Influence of Metal Traces on Kinetics of a Nitrogen Glow Discharge in Post-Discharge Period

journal article - other

English

The work presents results obtained during spectroscopic observations of DC flowing post-discharges of pure nitrogen plasma and nitrogen plasma containing traces of mercury. The plasma was studied by the emission spectroscopy in the range of 300 - 850 nm where three nitrogen spectral systems were identified, NO-beta bands were observed just above the noise level at the latest decay times over 35 ms. The discharge and post-discharge were studied in nitrogen with mercury traces of about 3.7 ppb. The total gas pressure was 700 Pa and the discharge current was kept at 150 mA. The relative populations of N_2 (B ^3 Pi_g), N_2 (C ^3 Pi_u) and N_2^+ (B ^2 Sigma_u^+) states were calculated in the dependence on the post-discharge time in the range of 3 - 40 ms. As the uncontrolled oxygen traces were recorded in the mercury flow, the experiment with a nitrogen-oxygen mixture at the same discharge conditions was added. The results showed strong quenching of the nitrogen pink afterglow by mercury traces. The kinetic explanation can done through a strong depopulation of the level N_2 (X ^1 Sigma_g^+, v = 19) (creating the mercury ^3 P_1 state) and of the levels N_2 (X ^1 Sigma_g^+, v = 28) or N_2 (A ^3 Sigma_u^+, v = 4) (creating the mercury ^1 S_0 state). Both mercury states are origins of the UV light emission (254 and 185 nm, resp.) that could not be detected in our experimental setup.

nitrogen post-discharge, pink afterglow, post-discharge kinetics, optical spectroscopy, mercury traces

KANICKÝ, V.; OTRUBA, V.; HRDLIČKA, A.; KRÁSENSKÝ, P.; KRČMA, F.

2007

31. 5. 2007

0267-9477

Journal of Analalytical Atomic Spectrometry

22

7

United Kingdom of Great Britain and Northern Ireland

754

760

7