A comprehensive study of the radiative properties of NO—a first step toward a complete air opacity

Abstract

In this paper we propose a methodology to calculate the radiative properties of the diatomic molecular constituents of air, and utilize the present approach to model the radiative properties of nitrogen monoxide, NO. We also investigate the important physics involved in calculating accurate radiative quantities for air, such as the Planck and Rosseland mean opacities, and emission and absorption coefficients, as well as the couplings accounted for in rovibrational calculations. Complete active space self-consistent field multi-reference configuration interaction (CAS-MRCI) calculations were performed in order to model the NO X2Π, a4Π, b4Σ-, 12Σ+, 22Σ+, 32Σ+, G2Σ-, B′2∆, (C, B) 22Π, (H′, L) 32Π, and 12Φ adiabatic states, and calculate the respective molecular data. The γ X2Π -A2Σ+, ε X2Π - D2Σ+, β′ X2Π - B′2∆, “11,000 Å” A2Σ+ - D2Σ+, “infrared” X2Π - X2Π and X2Π-(C, B) 22Π (δ and β) band systems are investigated in monochromatic spectra calculations, as well as the Ogawa a4Π- b4Σ- band and several other band systems. Several conclusions are drawn, such as the importance of including the Ogawa band, which has not been included in previous air radiative models or comprehensive line-list calculations, as well as the importance of performing coupled rovibrational line-list calculations in order to accurately calculate the Rosseland means. We also found that the additional band systems modeled here contribute significantly to the total Planck and Rosseland means.

Ab initio electronic structure analysis of ground and excited states of HfN0,+

“…The m values can be used to predict spectra, opacities, and radiative properties of molecular species and hence are often calculated using ab initio techniques. [50][51][52][53] The MRCI DMCs of the first five electronic states of HfN are given in Fig. 5.…”

Transition Energies and Line Oscillator Strengths of the C 2Π(0)-X 2Π(0–6) Absorption Bands of Nitric Oxide. A Theoretical Study

“…The calculated MQDO electronic transition moment is 0.34 a.u. This value is in good agreement with the CAS-MRCI results at the equilibrium position of Cooper (1982), 0.34 a.u., andZammit et al (2022), 0.36 a.u., and with the adjusted empirically CAS-MRCI result of 0.30 a.u. of Qu et al (2021aQu et al ( , 2021b.…”

“…Regarding the theoretical data available, our result is in reasonable good agreement with the band f -values of 0.00220 and 0.00249 reported by Galluser &Dressler (1982) andDe Vivie &Peyerimhoff (1988), respectively. Zammit et al (2022) reported a value of 0.0025 for the rotationally averaged absorption oscillator strength of the diabatic C 2 Π(0)-X 2 Π(0) transition. Therefore, the electronic transition moment, overlap integrals, and eigenvector components obtained in this work seem to be accurate.…”

“…Subsequently, Velasco et al (2010) calculated f -values for the C 2 Π(0)-X 2 Π(0-10) bands with the Molecular Quantum Defect Orbital (MQDO) approach. Very recently, Zammit et al (2022) calculated the rotationally averaged absorption oscillator strength for the C 2 Π(0)-X 2 Π(0) transition using the complete active space self-consistent field (CAS-MRCI) technique. All of the measurements and calculations so far mentioned, supplied transition oscillator strengths with vibrational but not rotational resolution.…”