The electronic spectrum of F₂

Abstract

The absorption spectrum of F2 in the 780–1020 Å range has been photographed at sufficient resolution to allow a rotational analysis of many bands. A large number of vibrational levels of three ionic states have been observed and their rotational constants determined. Many perturbations in the rotational structure caused by the interaction between the three states have been investigated and the interaction energies determined. The rotational and vibrational structures of a few Rydberg states have also been analyzed in detail but no Rydberg series have been identified. The difficulties in assigning the observed states are discussed. A 1Σu+ – X1Σg+ emission band system has been observed in the 1100 Å region. An analysis of the bands of this system has allowed us to determine the term values and rotational constants of all the vibrational levels of the ground state with ν ≤ 22. The dissociation energy, D0(F2), is found to be greater than 12 830 and is estimated to be 12 920 ± 50 cm−1.

Accurate ab initio potential energy curve of F2. III. The vibration rotation spectrum

“…The vibration rotation spectrum had been measured in 1976 at the Herzberg Institute in Ottawa by means of highresolution electronic spectroscopy. 95 The mean absolute deviation between the 22 experimentally observed and our ab initio calculated levels turns out to be 5 -6 cm −1 . We are using the conversion factor: 1 mhartree ϵ 219.4746 cm −1 .…”

Accurate ab initio potential energy curve of F2. I. Nonrelativistic full valence configuration interaction energies using the correlation energy extrapolation by intrinsic scaling method

“…145 From the resulting fully ab initio potential energy curve of F 2 , the vibrational and rotational energy levels will then be calculated and compared with the experimentally determined spectrum. 109 The accuracy of CEEIS method can be pushed further by taking into account larger CI expansions. This would also call, however, for the use of larger basis sets and the possible accounting of smaller physical corrections such as nonadiabatic effects or spin-spin couplings.…”

“…Specifically, we calculate the potential energy curve for the dissociation of the F 2 molecule into two F atoms. Its rovibrational ground state spectrum has been accurately determined by experiment, 108,109 which allows the critical assessment of the theoretical results in all regions of the dissociation curve. While there exist numerous investigations of the nearequilibrium properties [110][111][112][113][114][115][116][117][118] and some theoretical studies of the dissociation curve, 66,68,69,71,[119][120][121][122][123][124][125][126][127][128][129] the latter has proven to be a difficult case due to the weakness of its chemical bond.…”

XUV-laser excitation of molecular fluorine

“…The range corresponds to the typical sextupled output of a pulsed dye laser, in this case with a mixture of rhodamine 590 and rhodamine 610, while scanning over its gain profile. The spectrum consists of a vibrational progression of red-shaded bands to the C 'Cz valence state in the notation of Colbourn et al [4]. The vibrational numbering is not yet established and is therefore given with an arbitrary offset n. The transition to the C 'Es, v= n A-26 state is strongest and individual spectral lines are recorded with a signal-to-noise ratio of up to 1000.…”

“…Investigations of the discrete absorption spectrum started in 1959 [ 31. The most detailed and accurate study of the extreme ultraviolet (XUV) absorption spectrum was reported by Colbourn et al [4]. In the wavelength range between 95 and 102 nm they observed several vibrational progressions, the most intense being denoted as the C '1: state.…”