In this work, we present the measurement of laser-induced fluorescence from N2+ ions via the <inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="i0003-7028-69-9-1042-ilm01.tif"/> band system in the near-ultraviolet. The ions were generated continuously by a plasma glow discharge in low pressure N2 and by a corona discharge in ambient air. The fluorescence decay time was found to rapidly decrease with increasing pressure leading to an extrapolated decay rate of ≍1010 s−1 at atmospheric pressure. In spite of this quenching, we were able to observe laser induced fluorescence in ambient air by means of a time-gated spectral measurement. In the process of comparing the emission signal with that of N2 spontaneous Raman scattering, ion concentrations in ambient air of order 108-1010 cm−3 were determined. With moderate increases in laser power and collection efficiency, ion concentrations of less than 106 cm−3 may be measurable, potentially enabling applications in atmospheric standoff detection of ionizing radiation from hazardous radioactive sources.
You do not have subscription access to this journal. Cited by links are available to subscribers only. You may subscribe either as an OSA member, or as an authorized user of your institution.
Contact your librarian or system administrator
Login to access OSA Member Subscription