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Vie de l'Institut - Institut de minéralogie, de physique des matériaux et de cosmochimie

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High Power Lasers in Astrobiology and Physics of Rydberg States - Svatopluk Civiš - Mercredi 3 février 2016 à 10 h 30


IMPMC - Université P. et M. Curie - 4, Place Jussieu - 75005 Paris


Salle de Conférence - Barre 22-23 - 4e étage - Salle 401

 

Svatopluk Civiš
J.Heyrovský - Institute of Physical Chemistry, AV ČR, Praha 8, Czech Republic

 
Abstract


Single ≤1 kJ pulses from a high-power laser (Prague Asterix Laser System) are focused into molecular gases to create large laser sparks. This provides a unique way to mimic the chemical effects of high-energy-density events in planetary atmospheres (cometary impact, lightning) matching the natural energy-density, its spatio-temporal evolution and plasma-volume scaling of such events in a fully-controlled laboratory environment. Some chemical reactions initiated by laser-induced dielectric breakdown (LIDB) in both pure molecular gases and mixtures related to the chemical evolution of the Earth’s early atmosphere were studied.
Time-resolved Fourier transform spectroscopy (TR-FTS) is reviewed, with emphasis on synchronous FTS using continuously scanning interferometers. By using a high-resolution Bruker IFS 120 HR, a TR-FTS method has been developed with the help of a microcontroller FPGA, where a maximum of 64 time-resolved data (interferograms) are recorded with a preset time interval in a single scan of the interferometer. The time resolution is about 1 μs, limited by the response time of the detector system used. This method has been applied for study of plasma in a positive column of discharge or laser plasma arising after irradiation of metal targets with a pulsed nanosecond ArF (ë = 193 nm) laser. The infrared atomic emission spectra of many chemical elements have been observed in the 800 – 10 000 cm-1 spectral region with a μs time profile. New atomic Rydberg transitions from highly excited states of atoms have been assigned for the first time.