Laser-induced plasma peculiarity at low pressures from the elemental lifetime perspective.

The Laser-Induced Breakdown Spectroscopy (LIBS) plasma characteristics are known to strongly dependent on the surrounding pressure. Six different samples (C, Ni, Cu, Sn, Al, Zn) are used to support the existence of a `soft spot' in the vicinity of 1 torr where the maxima in plasma lifetime is observed. With pressure decrease, the elemental lifetimes of samples except for carbon increased until 1 torr and started to decline with continued pressure drop. The boiling point and electronegativity of the samples are amongst the physicochemical properties that are used to explain this peculiarity.