Remote sensing of trace methane using mobile femtosecond laser system of T&T Lab

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Authors
  1. Kamali, Y.
  2. Daigle, J.-F.
  3. Théberge, F.
  4. Chatéauneuf, M.
  5. Azarm, A.
  6. Chen, Y.
  7. Marceau, C.
  8. Lessard, S.C.
  9. Lessard, F.
  10. Roy, G.
  11. Dubois, J.
  12. Chin, S.L.
Corporate Authors
Defence R&D Canada - Valcartier, Valcartier QUE (CAN)
Abstract
Advances in the propagation of intense femtosecond laser pulses in air have shown that the laser pulse self-focused to form filaments and self-transformers into a white-light laser pulse or supercontinuum (SC) [1,2]. The high intensity inside the filament core ionizes the atmospheric molecules and produces a low density plasma (~1016cm-13) [3-6], which in turn defocuses the laser oulse. The balance between the self-focusing and defocusing limits the intensity in the filament zone to about 5x1013 W/cm2 in air [1,2,7]. This is referred to as the intensity clamping [8-10]. With this high intensity, most molecules would be ionized and dissociated into excited fragments, which emit fluorescence. Such unique features of the filament-induced fluorescence. Such unique features of the filament-induced fluorescence molecular spectra were successfully used for the detection of gaseous molecules in our laboratory such as nitrogen [11,12], halocarbons [13], methane (CH4) [14] and acetylene (C2H2)[15].The application of filament-induced fluorescence to remote sensing of nitrogen [16] and ethalnol in air [17] in combination with the traditional techniques of fluorescence spectros-copy and LIDAR (Light Detection And Ranging) have been successfully tested. However, all these tests have been performed in a laboratory environment; outdoor remote sensing of gaseous pollutants using filamentation induced fluorescence in
Report Number
DRDC-VALCARTIER-SL-2009-422 — Scientific Literature
Date of publication
22 Dec 2008
Number of Pages
4
DSTKIM No
CA033270
CANDIS No
532631
Format(s):
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