Vladimir B. Sovkov

Experimental investigation of the Rb-85(2) a (3)Sigma(+)(u) triplet ground state: Multiparameter Morse long range potential analysis

Using perturbation facilitated infrared-infrared double resonance excitation of the (85)Rb(2) molecule, we have observed spectrally resolved fluorescence to the a (3)Sigma(u)(+) state. We have analyzed the rovibrational energy level structure of the (85)Rb(2) a (3)Sigma(u)(+) state and derived a multiparameter Morse Long Range (MLR) potential and molecular constants for this state, which can be used to predict term values without needing to solve the radial Schrödinger equation.

Experimental study of the K2392Πg3 state by perturbation facilitated infrared-infrared double resonance and two-photon excitation spectroscopy

The 39K2 2 3Pi(g) state has been observed by perturbation facilitated infrared-infrared double resonance and two-photon excitations. The vibrational numbering of the 2 3Pi(g) levels was determined by resolved fluorescence into the bound levels as well as to the continuum of the a 3Sigma(u)+ state. The rotational assignment of the 2 3Pi(g) levels excited by two-photon transitions was determined from excitation frequencies and resolved fluorescence into the bound levels of the a 3Sigma(u) + and b 3Pi(u) states. Molecular constants obtained from these observed levels agree with theoretical constants.

Updated potential energy function of the Rb2 a3Σu+ state in the attractive and repulsive regions determined from its joint analysis with the 23Π0g state

We report new experimental data for the Rb2 a(3)Σu(+) and 2(3)Π0g states obtained using the Perturbation Facilitated Infrared-Infrared Double Resonance (PFIIDR) technique. The results include ro-vibrational term values of the 2(3)Π0g state and resolved fluorescence spectra of the 2(3)Π0g→a(3)Σu(+) transitions for a wide range of rotational and vibrational quantum numbers. An analysis of these data confirms the initial assignment of the transitions to the a(3)Σu(+) state reported in our earlier work [B. Beser, V. B. Sovkov, J. Bai, E. H. Ahmed, C. C. Tsai, F. Xie, L. Li, V. S. Ivanov, and A. M. Lyyra, J. Chem. Phys. 131, 094505 (2009)]. The potential energy functions of the Rb2 a(3)Σu(+) and 2(3)Π0g states are derived from a simultaneous fit of the available experimental data. The improved potential function of the Rb2 a(3)Σu(+) state spans both the attractive and repulsive regions starting with internuclear distance R ∼ 4.5 Å.

Joint analysis of the Cs 2 a 3 σ u + and 1 g (3 3 π 1g ) states

Sets of experimental data on the Cs(2) a(3)Σ(u)(+) and 1(g) (3(3)Π(1g)) states, including the bound-bound and bound-free fluorescence spectra, are analyzed simultaneously to produce the potential energy curves of both states in the form of the Morse long range multiparameter function. The attractive branch of the a(3)Σ(u)(+) state potential is improved relative to the one reported in our earlier work [F. Xie, V. B. Sovkov, A. M. Lyyra, D. Li, S. Ingram, J. Bai, V. S. Ivanov, S. Magnier, and L. Li, J. Chem. Phys. 130, 051102 (2009)], in which the data on this state alone were analyzed. Besides, the new potential of this state also includes the repulsive branch in the range spanned by the bound-free fluorescence spectra. We have not found experimental evidence of the double minimum character of the 3(3)Π(1g) state potential, predicted by ab initio calculations, at least up to v = 8. This fact testifies that the upper state observed is better described by the Hund coupling case (c), in which the case (a) electronic basis states are intermixed by the strong spin-orbit interaction.

Joint analysis of the Cs2 a3Σu+ and 1g (33Π1g) states

Sets of experimental data on the Cs(2) a(3)Σ(u)(+) and 1(g) (3(3)Π(1g)) states, including the bound-bound and bound-free fluorescence spectra, are analyzed simultaneously to produce the potential energy curves of both states in the form of the Morse long range multiparameter function. The attractive branch of the a(3)Σ(u)(+) state potential is improved relative to the one reported in our earlier work [F. Xie, V. B. Sovkov, A. M. Lyyra, D. Li, S. Ingram, J. Bai, V. S. Ivanov, S. Magnier, and L. Li, J. Chem. Phys. 130, 051102 (2009)], in which the data on this state alone were analyzed. Besides, the new potential of this state also includes the repulsive branch in the range spanned by the bound-free fluorescence spectra. We have not found experimental evidence of the double minimum character of the 3(3)Π(1g) state potential, predicted by ab initio calculations, at least up to v = 8. This fact testifies that the upper state observed is better described by the Hund coupling case (c), in which the case (a) electronic basis states are intermixed by the strong spin-orbit interaction.

Analysis of the Na2 23Σg+→a3Σu+ continua: Potentials and transition moment function

The repulsive a 3Σu+ state potential of the Na2 molecule is determined by applying the IPA (inverse perturbation approach) of V. S. Ivanov and V. B. Sovkov [Chem. Phys. 213, 295 (1996)] to the analysis of the Na2 2 2Σg+ (v=15, N=27, and v=5, N=39)→a 3Σu+ continua observed in the work of T. J. Whang et al. [J. Mol. Spectrosc. 160, 411 (1993)]. The resulting a 3Σu+ state potential is close to the ab initio potential within the experimental error, but its right branch deviates from the RKR–Le Roy–Bernstein potential function of the a 3Σu+ state shallow well reported in E.-J. Friedman-Hill and R. W. Field [J. Chem. Phys. 96, 2444 (1992)]. The transition moment function M(R) of the 2 3Σg+−a 3Σu+ transition is also obtained from the analysis of the spectra and compared to the ab initio one. The same 2 3Σg+ (v=15, N=27)→a 3Σu+ experimental spectrum is used for investigating abilities of the WKB nodes method, the FCF phase method, and the method of the accurate equation for the potential in terms of the transitio...

Split operator method for the nonadiabatic (J=0) bound states and (A←X) absorption spectrum of NO2

A split operator three-dimensional wave packet propagation method is adapted for the determination of the bound states and absorption band shape of NO2 molecule presenting a conical intersection between its ground X 2A1 and first excited A 2B2 electronic states. The numerical task, basically resting on a Fourier transform methodology, may present interesting advantages over matrix diagonalization techniques. The calculations of bound levels over a wide energy range and the absorption (A 2B2←X 2A1) band shape, extending up to 40 000 cm−1, are put on an equal footing by a nonadiabatic three-dimensional wave packet propagation using available ab initio potential energy surfaces. Good agreement is obtained when comparing the calculated absorption spectrum to experimental data in a low resolution limit. The position and amplitude of the band shape are determined within only 2 and 3% of relative error, respectively, the total width being still overestimated by about 15%. An analysis of the causes of errors is p...

New observation and combined analysis of the Cs20g−, 0u+, and 1g states at the asymptotes 6S1/2 + 6P1/2 and 6S1/2 + 6P3/2

We report on new observations of the photoassociation spectroscopy of ultracold cesium molecules using a highly sensitive detection technique and a combined analysis with all observed electronic states. The technique is achieved by directly modulating the frequency of the trapping lasers of a magneto-optical trap. New observations of the Cs2 0g(-), 0u(+), and 1g states at the asymptotes 6S1/2 + 6P1/2 and 6S1/2 + 6P3/2 are reported. The spectral range is extended to the red detuning of 112 cm(-1) below the 6S1/2 + 6P3/2 dissociation limit. Dozens of vibrational levels of the ultracold Cs2 0g(-), 0u(+), and 1g states are observed for the first time. The available experimental binding energies of these states are analyzed simultaneously in a framework of the generalized LeRoy-Bernstein theory and the almost degenerate perturbation theory by Marinescu and Dalgarno [Phys. Rev. A: At., Mol., Opt. Phys. 52, 311 (1995)]. The unique atomic-related parameter c3 governing the dispersion forces of all the molecular states is estimated as (10.29 ± 0.05) a.u.

The K239 2Σg+3 state: Observation and analysis

The K239 2Σg+3 state has been observed by perturbation-facilitated infrared-infrared double resonance spectroscopy and two-photon excitation. Resolved fluorescence spectra into the aΣu+3 state have been recorded. The observed vibrational levels have been assigned as the v=23–25, 27, 28, 31–33, 38–45, 47, and 53 levels by comparing the observed and calculated spectra of the 2Σg+3→aΣu+3 transitions. Molecular constants have been obtained using a global fitting procedure with a comprehensive set of experimental data. Fine and hyperfine splittings have been resolved in the excitation spectra. Perturbations between the 2Σg+3 and 2Πg3 states were observed. The hyperfine patterns of the 2Σg+3 levels are strongly affected by the perturbation. The perturbation-free and weakly perturbed levels follow the case bβS coupling scheme, while the perturbed levels follow case bβJ coupling. A Fermi contact constant, bF=65±10MHz, has been obtained. Intensity anomalies of rotational lines appeared both in the 2Σg+3∼2Πg3←bΠu3 ...

An IPA procedure for bound-continuum diatomic transition intensities

Abstract An inversion procedure for determining a repulsive diatomic molecule potential energy curve and a function of the electronic transition moment operator from structured bound-continuum transition intensity data is proposed. The method is based on the first-order perturbation inversion of node positions differences in an experimental spectrum and its zeroth order simulation. This approach is free from the restrictions of the RKR-like procedure of Child, Essen and Le Roy (J. Chem. Phys. 78 (1983) 6732). The method is tested for the 7 Li 2 (3 3 Π g ( ν = 17, N = 0)) → a 3 Σ u + and 7 Li 2 (3 3 Σ g + ( ν = 10, N = 10) → a 3 Σ μ + ) model bound-free transitions spectra.