Laser-Induced Fluorescence from N₂⁺ Ions Generated by a Corona Discharge in Ambient Air

Abstract

In this work, we present the measurement of laser-induced fluorescence from N2(+) ions via the B(2)Σu(+)-X(2)Σg(+) 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 ≍10(10) 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 10(8-)10(10) cm(-3) were determined. With moderate increases in laser power and collection efficiency, ion concentrations of less than 10(6) cm(-3) may be measurable, potentially enabling applications in atmospheric standoff detection of ionizing radiation from hazardous radioactive sources.

Solution to the perturbation of LIF measurements via photodissociation, OH measurement in atmospheric‐pressure multihollow DBD

“…In plasma physics, laser-induced fluorescence (LIF) [1,2] is currently the leading method for the detection of radicals, [1,3,4] metastables [5,6] and some ions. [7,8] LIF provides high sensitivity, a low limit of detection and high…”

“…In plasma physics, laser‐induced fluorescence (LIF) [ 1,2 ] is currently the leading method for the detection of radicals, [ 1,3,4 ] metastables [ 5,6 ] and some ions. [ 7,8 ] LIF provides high sensitivity, a low limit of detection and high spatial and temporal resolution. Unfortunately, the method can be invasive, especially if high‐energy laser pulses are used, which are required in some cases for reaching a sufficient signal‐to‐noise ratio.…”

Dynamic Enhancement of Nitric Oxide Radioluminescence with Nitrogen Purge

“…In most cases, alpha contamination is surrounded by air, which typically limits the useful species to N 2 . It is the only species that both is sufficiently abundant and at the same time produces radioluminescence that it is not as strongly affected by O 2 and H 2 O quenching like radioluminescence from most other species is 18,22–25 . If, however, one can alter the atmosphere around an alpha emitter, then one is no longer limited to relying on N 2 as luminescent species.…”