Oscillator strength atomic

B2.2.5.5 ATOMIC FORM FACTOR AND GENERALIZED OSCILLATOR STRENGTH... 

Fig. 6. Optical spectrum of Ir atoms isolated in solid Ar at 10-12 K, compared to the gas-phase atomic transitions of Ir. The stick heights correspond to reported oscillator strengths of gaseous Ir atoms (49).

Here Z is the charge of the projectile with velocity v. In order to calculate stopping powers for atomic and molecular targets with reliability, however, one must choose a one-electron basis set appropriate for calculation of the generalized oscillator strength distribution (GOSD). The development of reasonable criteria for the choice of a reliable basis for such calculations is the concern of this paper. 

CEX (ionization potential) = 13.6 eV, Yn = 6.08 eV f°r N atom of indoline ring is used in PPP calculation. The carbon for indoline component is ignored for PPP calculation. Other parameters listed in Ref. 15. Oscillator strength. 

Bloch (1933a,b) first pointed out that in the Thomas-Fermi-Dirac statistical model the spectral distribution of atomic oscillator strength has the same shape for all atoms if the transition energy is scaled by Z. Therefore, in this model, I< Z Bloch estimated the constant of proportionality approximately as 10-15 eV. Another calculation using the Thomas-Fermi-Dirac model gives I tZ = a + bZ-2/3 with a = 9.2 and b = 4.5 as best adjusted values (Turner, 1964). This expression agrees rather well with experiments. Figure 2.3 shows the variation of IIZ vs. Z. 

The literature on transition probabilities (or oscillator strengths) is vast, rapidly growing and difficult to summarize. A small selection for atoms and molecules is given in Allen, AQ and larger selections in... 

The best theoretical data for oscillator strengths and other atomic properties are becoming available from the Stellar Opacity Project (Seaton 1987 Seaton... 

In general, only atoms in the flame that are the same as in the hollow cathode material can absorb the specific lines emitted by this material. The only requirement of the monochromator, then, is to isolate the desired line from other lines of the cathode material and the lines of the filler gas. One line of the element is usually absorbed more strongly than others (it has a higher oscillator strength ). This often, but not necessarily, corresponds to the electronic transition from the ground state to the lowest excited state. This line is selected for maximum sensitivity measurements. For high concentrations, a line with a lower oscillator strength may be selected. 

Notes Oscillator strengths are given within parentheses. Q(Re) gives the Mulliken charge on one Re atom. 

N = Total number of atoms which can absorb at v, and /= Ability for each atom to absorb at v (oscillator strength). 

The corresponding quantum mechanical expression of s op in Equation (4.19) is similar except for the quantity Nj, which is replaced by Nfj. However, the physical meaning of some terms are quite different coj represents the frequency corresponding to a transition between two electronic states of the atom separated by an energy Ticoj, and fj is a dimensionless quantity (called the oscillator strength and formally defined in the next chapter, in Section 5.3) related to the quantum probability for this transition, satisfying Jfj fj = l- At this point, it is important to mention that the multiple resonant frequencies coj could be related to multiple valence band to conduction band singularities (transitions), or to transitions due to optical centers. This model does not differentiate between these possible processes it only relates the multiple resonances to different resonance frequencies. 

The very weak Tm - So transitions are hard to observe directly by absorption spectroscopy. Even with long cells, the high concentrations required present solubility — and what is more important — purity problems. An impurity of 1 10 may give rise to absorption bands which have the same intensity as the expected Ti So absorption. The experimental conditions, therefore, have to be chosen to allow an increase of the Ti- - So oscillator strength to be achieved through perturbation by paramagnetic species (O2 or NO) or heavy atoms. Alternatively, an indirect method, phosphorescence excitation spectroscopy, which has high sensitivity and selectivity, may be applied. 

Instead of one resonance frequency per individual electron, Bethe recovered the spectrum of resonance frequencies for the atom, weighted by dipole oscillator strengths satisfying the sum rule... 

Relativistic Oscillator Strengths for Excited-State Transitions in Halogen Atoms. Regularities... 

Relativistic Quantum Defect Orbital (RQDO) calculations, with and without explicit account for core-valence correlation, have been performed on several electronic transitions in halogen atoms, for which transition probability data are particularly scarce. For the atomic species iodine, we supply the only available oscillator strengths at the moment. In our calculations of /-values we have followed either the LS or I coupling schemes. 

Spectral lines are often characterized by their wavelength and intensity. The line intensity is a source-dependent quantity, but it is related to an atomic constant, the transition probability or oscillator strength. Transition probabilities are known much less accurately than wavelengths. This imbalance is mainly due to the complexity of both theoretical and experimental approaches to determine transition probability data. Detailed descriptions of the spectra of the halogens have been made by Radziemski and Kaufman [5] for Cl I, by Tech [3] for BrIwA by Minnhagen [6] for II. However, the existing data on /-values for those atomic systems are extremely sparse. 

In Tables -A, we report oscillator strengths for some fine structure transitions in neutral fluorine, chlorine, bromine and iodine, respectively. Two sets of RQDO/-values are shown, those computed with the standard dipole length operator g(r) = r, and those where core-valence correlation has been explicitly introduced, Eq. (10). As comparative data, we have included in the tables /-values taken from critical compilations [15,18], results of length and velocity /-values by Ojha and Hibbert [17], who used large configuration expansions in the atomic structure code CIVS, and absolute transition probabilities measured through a gas-driven shock tube by Bengtson et al. converted... 

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