Contents 1 Electronic Absorption Spectrum

D. J. Tannor Prof. Rabitz, from the time-domain formulation of conventional electronic absorption spectroscopy, we know that the information content in the wavepacket autocorrelation function is identical to that in the high-resolution spectrum. Yet it is clear that the wavepacket autocorrelation function only directly probes the times at... 

In the presence of soft-core micelles at high water content (Wo = 60), the absorption spectrum consists of a broad band with a maximum around 710 nm. To explain the blue-shift and the broadening of the hydrated electron absorption spectra, the effect of sodium perchlorate in aqueous solution was studied. Without any additive, the absorption spectrum of the hydrated electrons was centered at 720 nm, and on adding 5M sodium perchlorate to the water solution, a blue-shift of the absorption spectrum was observed with a maximum centered at 650 nm. The blue-shift observed in the reverse micelles at low Wo is due to the high concentration of sodium ions (and ion-pairs) in the micellar core, at Wo = 5 and [Na] = 10 M of the sodium sulfonate (Pileni et al., 1982). 

Thomas and co-workers found that high-energy y-radiation will ionize the zeolite framework, forming holes and electrons [131]. In the presence of intrazeolitic water, hydrated electrons (H20) were formed, and characterized by their electronic spectra and short lifetimes. Figure 15a shows the transient absorption spectrum (20 ns) of the hydrated electron as a function of water content in zeolite X. For the zeolite with 41 water molecules per pseudo cell, the band at 600 nm was assigned to the hydrated electron. Upon decreasing the water content to 31 molecules per... 

For high-temperature chars whose carbon content exceeds 92%, a broad absorption begins to dominate the spectrum. This effect is similar to that observed in high-rank coals (above 92% C), which has been attributed to electronic absorption (9, 10). 

After a definite delay, the duration of which is determined by the setting of the electronic delay unit, the much weaker spectroscopic flash tube is fired. The almost continuous radiation from this source passes through the reaction mixture, the absorption spectrum of which may be recorded photographically in the spectrograph. Experiments with different delay times, but identical reaction mixtures, give information about the variation with time of the contents of the reaction cell (reactants, products and intermediates). One obvious modification to the technique... 

Contents Theory of Electrons in Polar Fluids. Metal-Ammonia Solutions The Dilute Region. Metal Solutions in Amines and Ethers. Ultrafast Optical Processes. Metal-Ammonia Solutions Transition Range. The Electronic Structures of Disordered Materials. Concentrated M-NH3 Solutions A Review. Strange Magnetic Behavior and Phase Relations of Metal-Ammonia Compounds. Metallic Vapors. Mobility Studies of Excess Electrons in Nonpolar Hydrocarbons. Optical Absorption Spectrum of the Solvated Electron in Ethers and Binary Liquid Systems. Subject Index. Color Plates. 

Fullerene-styrene copolymers have been prepared in radical initiated and thermal polymerization reactions [148-151]. In radical copolymerizations of Cgg and styrene, copolymers with Cgg contents up to 50% (wt/wt) can be obtained [150]. Electronic absorption spectra of the copolymers are very different from that of monomeric C o (Fig. 36). The absorptivities per unit weight concentration of the copolymers j increase with increasing C q contents in the copolymers in a nearly linear relationship (Fig. 37). Fluorescence spectra of the Cgg-styrene copolymers, blue-shifted from the spectrum of monomeric Cgo, are dependent on excitation wavelengths in a systematic fashion [149]. Interestingly, the observed absorption and fluorescence spectral profiles of CgQ-styrene and Cyg-styrene copolymers are very similar, even though the spectra of monomeric CgQ and C70 are very different. The absorption and fluorescence spectra of the fullerene-styrene copolymers are also similar to those of the pendant Cgg-poly-styrene polymer (19) prepared in a Friedel-Crafts type reaction [150,156]. 

Actually, the IR absorption features depend on the chemical short-range order of the lattice, and their appearance is only a necessary (not a sufficient) condition for the existence of the respective phases. There exist some more BN phases with either sp or sp short-range order which show essentially the same IR absorption as hBN and cBN, respectively. However, if used in combination with more direct methods such as electron diffraction, IR absorption is a fast and reliable method for determination of the phase content of BN thin films and has found widespread application. In Fig. 4 the IR absorption spectrum of a BN film is given as an example which shows a distinct absorption near 1050 cm and only weak absorption at about... 

The 2,6-xylenol content is determined using the second derivative - difference absorption spectrum of its phenolate as the peak amplitude, D2, at wavelengths of 302.0 -312.5 nm. The calibration constant, K.2 = D2/C2, was found to be 5.71 x 10 mg dm (SD = 0.07 X 10" mg dm ) calculated from six measurements). The positions of the maxima on the second derivative curves are influenced by the mode of derivation (electronic, microcomputer) and by the setting of the spectrophotometer controls. 

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