Experimental and theoretical study of distribution of O2 molecules over vibrational levels in O2(a 1Δg)–I mixture

Abstract

The vibrationally excited oxygen in O2(a 1Δg)–I mixture was detected by emission spectroscopy. The analysis of a luminescence spectra of oxygen molecules on O2(b 1Σg+,v′)→O2(X 3Σg−,v″) transitions has shown that vibrationally excited O2(b 1Σg+) molecules up to v=5 are generated in the active medium of chemical oxygen–iodine laser (COIL). The highest values of relative O2(b 1Σg+,v=1) population of 22±2% and O2(b 1Σg+,v=2) of 10±3.5% are reached for I2 content in an oxygen flow ≈1%. It is shown theoretically that the relative populations of O2(X 3Σg−), O2(a 1Δg), and O2(b 1Σg+) molecules at the first and the second vibrational levels are approximately equal because of fast EE energy exchange between oxygen molecules. Up to 20% of oxygen molecules in COIL active medium are vibrationally excited. Comparison of intensities of O2(b 1Σg+,v′)→O2(X 3Σg−,v″) bands has demonstrated that a few percent of O2(b 1Σg+,v) molecules are vibrationally excited with v=3, 4, or 5. It is suggested that the following pooling reaction forms them: O2(a 1Δg,v=i)+I(2P1/2)→O2(b 1Σg+,v′=i+2)+I(2P3/2), where i=1, 2, or 3.

Stimulated Raman scattering measurements of V–V transfer in oxygen

“…More recently, work in this laboratory has shown that vibrational excitation of diatomic species in high pressure, low temperature air plasmas reduces the net rate of free electron attachment to O 2 by at least three orders of magnitude [2]. Similarly, vibrational energy loading may play a critical role in a large variety of other high pressure non-equilibrium processes and systems, including plasma flow control [3], ignition and flame holding in high speed reacting flows [4], and chemical [5] and electric discharge oxygen-iodine lasers [6].…”

O2(a1Δ) quenching in the O/O2/O3 system

“…However, vibrational excitation of O 2 (a 1 D) is rapidly transferred to O 2 (X 3 R) via the fast electronic energy exchange process[32,33] O 2 ða 1 D; mÞ þ O 2 ðX 3 R; m 0 Þ $ O 2 ðX 3 R; mÞ þ O 2 ða 1 D; m 0 Þ For the conditions of our experiments, this exchange occurs on a short time-scale (%10 À8 s). Forward transfer dominated because the ratio [O 2 (X 3 R)]/[O 2 (a 1…”

Accurate ab initio intermolecular potential energy surface for the quintet state of the O2(Σg−3)–O2(Σg−3) dimer

“…5,6 Many interesting phenomena stem from the nonzero electronic spin in the ground electronic state of the monomers ͑ 3 ⌺ g − ͒ that leads to the splitting in three surfaces and, in fact, this property is meant to be exploited in an interesting emerging topic as the quest of buffer gas cooling and trapping of oxygen, [7][8][9] for which the quintet multiplicity state 10,11 plays a key role. These and many other subjects implied in this challenging system have been reviewed, for instance, in Refs.…”