Novel control of plasma expansion direction aimed at very low pressure laser-induced plasma spectroscopy.
Opt Express
; 23(5): 6336-44, 2015 Mar 09.
Article
en En
| MEDLINE
| ID: mdl-25836854
A plasma confinement approach has been applied to enhance the signal intensity of laser-induced plasma in low pressure conditions down to 10(-2) torr. Detection of plasma emission spectrum is a daunting task at low pressure due to the low electron density and the short persistence time of plasma that undergoes a rapid expansion. Here we devised a spatial confinement setup that increases the electron density at various range of low pressures. A confining window is placed above the sample surface to control the direction of the expanding plasma aimed at optimizing the efficiency of the low pressure detection. More ions, atoms, and molecules can reach the detector by a direction-controlled confinement of an otherwise freely expanding plasma. The spectral intensities of neutral atoms increased up to 4 times with a single laser pulse by the proposed confining method at 1 torr. The signal of doubly ionized carbon atom which was detectable only at low pressure is also enhanced 4 times. The results of this study provide an important guideline for strengthening the otherwise weak signals at low pressure by controlling the plasma expansion direction.
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01-internacional
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MEDLINE
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En
Revista:
Opt Express
Asunto de la revista:
OFTALMOLOGIA
Año:
2015
Tipo del documento:
Article
Pais de publicación:
Estados Unidos