<sec>Nitric oxide (NO) is one of atmospheric molecules of interest and has attracted considerable attention due to its important role in the chemical process taking place in a flow field of hypersonic vehicle, in which the thermodynamic properties are required in the calculation of the aerothermodynamic flow field. Moreover, the total internal partition function is the key to calculating the thermodynamic properties of high-temperature gases. For diatomic molecules, according to the product approximation, the total internal partition function is split into three parts: electronic, vibration and rotation partition function. In this paper, by using the quantum statistical ensemble theory based on some classical thermodynamic and statistical formulae, the thermodynamic properties of NO are analyzed and discussed.</sec><sec>Firstly, in order to obtain an accurate energy of molecule, the variational algebraic method (VAM) is employed to calculate the full vibrational energy, the resultis in good agreement with the experimental result and thus yielding the realistic predictions of the unobserved higher vibrational energy that converges to the dissociation limit. Secondly, an attempt is to use the full VAM vibrational energy, the Rydberg-Klein-Rees (RKR) vibrational energy, the simple Harmonic oscillator (SHO) model and the quantum-mechanical vibrational energy obtained by the multiconfiguration self-consistent-field (MCSCF) to calculate the vibrational partition function. Then, with the rotational contributions from the Müller-McDowell formula, the internal partition function can be determined by combining the product of electronic, vibration and rotation partition functions. Thirdly, according to the thermodynamic and statistical formulae, it is easy to calculate the internal energy, entropy and heat capacity for the NO molecule in a range of 1000-5000 K. Comparison of different calculated heat capacities with the experimental ones reveals the heat capacity, of which vibrational contributions determined by the full VAM vibrational energy accord better with the experimental ones, with the maximum relative error being no more than 2.4%, whereas it can be seen that those thermodynamic results evaluated from the SHO model attest to a failure for the summation of infinite vibrational energy. The thermodynamic results of NO may have proper applications in areas that can be of great importance in theoretical and (or) experimental aspects.</sec>
Starting from the classical expression of the rovibrational transition spectra of diatomic molecule, the Difference Converging Method (DCM) is used again to derive a new convenient and easy-to-use analytical formula for predicting the P-branch transitional spectral lines in the highly rovibrational excited states of diatomic molecule. Based on the limited experimental low-lying transition spectra the emission spectral lines up to the rotational quantum number J = 80 of (0–0) band in the A Π 3 A 2 0 + → X 3 ∑ − X 1 0 + , X 2 1 transition systems of BiLi molecule are predicted and studied. The accuracy of prediction is analyzed in detail by using the prediction error Δδ, which gives a quantitative conclusion for the reliability of prediction data. Compared the data obtained by DCM method with experimental ones, and analyzed the v E x p t − v D C M , Δ E x p t , Δ D C M , Δ δ in deeply, the results show that the DCM method can use 11 known P-branch emission spectral lines to reliably reproduce the experimental values and accurately predict the high-excited transition spectral lines which may be difficult obtained in the experiment. It provides a new method to solve the problem of lack of high excited state transition spectra of diatomic molecules and the application of molecular spectrum in other fields.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.