Accepted
The OES of plasma jet is shown in Fig.4. Both He and Ar plasma jets are
composed with OH, N2 (C3
u-B3
g), N2
+
(B2
u-X2
g). A lot of He and Ar atom lines are
found in He plasma jet and Ar plasma jet, respectively. However, O atom emission only
exists in He plasma jet but is absent in Ar plasma jet. The intensity of N2 and N2
+
in He
plasma jet is much higher than that of Ar plasma jet. The OH and O species come from
the dissociation of oxygen and water in the open air, while N2 and N2
+
species are
generated by penning effect of metastable He/Ar. As explained before, the higher N2
+
,
N2 and O intensity in He plasma is due to the higher He metastable energy (19.82 eV
and 20.06 eV for He metastable, 11.60 eV for Ar metastable)
[23]
. The reactive species