Life: ...

beryllium-8 Beryllium-8 (8Be, Be-8) is a radionuclide with 4 neutrons and 4 protons. It is an unbound resonance and nominally an isotope of beryllium. It has a half-life on the order of 8.19 seconds, decaying into two alpha particles. This has importa ...

, maximum time available for the

triple-alpha process The triple-alpha process is a set of nuclear fusion reactions by which three helium-4 nuclei (alpha particles) are transformed into carbon. In stars Helium accumulates in the cores of stars as a result of the proton–proton chain reaction a ...

for the synthesis of carbon and heavier elements in stars * 84 attoseconds: the approximate

of a neutral pion * 100 attoseconds: fastest-ever view of molecular motion * 320 attoseconds: the estimated time it takes

electrons The electron (, or in nuclear reactions) is a subatomic particle with a negative one elementary charge, elementary electric charge. It is a fundamental particle that comprises the ordinary matter that makes up the universe, along with up qua ...

to transfer between atoms

Historical development

In 2001,

Ferenc Krausz Ferenc Krausz (born 17 May 1962) is a Hungaro-Austrian physicist working in Attosecond physics, attosecond science. He is a director at the Max Planck Institute of Quantum Optics and a professor of experimental physics at the Ludwig Maximilian U ...

and his team at the Technical University of Vienna fired an ultrashort wavelength (7 femtoseconds) red laser pulse into a stream of

neon Neon is a chemical element; it has symbol Ne and atomic number 10. It is the second noble gas in the periodic table. Neon is a colorless, odorless, inert monatomic gas under standard conditions, with approximately two-thirds the density of ...

atoms, where the stripped electrons were carried by the pulse and almost immediately re-ejected into the neon nucleus. While capturing the attosecond pulse, the physicists also demonstrated its utility. They aimed attosecond and longer-wavelength red pulses at a type of krypton atom simultaneously: first, the electrons were knocked off; then, the red light pulse hit the electrons; finally, the energy was tested. Judging from the difference in the timing of these two pulses, the scientists obtained a very precise measurement of how long it took the electron to decay (how many attoseconds). Never before have scientists used such a short time scale to study the energy of electrons.

Applications

Need for more precise units

The

crystal lattice In crystallography, crystal structure is a description of ordered arrangement of atoms, ions, or molecules in a crystal, crystalline material. Ordered structures occur from intrinsic nature of constituent particles to form symmetric patterns that ...

vibrates and molecules rotate on a scale of picoseconds. The creation and breaking of chemical bonds and molecular vibration happen in femtoseconds. Observing the motion of electrons happens on the attosecond scale. The number of electrons in an atom and their configuration define an element. Because attosecond pulses are faster than the motion of electrons in atoms and molecules, attosecond provides a new tool for controlling and measuring quantum states of matter. These pulses have been used to explore the detailed physics of atoms and molecules and have potential applications in fields ranging from electronics to medicine.

Directly observing the wave oscillations of light

Using a method calle
attosecond streaking
people can see the electrical components of EM waves. Scientists start with a gas of neon atoms and ionize them with a single ultrashort burst of UV radiation measured in attoseconds. The electric field of the

infrared Infrared (IR; sometimes called infrared light) is electromagnetic radiation (EMR) with wavelengths longer than that of visible light but shorter than microwaves. The infrared spectral band begins with the waves that are just longer than those ...

can then strongly influence the motion of the electrons. The electrons will be forced up and down as the field oscillates. Depending on when the electron is released, this process will emit different final energies. The final measurement of the electron's energy, as a function of the relative delay between the two pulses, clearly shows the traces of the electric field of the attosecond pulse.

Short pulses of light

The 2023

Nobel Prize in Physics The Nobel Prize in Physics () is an annual award given by the Royal Swedish Academy of Sciences for those who have made the most outstanding contributions to mankind in the field of physics. It is one of the five Nobel Prizes established by the ...

was awarded to Pierre Agostini,

, and Anne L'Huillier for demonstrating a way to create "almost unimaginably" short pulses of light, measured in attoseconds. These pulses can be used to capture and study rapid processes inside

atom Atoms are the basic particles of the chemical elements. An atom consists of a atomic nucleus, nucleus of protons and generally neutrons, surrounded by an electromagnetically bound swarm of electrons. The chemical elements are distinguished fr ...

s, such as the behavior of electrons.

References

{{DEFAULTSORT:1 E-18 S Orders of magnitude (time)