The hyperfine structure of the 13Δg state of Na 2

The hyperfine Hamiltonian for a homonuclear diatomic molecule was expressed in the Hund's case b βS basis. With this matrix, the hyperfine splittings for the Na 2 1 3Δ g state were theoretically calculated. The hyperfine spectra of Na 2 1 3Δ g ← b 3π 1u transitions for both high- and low-rotational quantum numbers were reanalyzed. Overall, significant results were obtained.published_or_final_versio

Laser spectroscopy of FeO: Rotational analysis of some subbands of the orange system

Extensive laser excitation spectra and rotationally resolved laser-induced fluorescence spectra have been recorded for the "orange system" of gaseous FeO in the wavelength regions 5790-6140 and 5580-5640 Å. Detailed rotational analyses have been performed for about 20 Ω′ substates lying between 16 350 and 18 550 cm -1. These are found to comprise a very severely perturbed 5Δ i excited electronic state with a bond length of about 1.69 Å (which is responsible for the parallel polarization of the electronic transition from the 5Δ i ground electronic state) and a large number of "extra" Ω substates with B′ values ranging from 0.38 to 0.50 cm -1, which almost certainly belong to high vibrational levels of lower-lying electronic states. Evidence about the natures of the "extra" states is confusing, however, with the 54FeO 56FeO isotope shifts apparently being in conflict with the patterns of vibrationally resolved laser-induced fluorescence. Every single Ω substate that has been analyzed shows rotational perturbations of varying severity. The density and magnitude of the rotational perturbations are quite exceptional for a diatomic molecule, and result in a new type of totally chaotic diatomic spectrum. There is a remarkable similarity to the visible spectrum of NO 2: in NO 2 the complications arise from the high density of perturbing ground state vibrational levels; in FeO there is a correspondingly high density of perturbing electronic states at lower energy. The great complexity of the FeO spectrum arises because the states are in an awkward intermediate spin-coupling case which still resembles Hund's case (a) but shows strong tendencies toward Hund's case (c) coupling. © 1983.link_to_subscribed_fulltex

A novel electronic-hyperfine perturbation in the C4Σ- state of VO

The hyperfine structure of the level N = 37, J = 38 1 2 in the C 4Σ -, v = 0 state of VO is anomalous as a result of an electronic perturbation. Because of the high nuclear spin of 51V (I = 7 2), the hyperfine pattern has a sufficient number of lines that it can be analyzed in detail just as if it were a rotational branch fragment containing an avoided crossing. It is shown how the coefficient of F(F + 1) in the hyperfine energy expression for the perturbing state and the perturbation matrix element can be obtained very accurately, though because the nature of the perturbing state is unknown it has not been possible to interpret the coefficient in terms of conventional hyperfine parameters in this case. The conditions for the appearance of perturbations of this type and the results to be obtained from them are discussed. © 1981.link_to_subscribed_fulltex

PERTURBATION-FACILITATED ALL-OPTICAL TRIPLE RESONANCE SPECTROSCOPY OF THE NA2 B 3-PI-U STATE

The Na2 b 3PI(u) state has been studied by the continuous wave (cw) all-optical triple resonance (AOTR) technique. The AOTR technique used here corresponds to a perturbation-facilitated optical-optical double resonance (PFOODR) excitation through A 1SIGMA(u)+ approximately b 3PI(u) mixed intermediate levels from the ground state to the 2 3PI(g) state and stimulated emission pumping (SEP) of the 2 3PI(g) --> 3PI(u) transition. This sub-Doppler high-resolution PFOODR-SEP technique has allowed us to reach many b 3PI(u) levels (OMEGA=0, 1, 2, perturbed and unperturbed, including low v below the A1 SIGMA(u)+ potential minimum and higher vibrational levels up to v = 57). Based on these new high resolution data and previous results from high resolution spectroscopy, we have determined a new set of deperturbed molecular constants from the b 3PI(u) state up to nu=57, the corresponding RKR potential energy curve and the A 1SIGMA(u)+ approximately 3PI(u) spin-orbit interaction constants. This represents an example of a powerful and general technique for observing a "dark" (e.g., triplet) perturbing state when only the "bright" (e.g., singlet) perturbed state is well known from single photon spectroscopy

The Autler�Townes Effect in Molecules: Observations, Theory, and Applications

NatuurwetenskappeInstituut Vir Teoretiese FisikaPlease help us populate SUNScholar with the post print version of this article. It can be e-mailed to: [email protected]

Spectroscopic properties of the 5Δ i ground state of FeO

Laser-induced fluorescence studies of the "orange" system of gaseous FeO were combined with analyses of the discharge emission spectrum of FeO near 1 μm (recorded at high resolution by Fourier transform spectrometry) to give spectroscopic constants for the levels v = 0-3 of the ground state of FeO. FeO is shown to have a 5Δ i ground state with r e = 1.616 A ̊ and a spin-orbit coupling constant A = -94.9 cm -1; the 5Δ 0 component shows a small Λ doubling of about 0.3 cm -1. In contrast to all the known excited states of FeO the ground state is well behaved and no local rotational perturbations were detected. Predictions are given for transition frequencies of interest in astrophysical studies of FeO. © 1982.link_to_subscribed_fulltex

CW ALL-OPTICAL TRIPLE RESONANCE SPECTROSCOPY

This paper reports for the first time continuous-wave, high-resolution, all-optical triple resonance spectroscopy. Using this technique, one can overcome the spin forbidden nature of a singlet-triplet transition and consequently unperturbed triplet rovibronic levels can be reached from a singlet ground state. This technique also facilitates state-selective population transfer to highly excited vibrational levels, both in the ground state and in excited states