engleski

Laser induced plasma plume studied by cavity ring-down spectroscopy

Laser induced plasma plume is usually studied and characterized by means of the time-resolved emission spectroscopy, fast imaging or time-of-flight mass spectrometry. When information about dark region of the plume or velocities and populations of metastable atoms or the ground state molecules are of interest some of the absorption techniques should be applied. We have been studied laser induced plasma of various metal targets (Ti, Mn) in vacuum or in the presence of a buffer gas by means of cavity ring-down spectroscopy (CRDS). Pulsed CRDS as absorption technique offers the possibility to study dynamics and the content of the plume and provide complementary information to the usual optical emission measurements. Several features of the CRDS measurements useful to determine velocities, population densities, electron densities, etc. will be presented. We have developed CRDS waveform analyses within the time windows to extract time dependent absorption. This is accompanied with simulation of the measurement process which allows us to interpret the observed lineshapes. Both single-pulse and dual-pulse laser induced plasmas have been studied and compared. Prospect for combined plume analyses by laser induced breakdown (LIBS) and CRDS will be discussed.

laser induced plasma; cavity ringdown spectroscopy

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