Level scheme complete

In the case of dibenzene chromium and its cation, the most complete investigation of the electronic spectra is due to Yamada and co-workers (76) who report both solution and crystal spectra in detail for dibenzene chromium iodide and ditoluene chromium iodide. Four intense bands were observed in the region 3 to 6 eV, and a detailed discussion of these in terms of molecular-orbital assignments has been given by Berry (78), although no direct comparison with the energy-level scheme of Shustorovich and Dyatkina (75) is reported. The intense band at 5.51 eV (log max = 4.14) for... 

A strong anharmonie interaction between the vibrations approximately described as rXH and vX.ll Y. There is independent evidence for a parametric relationship between the X Y and X—H interim clear distances from diffraction studies. The resulting effect on the vibrational spectrum increases with the anharmonicity and amplitude of both types of vibration, and seems to be most completely described by a type of energy level scheme proposed by Stepanov. A slight extension of this theory proposed here enables it to explain the persistence of broad vX l absorption regions at low temperatures. 

Consider the excitation of a molecule with the energy-level scheme described. Let ifiE be an eigenfunction of the complete Hamiltonian, H, and zeroth order Hamiltonian, H0, corresponding to the single discrete state, the set of vibronic states of another electronic state, and the fragmentation continuum, respectively. We write,... 

Frohlich (1947) based his calculations on the hypothesis of the energy-level scheme shown in Fig. 6.1, where conduction electrons are derived from impurity levels lying deep (V = 1 eV or more) in the forbidden zone. There is also a set of shallow traps spread below the conduction-band edge (F> AF> kT). In outline, the theory of breakdown is then as follows. In an applied electric field E, energy is transferred directly to the conduction electrons (charge e, mass m) at a rate A = jE, where j is the current density. If we suppose that each electron is accelerated in the field direction for an average time 2r between collisions at which its energy is completely randomised, then the mean drift velocity of the conduction electrons in the field direction... 

Using the calculated energy level list the complete energy level scheme can be deduced as shown in Fig. 5.9. In this figure each energy level is labelled with a number in parenthesis, corresponding to the numbering used by NMR-SIM. Each transition is labelled with a number from 1 to 12 that correlates with a specific spectral line. Thus the... 

The first measurement of the temperature dependence of an optical line width in an actinide system, Np + in LaC, was recently completed (47). The fluorescence transitions at 671.4 and 677.2 nm were studied from 10 to 200 K. The low temperature limit for the line width of the 677.2 nm transition is 16.5 GHz and is a measure of the width of the first excited crystal-field level of the ground manifold. The 671.4 nm transition has a line width of 0.55 GHz at 10 K. Its temperature dependence is described in terms of an effective three-level scheme for the excited manifold. The parameters are comparable to those found for Pr + in LaF. Further comparison depends upon the details of the phonon spectrum and the electronic states. At low temperatures, the residual width of the 671.4 nm transition was limited by the laser line width. This is consistent with the very narrow line widths observed in Pr +. Additional detailed studies of this type and proper contrast and comparison between lanthanides and actinides may provide the additional information needed to describe the electron-phonon and electron-ligand interactions of the actinides. 

The three rotational constants completely determine the energy level scheme of a rigid asyrmnetric top. This scheme may be considerably more complex than that of a synunetric rotor, especially if n is close to zero. Like it has already been shown for hnear and synunetric-top molecules, the number of parameters required to theoretically reproduce accmately measured rotational spectra may increase considerably if effects of rotation-vibration interaction, spin coupling, or internal rotation must be taken into account. Details of practical importance will be considered below. 

Nuclear level schemes and resonance parameters are of great interest for nuelear spectroseopy, for astrophysical models, thermonuelear ealeulations and for other applieations. Parameters for nuelear levels of stable nuclei have been published in the Volumes I/16B, I/18A, B, C, andinI/19Al, A2. In the Volumes I/19A, B further data obtained from transfer reaetions are presented. Volume I/19C eontains the data of unstable nuclei far from the stability region whieh have been dedueed from reactions oflier than transfer reactions (e.g. beta deeay, spallation reactions, or inverse reactions). The data in these volumes should be considered as the most complete data collection for nuclear levels. 

Although transit-time broadening is greatly reduced by the Ramsey technique, the quadratic Doppler effect is still present and may prevent the complete resolution of the recoil components. This may cause asymmetric line profiles where the central frequency cannot be determined with the desired accuracy. As was shown by Helmcke et al. [1269, 1277], one of the recoil components can be eliminated if the upper level Pi of the Ca transition is depopulated by optical pumping with a second laser. In Fig. 9.63 the relevant level scheme, the experimental setup, and the measured central Ramsey maximum of the remaining recoil component are shown. 

For a theoretical explanation of the signal we consider a simplified level scheme with four sublevels in the ground and four in the excited state (see Fig. 1). This corresponds to an atomic system with angular momentum J = Y and a nuclear spin I =. A complete treatment of the Cs case would require to calculate with 32 sublevels in minimum. However, we can expect that the reduced level system already includes the essential coherence phenomena and in principle shows the same structure only with slightly modified amplitudes for the oscillations. 

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