کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
5429662 | 1397364 | 2011 | 20 صفحه PDF | دانلود رایگان |
A dipole-quadrupole electron-impact excitation model, consistent with molecular symmetry rules, is presented to fit ro-vibronic spectra of the hydrogen Fulcher-α Q-branch line emissions for passively measuring the rotational temperature of hydrogen neutral molecules in kinetic plasmas with the coronal equilibrium approximation. A quasi-rotational temperature and quadrupole contribution factor are adjustable parameters in the model. Quadrupole excitation is possible due to a violation of the 1st Born approximation for low to medium energy electrons (up to several hundred eV). The Born-Oppenheimer and Franck-Condon approximations are implicitly shown to hold. A quadrupole contribution of 10% is shown to fit experimental data at several temperatures from different experiments with electron energies from several to 100 eV. A convenient chart is produced to graphically determine the vibrational temperature of the hydrogen molecules from diagonal band intensities, if the ground state distribution is Boltzmann. Hydrogen vibrational modes are long-lived, surviving up to thousands of wall collisions, consistent with multiple other molecular dynamics computational results. The importance of inter-molecular collisions during a plasma pulse is also discussed.
Research Highlights⺠Previous models for excitation of the H2 Fulcher-α system have been compared. ⺠A simplified model for dipole-quadrupole rotational excitation has been derived. ⺠A simple chart is presented to determine vibrational temperatures. ⺠Guidelines for modeling H2 rotational and vibrational spectra are detailed.
Journal: Journal of Quantitative Spectroscopy and Radiative Transfer - Volume 112, Issue 5, March 2011, Pages 800-819