Picosecond

A picosecond is an SI unit of time equal to 10⁻¹² or ¹ ₁ ₀₀₀ ₀₀₀ ₀₀₀ ₀₀₀ 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 approximately 31,689 years.

Absorption of a photon by a fluorophore takes a few picoseconds.