Structure of excitation and fluorescence spectra recorded at the {sup 1}0{sub u}{sup +}(5 {sup 1}P{sub 1})-X {sup 1}0{sub g}{sup +} transition of Cd{sub 2}

Journal Article · Wed Oct 01 04:00:00 EDT 2003 · Physical Review. A

DOI:https://doi.org/10.1103/PhysRevA.68.042508· OSTI ID:20640326

Lukomski, M; Koperski, J ^[1]; Czuchaj, E ^[2]; Czajkowski, M ^[3]

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1. Instytut Fizyki, Uniwersytet Jagiellonski, ul. Reymonta 4, 30-059 Krakow (Poland)
2. Instytut Fizyki Teoretycznej i Astrofizyki, Uniwersytet Gdanski, ul. Wita Stwosza 57, 80-952 Gdansk (Poland)
3. Department of Physics, University of Windsor, Windsor, Ontario N9B3P4 (Canada)

Excitation and fluorescence ultraviolet spectra of Cd{sub 2} recorded at the {sup 1}0{sub u}{sup +}(5 {sup 1}P{sub 1})-X {sup 1}0{sub g}{sup +} transition are reported. The Cd{sub 2} molecules (seeded in Ar) produced in a continuous free-jet supersonic beam were excited in a vacuum chamber with a pulsed dye-laser beam. A well-resolved vibrational structure of the {sup 1}0{sub u}{sup +} <- X {sup 1}0{sub g}{sup +} excitation spectrum as well as the isotopic structure of the vibrational components were recorded. Analysis of the spectrum yielded vibrational constants for the {sup 1}0{sub u}{sup +} state: {omega}{sub e}{sup '}=100.50{+-}0.25 cm{sup -1}, {omega}{sub e}{sup '}x{sub e}{sup '}=0.325{+-}0.003 cm{sup -1}, D{sub 0}{sup '}=8638{+-}15 cm{sup -1}, D{sub e}{sup '}=8688{+-}15 cm{sup -1}, and {delta}R{sub e}=R{sub e}{sup ''}-R{sub e}{sup '}=1.04{+-}0.01 A derived for the {sup 226}Cd{sub 2} isotopomer. The {sup 1}0{sub u}{sup +} state potential-energy (PE) curve was obtained numerically using an inverse perturbation approach (IPA) procedure. Condon internal diffraction (CID) patterns in the {sup 1}0{sub u}{sup +}{yields}X {sup 1}0{sub g}{sup +} fluorescence band, emitted upon the selective excitation of the v{sup '}=38 and v{sup '}=39 vibrational components of the {sup 226}Cd{sub 2} isotopomer, were observed and improved the v{sup '} assignments derived from the analysis of the isotopic structure. Analysis of the fluorescence spectrum yielded information on the repulsive part of the ground-state interatomic potential. The result confirms a relatively soft repulsion between two Cd atoms in the short-range (2.53-4.05 A) region and makes allowance for a covalent admixture to the ground-state van der Waals bonding. Quasirelativistic valence ab initio calculations on the PE curves for the investigated states have been performed at the complete-active-space multiconfiguration self-consistent-field (CASSCF/CAS) multireference second-order perturbation theory (CASPT2) level with the total of 40 correlated electrons. In the calculations, the Cd atom is considered as a 20-valence electron system whereas the Cd{sup 20+} core is replaced by an energy-consistent pseudopotential which also accounts for scalar-relativistic effects and spin-orbit interaction within the valence shell. A comparison with results obtained from other experiments and ab initio calculations is presented.

• OSTI ID: 20640326
• Journal Information: Physical Review. A, Journal Name: Physical Review. A Journal Issue: 4 Vol. 68; ISSN 1050-2947; ISSN PLRAAN
• Country of Publication: United States
• Language: English

Related Subjects

74 ATOMIC AND MOLECULAR PHYSICS
ATOMS
CADMIUM
COMPARATIVE EVALUATIONS
CORRECTIONS
DIFFRACTION
DISTURBANCES
DYE LASERS
ELECTRON CORRELATION
ELECTRONS
EXCITATION
FLUORESCENCE
FLUORESCENCE SPECTROSCOPY
GROUND STATES
ISOTOPE EFFECTS
L-S COUPLING
LASER RADIATION
MOLECULES
PERTURBATION THEORY
POTENTIAL ENERGY
POTENTIALS
RELATIVISTIC RANGE
SELF-CONSISTENT FIELD
ULTRAVIOLET SPECTRA
VALENCE
VAN DER WAALS FORCES
VIBRATIONAL STATES