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Radiative lifetimes, transition moments, oscillator strengths and excitation probabilities for H molecule, 13, 14, 15 and 22 electron diatmoic molecules and carbon dioxide ion
Radiative lifetimes of BBr and UV emissions in electron beam excited boron trifluoride gas from phase shift measurements, discussing molecular electronic transition moments
Potassium photoionization cross section, including spin-orbit interaction, orientation of photoejected electrons and dipole transition moment correction due to core polarization
The absolute cross sections for the excitation of the NO(+) bands, two nitric oxide beta' bands, and several atomic nitrogen multiplets in the vacuum ultraviolet by electron impact on NO were measured over an energy range extending from threshold to 3000 eV. The variation of the dipole transition moment for the NO(+) band system was also determined.
The A approaches X, B approaches X and B approaches A bands of CO(+) have been excited using monochromatic photons and the band intensities measured. Using such data the variations of the electronic transition moments for these above emission bands as well as for the absorption bands have been determined. Further, the specific cross sections for the absorption processes have been determined by measuring the total emission intensity in the band system through which the upper state decays. The band intensity measurements and the derived results are presented.
The absolute cross sections for the excitation of the nitrosyl cation Baer-Miescher bands, two nitric oxide bands, and several atomic nitrogen multiplets in the vacuum UV by electron impact on NO have been measured over an energy range extending from threshold to 300 eV. The variation of the dipole transition moment for the nitrosyl cation band system was also determined.
Principal-series oscillator strengths and ground-state photoionization cross sections are computed for sodium, potassium, rubidium, and cesium. The degree of polarization of the photoelectrons is also predicted for each atom. The core-polarization correction to the dipole transition moment is included in all of the calculations, and the spin-orbit perturbation of valence-p-electron orbitals is included in the calculations of the Rb and Cs oscillator strengths and of all the photoionization cross sections. The results are compared with recent measurements.
The theory of the intensity factors of rotational lines in diatomic molecular spectra is reviewed with an emphasis on removing obscurities and resolving ambiguities that exist. For example, a unified intensity-factor sum rule is derived that is valid for all spin-allowed and spin-forbidden dipole transitions. Further, it is shown that the electronic transition moments can always be chosen to be real and that a few simple rules ensure the application of consistent phase factors.
In order to define the origins of experimentally observed predissociations within the A2 sigma/+/ state of OH, overlaps have been computed of the bound level vibrational wavefunctions in the A2 sigma/+/ state with the vibrational continua of states of OH arising from the ground electronic state separated atoms. The dependence of the transition moment upon internuclear distance is derived and compared with previous results. Implications of this analysis in terms of the two body formation of OH are indicated.
The emission spectrum of the Meinel band system of N2(+) was obtained in the region between 0.72 and 1.6 micrometers by electron impact excitation of N2. The relative excitation function is presented for the (0, 0) band from 22 to 120 eV. Cross sections of the Meinel bands that fall in this region were measured relative to the (2, 0) Meinel band. The results obtained are in good agreement with previously published values below 1.1 micrometers except for the (0, 0) band which is 30% higher. The electronic transition moment at large internuclear distances is found to agree with theoretical estimates.
The electronic states of Zn2 are investigated by ab initio polarization configuration-interaction calculations. Molecular states dissociating to Zn(1S) + Zn(1S, 3P, 1P) and Zn(3P) + Zn(3P) are treated. Important effects from states arising from Zn(+)(25) + Zn(-)(2P) are found in the potential-energy curves and electronic-transition moments. A model calculation for Hg2 based on the Zn2 curves and including spin-orbit coupling leads to a new interpretation of the emission bands in Hg vapor.
Tables of energy levels, Franck-Condon factors, r-centroids, transition moments, line wavelengths, and gf values are presented for the fourth positive system of CO.
Using the CO2 laser induced fluorescence technique at 298 K for excitation of the P(30) transition in O3 or the P(22) transition in OCS, double-quantum vibrational energy transfer was studied in the O3-CO and O3-OCS binary gas systems. Rapid rates were observed for energy transfer from the CO (nu = 1) to the coupled O3(200), O3(101), and O3(002) levels, as well as for the transfer from the coupled O3(001) and O3(100) levels to the OCS(020) level. Deactivation of OCS by N2, Ar, and OCS was studied and deactivation rate constants were measured. The experimental results are compared with those calculated using the first order perturbation theory of dipole transition-moment interactions (Sharma and Brau, 1969) as modified by Tam (1972). An attempt is made to interpret the obtained results.
The absolute intensity of the 4-0 vibration band of CO is measured in spectra obtained using a 25-m base-path multiple-traversal absorption cell and a 5-m scanning spectrometer. The intensities of individual vibration-rotation lines in this band are determined from measurements of their equivalent widths, and absolute values for the rotationless transition moment and the vibration-rotation interaction factor are derived from the measured line strengths. The experimentally obtained vibration-rotation function is compared with a theoretical curve; agreement between theory and experiment is found to be good for the P-branch but poor for the R-branch. It is noted that numerical solutions to the radial Schroedinger equation lead to vibration-rotation function values that are in good agreement with the experiment.
The spectra of vacuum ultraviolet (vuv) fluorescence resulting from the excitation of CO2 by photons from an intense line emission source at 15 wavelengths in the range 449-955 A were obtained. The vibrational population distributions for the v = 0, 1, and 2 levels of the CO(A 1Pi) fragments were obtained at several incident photon wavelengths from 700 to 923 A. At incident photon wavelengths of 901 and 923, the relative intensities of the CO(A to X) bands were determined, permitting examination of the variation of the electronic transition moment with the r centroid.
A multiconfiguration, self-consistent field plus configuration-interaction calculation has been performed on the X2-Pi and A2-Pi electronic states of ClO. The values of certain molecular properties computed from the wavefunctions agree well with those from experiment. The sum of the squares of the computed electronic transition moments between the X2-Pi and A2-Pi states at 3.07 bohr is 1.75 a.u., which corresponds to the experimental result of 1.58 plus or minus 0.20 a.u. The computed ground state dipole moment at the experimental equilibrium separation is 1.232 D, which compares well with two experimental results of 1.18 plus or minus 0.12 and 1.239 plus or minus 0.010 D. The value of the computed dissociation energy is 2.75 eV, which agrees well with the experimental value of 2.803 plus or minus 0.001 eV.
Vibration-rotation line intensities, self-broadening coefficients, and foreign-gas-broadening (Ar and N2) coefficients were measured at 197, 233, and 294 K for the 30 0 1 II--00 0 0 band of CO2 at 6348/cm. Values for the total band intensity, purely vibrational transition moment, and vibration-rotation interaction factor were deduced from the measurements.
Gases containing SiO, SiO2, SiH, and Si2 were produced in the reflected-shock region of a shock tube by heating SiCl4 + N2O + Ar and SiH4 + Ar mixtures with shock waves. Spectral absorption characteristics were measured in the 160-550 nm wavelength range and in the 2800-3600 K temperature range and compared to calculated values. The sums of the squares of electronic transition moments at equilibrium separation were derived. It was found that absorption by SiO2 and other known bands of SiO, SiH, and Si2 were too weak to be measured. The cross section of absorption by a continuum, believed due to SiH, varied from 2.5 x 10 to the -17th sq cm at 280 nm to 1.6 x 10 to the -18th sq cm at 440 nm.