The absolute number density of nitrogen dioxide(NO_2) seeded in argon is measured with cavity-enhanced laserinduced fluorescence(CELIF) through using a pulsed laser beam for the first time. The cavity ring down(CRD) signal is acquired simultaneously and used for normalizing the LIF signal and determining the relationship between the measured CELIF signal and the NO_2 number density. The minimum detectable NO_2 density down to(3.6±0.1)10~8 cm^(-3) is measured in 60 s of acquisition time by the CELIF method. The minimum absorption coefficient is measured to be(2.0±0.1)10^(-9) cm^(-1), corresponding to a noise equivalent absorption sensitivity of(2.2±0.1)10^(9) cm.^(-1)Hz^(-1/2). The experimental system demonstrated here can be further improved in its sensitivity and used for environmental monitoring of outdoor NO_2 pollution.
展开▼
机译：Laser-induced fluorescence measurements of spatially resolved OH densities in a helium plasma jet interacting with three different targets in the open air
