Alkali optical spectra

An instance of this type is found in the spectrum of Li I, as shown in fig. 4.4 note in particular how the df/dE curve for Li is distorted from the expected shape by the minimum below threshold, so that the curve rises rather than falls towards the threshold. The effect is not a perturbation alkali spectra have double excitations and inner-shell spectra very far in energy from the optical spectrum, so there are no intruders in this range. 

The F-center is the most fundamental color center defect in the alkali halide lattice. Although it is not laser-active, the optical properties of the F-center are important in understanding the laser physics of other color center lasers. The fundamental absorption band of the F-center, called the F band, corresponds to a transition fi om the Is-like ground state to the 2p-like first excited state of the square-well potential. The F-band transition is very strong, and dominates the optical spectrum of the alkali-halide crystal. In fact, the term F-center comes fi om the German word Farbe, meaning color, and refers to the strong color imparted to the otherwise transparent alkali-halide crystals. 

In the pressure interval studied, (147-980) 10 newton m", the flame spectrum of NG powder and RDX was continuous except for several lines of the alkali metals. This permitted determination of temperature by optical methods... 

Methods. All solutions were prepared to be ImM Cytochrome c, 0.1mM DCIP, 0.10M alkali halide, and 0.10M phosphate buffer at pH 7.0 or pD 7.0. The DCIP served as a mediator-titrant for coupling the Cytochrome c with the electrode potential. E° values were measured using a previously described spectropotentiostatic technique using an optically transparent thin-layer electrode (OTTLE) (7,11,12). This method involved incrementally converting the cytochrome from its fully oxidized to fully reduced state by a series of applied potentials. For each potential a spectrum was recorded after equilibrium was attained. The formal redox potential was obtained from a Nernst plot. The n value... 

By measurement of the wave length of the residual rays, for instance with a diffraction grating, it is possible to get a direct measurement of the maximum frequency in the optical band of the vibration spectrum of an alkali halide. If we treat the spectrum by the Debye method, regarding... 

The method used to observe the infrared spectra of the deposits is relatively simple. The optics of a single-beam infrared spectrometer have been modified so that light from the Nernst filament is incident nearly normally on the drum and the light that is reflected directly from the surface of the drum is focused on the slit of the spectrometer. Because of the nature of the optics and the detector it is not feasible to divide the deposit into two bands as for the ultraviolet and visible spectra. Thus a blank run in which no alkali metal is deposited has to be made to provide a reference spectrum. 

The radical anion of molecular oxygen (O ) has been prepared and trapped in a range of alcohols, water and benzene but not in aliphatic hydrocarbons (Bennett et al., 1968a). In contrast to COg the e.s.r. spectrum shows that 0 interacts strongly with its immediate environment. This interaction which alters the separation of the upper molecular orbitals of the anion is strongly dependent on the nature of the matrix. Previously, the Oj" radical ion has been stabilized only in ionic materials such as the alkali halides thus it is of particular interest to find that this anion can be trapped successfully in a non-polar matrix (benzene). There is some evidence (Evans, 1961), from optical spectroscopic studies that molecular oxygen can form a weak charge transfer complex with the 77-electron system in benzene and it seems probable that O2 is stabilized in benzene by the formation of a similar complex. 

The electrons ejected from molecules by the passage of ionizing radiation through condensed media can be solvated very soon after the primary ionizing event and the solvated electron, e q, so formed can undergo chemical reactions with solute and solvent molecules. The main evidence for the existence of solvated electrons in the liquid phase has been obtained by the use of pulse radiolysis in conjunction with optical spectroscopy (Hart and Boag, 1962). Very recently the e.s.r. spectrum of the solvated electron has been obtained by a similar method (Avery et ah, 1968). The solvated electron is not located on one solvent molecule but is associated with an assembly of molecules which form a potential well around the electron by virtue of dipolar and polarization forces. There is a close similarity between this system and the blue solutions obtained by dissolving alkali metals in liquid ammonia. 

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