Second spectra

II, second spectra from singly ionized atoms, and so on for successive stages of ionization. 

The first and second spectra of plutonium are probably the most thoroughly studied of any in the periodic table insofar as experimental description of the observed spectra and the term analysis is concerned, but a detailed quantum mechanical treatment has been handicapped by their great complexity. Fortunately, the lowest odd and lowest even configurations for both Pu I and Pu II are relatively simple, and parametric studies of the lowest levels of the 5f67s2, 5f56d7s2 and... 

The example is typical for many applications of Mossbauer spectroscopy in catalysis a catalyst undergoes a certain treatment, then its Mossbauer spectrum is measured in situ at room temperature. Flowever, if the catalyst contains highly dispersed particles, the measurement of spectra at cryogenic temperatures becomes advantageous as the recoil-free fraction of surface atoms increases substantially at temperatures below 300 K. Secondly, spectra of small particles that behave superparamagne-... 

In (g). We have estimated the heat of sublimation. The values for the energy states of gaseous monatomic indium are from the following first spectra, Paschen and Meissner,1 Uhler and Tanch1 second spectra, Lang and Sawyer1 third spectra, Rao, Narayan, and Nao.1 See also Bacher and Goudsmit.1... 

Two philosophies have been developed for the fast registration of X-ray absorption spectra [73-76]. One of these can be characterized as a brute-force variant of the normal transmission experiment, where the energy of the primary beam is increased stepwise. It takes about 20-30 min to take a full spectrum, and much of this time is used to perform corrections in the adjustment of the beam and to calm down mechanical vibrations and instabilities, which occur after every movement of the monochromator crystal. The QEXAFS (Quick-Scanning EXAFS) method [75,76] uses a step-wise, rather than a continuous motion of the motors driving the movement of the crystals, so that such extra times are not necessary. If the counting times of the detectors are minimized as well, a full XAFS spectrum of sufficient quahty can be obtained in a few seconds. Spectra with only minor losses in quahty as compared to conventional step-by-step scanning can be obtained in a few minutes. 

Racah began his discussion of the second spectra by regretting that the absence of relevant data precluded the construction of formulas of the type represented by eqs. (80)-(82). Instead, he suggested that it might be useful (and much more convenient) to compare differences in energy between the lowest levels of opposite parity (the so-called system differences) in the second and third spectra. He noted, for example, that we can write... 

Contrary to the situation in the first and second spectra, where the lowest configurations of the A and B systems compete for the title ground configuration, the configuration 4f ( low B ) in the third spectra is lower than 4f (5d + 6s) ( low A ) by such an amount that most of the transitions between... 

In the first and second spectra complete new lists of energy levels are needed in this way, the understanding obtained till now of relatively simple spectra at both ends and in the middle of the group can be used for interpreting the still remaining complex spectra. 

Survey IH spectra were run for product identification using a sweep width of 8000 Hz (20 ppm), a pulse width of at least 12 microseconds (30 degrees), an acquisition time of 2-4 seconds and a pulse delay of 2-4 seconds. Corresponding 13C spectra were acquired using a sweep width of at least 25000 Hz (250 ppm), an acquisition time of 1.6 seconds, and a pulse delay of 2-3 seconds. Spectra were accumulated until the desired signal-to-noise ratio was achieved. Pre-saturation of the large H2O peak was often used (standard Varian software) to minimize this resonance in the spectrum. 

Fig. 4. Proton magnetic resonance spectral assignments for A batrachotoxinin A, B batrachotoxin, and C homobatrachotoxin. Chemical shifts in ppm for deuterochloroform with a tetramethylsilane standard s singlet d doublet t triplet q quartet br broad. Coupling constants are in parentheses in cycles per second. Spectra (100 MHz) are depicted by Tokuyama et al. (251) and in Fig. 5. Capital letters A—M refer to assignments in Fig. 5. Values for batrachotoxinin A differ somewhat from those reported later for synthetic and natural compound by Imhof et al. (144,145). It appears likely that the values of Imhof et al. correspond to the free base and that the earlier values of Tokuyama et al. were for mixtures of free base and cationic form present in the CDCI3. Certain earlier assignments (257) have been revised in light of the detailed examination of the spectrum of batrachotoxinin A by Imhof etal. (145)...

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