The analysis of nitrogen rotational and vibrational bands in a helium microhollow gas discharge

Abstract

Emission spectroscopy is applied to measure the gas temperature T g and the vibrational distribution of N2 (C 3Πu) and N2 +(B 2Σu +) excited states from a helium microhollow gas discharge (MHGD) at atmospheric pressure. The rotational temperature T rot of N2 + is determined from relative intensity of the R‐branch lines of the N2 +(B 2Σu +–X 2Σg +) bands at 427.81 and 419.91 nm and the well‐known Boltzmann plot (BP). Using the same diagnostic technique, the rotationally resolved N2(C 3Πu–B 3Πg) band at 380.49 nm is used to measure T rot. Under our experimental conditions, T g is equal to T rot = 550–650 K for nitrogen molecules and shows a slight increase with the discharge current in the current range 3–10 mA. From the intensity ratio of two consecutive vibrational bands of the same sequence, the N2(C 3Πu) and N2 +(B 2Σu +) vibrational temperature T vib = 3,700–4,000 K is determined. It has been found that N2 +(B 2Σu +) ions have non‐Boltzmann distribution in the helium MHGD, while N2(C 3Πu) molecules are populated according to the Boltzmann distribution. Following the Franck–Condon principle, the vibrational distribution of the ground state of N2(X 1Σg +) molecules has been determined from the N2(C 3Πu) distribution using the inversion matrix of elements q XC(ν,ν′).

Experimental and theoretical study on emission spectra of a nitrogen photoionized plasma induced by intense EUV pulses

“…A vibrational temperature of 3358.9 K is inferred from the used ∆v = 0,±1,±2 and 3 transitions. The T v calculated with the aid of the Boltzmann plot is comparable to the results obtained using the intensity ratio of two consecutive vibrational bands of the same sequence in 2PS from a helium microwave gas discharge [19].…”

Effect of atmospheric pressure pulsed discharge spatial inhomogeneity on Ar I and H I lines: Electron number density study

“…Having in mind that rotational‐translational (R‐T) transfer coefficients become negligible if Δ E is much higher than the average kinetic energy of neutrals E kin (= kT ), Δ E has to be the same order of magnitude as E kin to consider the low R‐T lifetime. [ 21 ] In our case, the energy gap between CN rotational levels J ′ = 1 and J ′ = 17 equals ∆ E = 596 cm −1 . For the AlO(0–0) rotational levels J ′ = 17 and J ′ = 35, the gap equals ∆ E = 574 cm −1 while for the AlO(1–1) band, the energy gap between J ′ = 33 and J ′ = 49 rotational levels is ∆ E = 914 cm −1 .…”

“…Although the R‐T relaxation is a fast process requiring only several collisions, one must also consider the collisional quenching that can significantly reduce the effective lifetime of the excited state. However, the lack of data in the literature on collisional rate coefficients between AlO and argon atoms prevented us from calculating the effective lifetime of the excited state and comparing it to the R‐T lifetime, as proposed in Majstorović et al [ 21 ] for N 2 and N 2 + molecules.…”

Measurement of C2 and CH temperatures in argon‐acetylene low‐pressure microwave‐induced plasma

“…According to Pellerin et al, [6] Λ-doubling is considered using two sets of molecular constants, one for even J values and another one for odd J values, see Tables 1 and 2 in Pellerin et al [6] In the C 2 (d 3 Π g -a 3 Π u ) transition, the rotational levels 3 Π 0 , 3 Π 1 , and 3 Π 2 are present in state d as well as in state a. the SPS (0,2) band shown in Figure 2 in Majstorović et al [18] In the simple case of the angular momentum coupling, the Hönl-London (HL) factors are known analytic functions of rotational quantum numbers, which depend only on the type of electronic transition. [15,16] The transition comprises three sub-bands ( 3 Π 0 -3 Π 0 , 3 Π 1 -3 Π 1 , and 3 Π 2 -3 Π 2 ), forming two strong R and P branches and two weak Q branches (the exception is 3 Π 0 − 3 Π 0 ).…”

“…[18] Unfortunately, we do not possess information on R-T and other relevant lifetimes for C 2 and CH bands emitted from C 2 H 2 -containing microwave discharges. [18] Unfortunately, we do not possess information on R-T and other relevant lifetimes for C 2 and CH bands emitted from C 2 H 2 -containing microwave discharges.…”