Observation of 1D−1S forbidden optical emission of atomic oxygen in atmospheric‐pressure N2/O2 plasma jet

We observed green optical emission from an atmospheric-pressureN(2)/O(2)plasma jet. The green optical emission was composed of a line emission at lambda = 557.71 +/- 0.03 nmand a broadband component at530 <= lambda <= 560 nm. The line emission was assigned to the(1)D-(1)Sforbidden transition of atomic oxygen, whereas the broadband emission was due to the formation ofO(S-1)N(2)excimer. We measured the absolute densities ofO(S-1)andO(S-1)N(2)using a spectrograph with the absolute sensitivity calibration, and we discussed the kinetics in the green plasma jet on the basis of the absoluteO(S-1)andO(S-1)N(2)densities. According to the rate coefficients and the transition probabilities reported in literature, the present experimental results are explained if the densities ofN2(A3 n-ary sumation u+)andO(P-3)are9 x 10(13)and3 x 10(13)cm(-3), respectively.