https://iopscience.iop.org/article/10.1070/PU1967v009n05ABEH003212/pdf

The effect of collisions on the doppler broadening of spectral lines

The cross section for the near‐resonant transfer of vibrational energy from CO2(001) to N2(0), CO2(001) + N2(0)→CO2(000) + N2(1) + ΔE, is calculated for the isotopes 14N2 (ΔE = 18 cm−1) and 15N2 (ΔE = 97 cm−1). The impact parameter (semi‐classical) approximation is used, and it is assumed that the vibrational‐energy transfer is caused by the interaction of the instantaneous CO2 dipole moment with the N2 quadrupole moment. When proper account is taken of the rotational motions of the molecules it is found that in collisions of CO2 with 14N2 only the low rotational levels of the CO2 and N2 molecules contribute to Reaction (1). In collisions of CO2 with 15N2, only those rotational levels contribute which undergo transitions cancelling most of the relatively large (97 cm−1) vibrational‐resonance defect. For 14N2 below about 1000°K, where the cross section displays a negative temperature dependence, the results are in excellent qualitative and quantitative agreement with available experimental data, with no ad...

Energy Transfer in Near‐Resonant Molecular Collisions due to Long‐Range Forces with Application to Transfer of Vibrational Energy from ν3 Mode of CO2 to N2

The frequency distributions of the first four Balmer lines broadened by the local fields of both ions and electrons in a plasma are calculated in the classical path approximation. The electron collisions are treated by an impact theory accounting for upper- and lower-level perturbations and allowing (approximately) for level splittings caused by the ion fields, finite duration of the collisions, and screening of the electron fields. Ion effects are calculated in the quasistatic, linear Stark-effect approximation, using Hooper's distribution functions, which include correlation and shielding effects to high orders. Theoretical uncertainties (mainly from the impact approximation) generally increase with density, frequency separation from the line center, and decreasing temperature. However, they only exceed \ensuremath{\sim}10% when a substantial fraction of the electrons begins to act quasistatically, and agreement with measured linewidths is within 10% in all cases.

Improved Stark profile calculations for the hydrogen lines H alpha, H beta, H gamma, and H delta.

Plasma line broadening is discussed with attention restricted to emission. The statistical theory and the impact theory are applied and discussed as to limits of each and circumstances under which each is best applied. Adiabatioity, perturber interactions, and treatment for radiating ions are expressed in mathematical formulas. The wing theorem and quantum theory are applied to achieve numerical estimates for the Balmer lines, including those with high quantum numbers. Broadening by electrons only is discussed relative to adiabatic theory and Lyman lines. Basic formulas for simultaneous broadening by ions and electrons in adiabatic approximation are presented. Plasma properties are discussed in relation to experimental determinations. (C. J. G.)

Structure of Spectral Lines from Plasmas

Thermodynamic and transport properties of high temperature equilibrium air plasmas have been calculated in a wide pressure ($0.01\div100$ atm) and temperature range ($50\div60\,000$ K). The results have been obtained by using a self-consistent approach for the thermodynamic properties and higher order approximation of the Chapman-Enskog method for the transport coefficients. Debye-Hukel corrections have been considered in the thermodynamic properties while collision integrals of charge-charge interactions have been obtained by using a screened Coulomb potential. Calculated values have been fitted by closed forms ready to be inserted in fluid dynamic codes.

Thermodynamic and transport properties in equilibrium air plasmas in a wide pressure and temperature range

The broadening of the Lyman $\ensuremath{\alpha}$ line by high-velocity charged particles is calculated in the classical path approximation without the completed-collision assumption. For noninteracting perturbers, the divergence at large impact parameters associated with usual impact theories does not arise. Interactions between the perturbers are introduced by the pair correlation function. The resulting line shape is valid for frequencies larger than those permitted by the impact theory.

Stark Broadening of Spectral Lines by High-Velocity Charged Particles

/pdf/stark-effects-in-line-broadening-22bymgawju.pdf

Stark effects in line broadening

The rapid increase in carbon dioxide in the atmosphere and its associated effects on climate change and global warming has raised the importance of monitoring carbon sequestration levels. Estimating above ground biomass (AGB) is one way of monitoring carbon sequestration in forested areas. Quantifying above ground biomass using direct methods is costly, time-consuming and, in many cases, impractical. However, remote sensing technologies such as LiDAR (Light Detection And Ranging) captures three dimensional information which can be used to perform this estimation. In particular, LiDAR can be used to estimate the diameter of a tree at breast height (DBH) and from this we can estimate its AGB. For this research we used LiDAR data, along with various Machine Learning (ML) algorithms (Multiple Linear Regression, Random Forest, Support Vector Regression and Regression Tree) to estimate DBH of cocoa trees. Various feature selection methods were used to select the most significant features for our model. The best performing algorithm was Random Forest which achieved an R2 value of 0.83 and Root Mean Square Estimate (RMSE) value of 0.062. This algorithm then estimated an AGB value of 28.75 ± 2.34 Mg/ha (Megagram per hectare). We compared this result with that obtained from locally-developed allometric equations for the same cocoa plot. The comparison proved our estimate to be 14.7% lower than the allometric equation. The results demonstrated that using ML with LiDAR measurements for AGB estimation is quite promising.

Marvin B. Lewis

Papers

Structure of Spectral Lines from Plasmas

Stark Broadening of Spectral Lines by High-Velocity Charged Particles

Stark effects in line broadening

Above Ground Biomass Estimation of a Cocoa Plantation using Machine Learning