Rapid, ultra-sensitive detection of gas phase elemental mercury under atmospheric conditions using sequential two-photon laser induced fluorescence

摘要: We have examined the sensitivity of sequential two photon laser induced fluorescence (LIF) detection elemental mercury, Hg(0) in gas phase. The most sensitive approach involves an initial excitation 6(3)P1-6(1)S0 transition at 253.7 nm, followed by with a second to 7(1)S0 level. Blue shifted is observed on 6(1)P1-6(1)S0 184.9 nm. scheme, involving atomic transitions, emission from third extremely specific and precludes anything other than mercury. Using our 10 Hz system we achieved 0.1 ng m(-3) sampling rate Hz, i.e. averaging 100 shots pressure one atmosphere air. At low concentrations sampled simultaneously automated mercury analyzer (Tekran 2537A), ensure accuracy. linearity technique, generating flows containing between 1 10,000 using permeation tube dynamic dilution, but relying given Tekran levels concentration calculated dilution high levels. find that linear over five orders magnitude were able vary concentration. Our measured limits He Ar are much lower as these gases inefficient quenchers.