Oscillator strengths for the Schumann-Runge bands of 16O2

Experimental oscillator strengths are presented for the (1-0)-(22-0) and (3-1)-(17-1) Schumann-Runge bands of ¹⁶O₂. A wavelength resolution of ~0.04 Å enabled individual rotational lines to be studied and an equivalent width data analysis method was used. The now established decrease in equivalent band oscillator strength with increased rotation is observed. The mean band oscillator strengths of this work for the (1-0)-(12-0) bands are in excellent agreement with recent ultra-high resolution absolute measurements, and the oscillator strength density is found to be continuous across the dissociation limit. The dipole moment deduced from the present oscillator strengths agrees well with recent ab initio and semi-empirical determinations.     

Separating overlapping bands in the IR spectra of polymers

Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 51, No. 1, pp. 58–63, July, 1989.     

Oscillator strengths for the Schumann-Runge bands of 16O18O

Oscillator strenghts were measured for the (2-0)–(15-0) Schumann-Runge bands of ¹⁶O¹⁸O. Individual rotational lines were studied at a resolution of ≈0.05Å. Band oscillator strenghts decrease with increasing rotation at a rate intermediate between those for ¹⁶O₂ and ¹⁸O₂. Our measurements are in good agreement with oscillator strenghts calculated using potential curves and dipole moments derived from ¹⁶O₂ measurements, and support conclusions that ¹⁶O¹⁸O plays only a minor role in the photodissociation of atmospheric O₂. Dipole moments deduced from our oscillator strenghts agree well with those obtained for ¹⁶O₂, ¹⁸O₂, as well as with recent ab initio and semi-empirical determinations.     

Absolute line strengths of phosphine gas near 5 μm

Absolute line strengths and line positions for over 200 vibration-rotation transitions of PH₃ gas were measured at 295 K, using a tunable-diode laser spectrometer. The spectral range covered was from 2153.697 to 2210.566 cm^?1. Line strength measurements were reproducible to better than 5% on average, and the uncertainty in line positions was less than 0.002 cm^?1. Certain of the PH₃ lines were pressure-broadened with H₂ gas, and the pressure-broadening coefficients were determined.     

Band strengths in forbidden transitions: The Cameron bands of CO

The band strengths of the Cameron system of CO, a³Π → X¹Σ, have been measured. The data yield an electronic oscillator strength of 1.7 × 10^-4 ± 10 per cent. The radiative lifetime depends on the rotational quantum number and estimates are made of these from published line strength formulae.     

Absolute dipole oscillator strengths for photoabsorption and photoionization of carbon disulphide

The absolute dipole oscillator strengths (cross-sections) for photoabsorption and photoionization (total and partial) of CS₂ have been obtained in the 5–40 eV energy range by magic-angle dipole (e, 2e) spectroscopy. Very strong absorption is detected below 20 eV, much of which is attributable to the excitation of molecules decaying by autoionization processes. Analysis of binding energy spectra taken at energy losses above 20 eV reveals extensive satellite structure in the range up to 35 eV. This structure is attributed to many-electron effects consistent with theoretical calculations found in the literature. Photoelectron branching ratios for CS₂ are also reported.     

Intensities of bands in the IR spectrum and conformation of polyethylene terephthalate

Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 52, No. 1, pp. 82–88, January, 1990.     

Temperature dependence of the half-width for the IR bands of cyanides and ketones

The half-width increases linearly with temperature, which is shown to be explicable only via intermolecular interaction. The lifetime of the molecules in the equilibrium state is calculated.I am indebted to I. S. Pominov for a discussion of the results.     

Separation of closely located IR Fourier absorption bands using the genetic algorithm

The genetic algorithm was used for analyzing experimental closely located analytical conformation-sensitive IR Fourier absorption bands of low-molecular compounds incorporated into a polymeric matrix. Model experiments demonstrated the efficiency of spectrum reconstruction using the genetic algorithm as compared to the least squares method in the case of closely located components and in the presence of low-frequency noise in the spectrum.     

Calculation of the intensity and dichroism of the IR absorption bands of oriented polymers

An algorithm for calculating the intensity and dichroism of polarized IR absorption bands of oriented polymers is proposed. The absorption curves in the IR spectrum of amorphous cis-1,4-polyisoprene and the dichroism of its absorption bands have been calculated. The polarization IR spectra of oriented amorphous cis-1,4-polyisoprene for a stretching ratio equal to 3 have been constructed. The calculated values of the absorption-band dichroism are in fairly good agreement with the experimental data.__________Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 72, No. 1, pp. 129–132, January–February, 2005.     

Experimental and theoretical study of the absolute intensities of the IR bands of cyclopentadiene

The system of electrooptical parameters which characterizes the polarization properties of the bonds of the cyclopentadiene molecule is calculated. The absolute intensities of the IR bands are interpreted.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii Fizika, No. 1, pp. 42–46, January, 1970.The authors thank O. S. Nikitin for assistance in the measurements.     

Rotational line strengths in the Lyman and Werner bands of H2

Rotational line strengths in the Lyman and Werner bands of molecular hydrogen are affected by the nonadiabatic interaction between the B and C states. Numerical results are presented for the effect of this interaction on relative rotational line strengths for V_x = 0 and V_B ≤ 25, V_c ≤ 9. The B-C interaction is shown to have a pronounced effect for many levels. This difference in rotational line strength factors from the usual Hönl-London factors should be taken into account when relating line oscillator strengths to band oscillator strengths. Relative rotational line strengths are also computed for transitions between C-state levels and excited vibrational levels in the X state. Comparison is made to the measured Werner band emission line intensities of Schmoranzer and Geiger [J. Chem. Phys., 59, 6153 (1973)].     

Calculation of intensities of torsional-rotational bands in the IR absorption spectrum of hydrogen peroxide

We present the calculated intensity distributions in torsional-rotational IR absorption bands of hydrogen peroxide. The torsional components of the band intensities have been calculated based on the appropriate matrix element computations. The contribution of the rotational components has been calculated using the 3j-symbols technique. The calculations have proved the reliability of available data on rotational constants, barrier heights of internal rotation, and locations of torsional-rotational levels of hydrogen peroxide. __________ Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 75, No. 2, pp. 153–158, March–April, 2008.