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Reference.org
Attosecond
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<p>An attosecond (abbreviated as as) is a <a href="/facts/Unit_of_time/L9ShSGBv">unit of time</a> in the <a href="/facts/International_System_of_Units/S7YLglNz">International System of Units</a> (SI) equal to 10−18 or 1⁄1 000 000 000 000 000 000 (one quintillionth) of a <a href="/facts/Second/jtFxnJXx">second</a>. </p><p>An attosecond is to a second, as a second is to approximately 31.69 billion years. </p><p>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. </p><p>One attosecond is equal to 1000 <a href="/facts/Orders_of_magnitude_(time)/bEovB6Tp">zeptoseconds</a>, or 1/1000 <a href="/facts/Femtosecond/vaVXTVyR">femtosecond</a>. 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. </p>