Emission spectra of calcium dimer. The A u -X l Xg system (original) (raw)
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Observation of the ... system of calcium dimer
We report the observation of collision-induced spectra of calcium dimer in the 680-692 nm region, The spectra were recorded after resonant laser excitation of 4 s4 P 3 PI state of atomic calcium. Here the upper state a 3 L:~ is populated through collisions, The same spectra were reproduced in a low-current glow discharge in calcium vapor. The assignment of the observed spectral lines was carried out by applying the Dunham-type analysis and the spectra were assigned to the a 3L:~-X I L:; transition of Caz, The existence of a 3L:~ state with voo = 13850 ± 1 cm-I and We ~ 37,6 cm-I is confirmed,
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.
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.
AIP Conference Proceedings, 2011
We study the laser induced fluorescence spectroscopy of the calcium dimer deposited on helium and mixed helium/argon clusters. In the wavelength range between 365 and 385 nm, the Ca dimer is excited from its ground state up to two excited electronic states leading to its photodissociation in Ca(1 P)+Ca(1 S): this process is monitored by recording the Ca(1 P) fluorescence about 422.7 nm. These electronic excited states of Ca 2 are respectively a diexcited one correlating to the Ca(4s 4p 3 P) + Ca(4s 3d 3 D) and a repulsive one correlating diabatically to the Ca(4s 4p 1 P) +Ca(4s 2 1 S) asymptote, accounting for the dissociation of Ca 2 and the observation of the subsequent Ca(1 P) emission. On pure helium clusters, the fluorescence consists of the calcium atomic resonance line Ca (1 S ← 1 P) at 422.7 nm (23652 cm-1) assigned to ejected calcium, and a narrow red sided band corresponding to calcium that remains solvated on the helium cluster. Interestingly, the branching ratio to the ejection of Ca(1 P) increases along with the wavelength of the excitation photon, i.e. when its energy decreases. This is contrary to what is intuitively expected and to what is really found on pure argon clusters. On mixed helium/argon clusters, a new spectral band appears on the red side of the calcium resonance line; the intensity and the red shift of this component increase along with the argon quantity deposited on the helium cluster: it is assigned to the emission of Ca(1 P) associated with the small argon aggregate embedded inside the helium cluster.
Optogalvanic Spectra of Calcium in the 6090-6760 A Region
Optogalvanic spectra of some 30 transitions of calcium originating from the ground state as well as from several excited states (4s4p 1.3p, 4s3d 1,3D, 4s5p 3p, 3d4p 3D, 3F) have been investigated using laser-irradiation of a low-current glow discharge in a thermionic diode. The influence of various experimental parameters such as bias field, oven temperature and buffer gas pressure on the spectra are reported. Seven previously unreported transitions are recorded including four "forbidden" transitions which violate the J selection rules. An interesting anomaly observed in the non-statistical population of the 4s3d 3D multiplet is discussed where the populations 3,2,1 of 3D 3 : 3D 2 : 3D 1 are in the ratio of 94 : 5" 1. A possible explanation is based on avoided crossing between potential energy curves of the Ca-Ar molecule.
Reaction dynamics of electronically excited calcium atoms with carbon tetrachloride
Chemical Physics Letters, 1990
Absolute values of the total chemiluminescence cross-section for the beam gas Ca*('P, ID) tCl,C+CaCI(A, B) +ClaC reaction have been measured at low collision energy, E,=O. 15 eV. Both metastable calcium atomic states Ca('P, 'D) were produced by low voltage dc-discharge conditions. By changing the discharge conditions different metastable concentrations were produced to measure the state-to-state cross-section for both 'P and 'D reactions. The following values of the total chemiluminescence rcaction cross-sections for Ca*('P, 'D) +Cl&-CaCI*(A, B) +Cl,C were obtained: o,,,= 1.77 A* and crlp =0.25 A'.
The Journal of Chemical Physics, 1999
The excited Ca(4s4d␦ 3 D J)RG͓ 3 ⌬ 1,2 ͔ states (RGϭAr, Kr, Xe͒ have been characterized spectroscopically by R2PI ͑resonance-enhanced two-photon ionization͒ spectroscopy. The main vibrational progressions, assigned to Ca(4s4d␦ 3 D 1)RG͓ 3 ⌬ 1 ͔←Ca(4s4 p 3 P 0)•RG͓ 3 ⌸ 0 Ϫ ͔ transitions, have weak subbands 3.7Ϯ0.5 cm Ϫ1 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 3 D J) atomic contribution. This indicates that there is no ''heavy-atom'' mixing of RG(nd␦) character into the wave functions of the CaRG(3 ⌬) states.
Photoionization of ground and excited states of Ca+ and comparison along the isoelectronic sequence
Photoionization cross-section calculations are performed on the ground state ([Ne]3s 2 3p 6 4s 2 S e 1/2 ) and the first two excited states ([Ne]3s 2 3p 6 3d 2 D e 3/2 and [Ne]3s 2 3p 6 3d 2 D e 5/2 ) of Ca + ions for photon energies from threshold to 45.0 eV using the relativistic (Breit-Pauli) R-matrix method. The discrete Ca 2+ orbitals are generated using the computer program AUTOSTRUCTURE; 30 configurations are included in the configuration-interaction calculation for the states of Ca 2+ . The prominent 3p → 3d giant resonances are analyzed and identified, and our results are compared with experimental results, and rather good agreement is found. Using results of our previous photoionization calculations on Sc 2+ and Ti 3+ ions, the strongest and broadest resonances in the photoionization cross section of those three ions (Ca + , Sc 2+ , and Ti 3+ ), in terms of width and oscillator strengths, are compared to show the evolution as a function of nuclear charge.