Experimental study of the Ca2 1S+1S asymptote (original) (raw)
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European Physical Journal D, 2003
The van der Waals coefficients C6, C8 and C10 at the 1 S+ 1 S calcium dimer asymptote are determined from spectroscopic observations. The filtered laser excitation technique was applied for measuring transition frequencies of the Ca2 B-X system from asymptotic levels of the X 1 Σ + g ground state reaching v = 38. That level which is only 0.2 cm −1 below the molecular 1 S+ 1 S asymptote has an outer classical turning point of about 20Å. The extraction of confidence limits for the long range coefficients including the dissociation energy from the experimental data involving Monte Carlo simulation is described. A range for the s-wave scattering length is derived.
Study of coupled states for the (4s 2 ) 1 S + (4s4p) 3 P asymptote of Ca2
European Physical Journal D, 2005
The coupled states A1Σu+ (1D + 1S), c3Πu (3P + 1S) and a3Σu+ (3P + 1S) of the calcium dimer are investigated in a laser induced fluorescence experiment combined with high-resolution Fourier-transform spectroscopy. A coupled state analysis of the observed levels, considering a potential model, which is complete within the subspace of relevant neighboring states, is performed using the Fourier Grid Hamiltonian method. We determine the potential energy curve of the A1Σu+ and c3Πu states and the strengths of the couplings between them. The c3Πu and a3Σu+ states are of particular importance for the description of collisional processes between calcium atoms in the ground state 1S0 and excited state 3P1 applied in studies for establishing an optical frequency standard with Ca.
The Journal of Chemical Physics, 1999
The weakly bound Ca(4s4d 3 D 3)•Ar͓ 3 ⌺ ϩ ͔ state has been characterized by means of R2PI ͑Resonant Two-Photon Ionization͒ spectroscopy, using transitions from the Ca(4s4 p 3 P 0) •Ar͓ 3 ⌸ 0 Ϫ͔ metastable state prepared in a laser-vaporization/supersonic jet source. Because several of the vibrational levels are above the dissociation limit ͓to Ca(4s4d 3 D 3)ϩAr(1 S 0)], it is concluded that there must be a substantial maximum in the Ca(4s4d 3 D 3)•Ar͓ 3 ⌺ ϩ ͔ potential curve ͑Ͼ200 cm Ϫ1 ͒ at large R ͑Ͼ4.0 Å͒. This is discussed, and shown to be consistent with our earlier ideas of ''penetration'' of outerlobes of electron density of metal atom excited states by RG ͑rare-gas͒ atoms. Perturbations observed, due to possible potential curve crossings with states of different electronic symmetry, are also discussed.
Spectroscopic characterization of excited Ca
2017
The excited Ca(4s4d DJ)RG 3 1,2 states (RG Ar, Kr, Xe have been characterized spectroscopically by R2PI resonance-enhanced two-photon ionization spectroscopy. The main vibrational progressions, assigned to Ca(4s4d D1)RG 3 1 ←Ca(4s4p 3P0)•RG 3 0 transitions, have weak subbands 3.7 0.5 cm 1 to the blue which have been assigned to analogous transitions to the 3 2 upper states. For CaAr and CaKr, rotational analysis has confirmed this assignment. The 3 2 /3 1 splitting is within experimental error the value expected if the molecular spin-orbit coupling constant is derived entirely from the Ca(4s4d DJ) atomic contribution. This indicates that there is no ‘‘heavy-atom’’ mixing of RG(nd ) character into the wave functions of the CaRG(3 ) states. © 1999 American Institute of Physics. S0021-9606 99 01526-3
Theoretical study of the atomic spectra of the calcium atom
Chemical Physics Letters, 1992
Theoretical calculations are reported for the following terms of the atomic spectra of the Ca atom: ~ S (4s 2 ), l p (4s4p), 3p (4s4p), ~D(4s3d), 3D(4s3d), ~P(4s5p), 3p(4s5p). The method is based on all-electron calculations at the Hartree-Fock level followed by a configuration interaction for the two valence electrons. Core-valence (or intershell) correlation effects are introduced via a second-order perturbation development or via a core-polarization potential. The agreement with the experimental spectra is very good.
Emission spectra of calcium dimer. The A u -X l Xg system
The AIX~+-X 1 + Xg spectral system of Ca 2 has been studied in two independent experiments. The collision-induced fluorescence due to this band was investigated following the resonant excitation of the 4s4p 3P 1 metastable state of calcium using a Nd : YAG laser pumped dye laser. In another experiment, a low current glow discharge in calcium vapor was used. We have assigned 86 spectral lines to this band system for vibrational quantum numbers (v'= 10-13 and v"= 0) by A X u state dissociation energy D~ is estimated to be ~ 8693.6 + 1 cm-1. The applying a Dunham type analysis. The 1 + processes involved in the collisional excitation of the upper molecular state are discussed.
Energy Levels and Oscillator Strengths of Ca V
2021
We report an extensive and elaborate theoretical study of excitation energies and radiative data for the lowest 148 fine-structure levels of Sulphur-like Ca using Configuration Interaction Method (CIV3). We have included the relativistic effects using Breit-Pauli approximation by adding mass-correction, Darwin and Spin-Orbit terms to the non-relativistic Hamiltonian. Dipole allowed transitions are fined tuned by adjusting diagonal elements of the Hamiltonian Matrix.The exact identification of many levels becomes tedious due to the strong mixing between several fine-structure levels. We have compared our calculated values of energywith the data compiled by National Institute of standard and Technology (NIST) and found good agreement. We have reported data for many new levels which are not in the NIST database.
Laser gain is reported on the 4p3d 3F -4s3d 3D transitions of Ca at 643.907, 646.257, 647.166, and 649.378 nm following optical pumping of the 4s2 'So -4s4p 3PI intercombination transition at 657.278 nm. The effect is realized through large scale collisional redistribution of energy which rapidly leads to the excitation of higher states and eventual ionization of Ca atoms. Our calculations based on a simple rate equation model suggest that population inversions are a combined result of direct excitation of the upper lasing states through inelastic collisions, and three-body recombination.
The first two excited 1g+ states of Cs2
Chemical Physics Letters, 1984
fluoresccncc of Cs2 molecules in the infrared region (4000-9000 cm-') has been observed using scvcral cnciting wavelengths from an argon-ion laser and from a ring dye laser. Accuntc molecular constants for the fit two cscited tZi electronic states arc derived from spectra rccordcd at high resolution by Fourier transform spccrroscopy. hlain molecular constants are: (2)'2;: Tc = 12114.090 cm-*, we= 23.350 cm-'. 8, = 7.45 X 10m3 cm-'. R, = 5.8316 A; i3)'$: T,= 15975.450 cm-!, we = 22.423 cm-'. Be = 8.23 X 10W3 cm-'. R, = 5.5569 A.