The optical absorption spectra of solvated electrons in H20 and D20 have been measured at 274, 298, 340, and 380 K. All the spectra were fitted very well with the Gaussian and Lorentzian shape functions at the lowand high-energy sides of the absorption maximum, respectively, excluding the high-energy tail. The spectrum does not shift uniformly with temperature. The temperature coefficient of absorption decreases rapidly with increasing energy on the low-energy side of the absorption maximum, while it changes only slightly on the high-energy side. When the temperature increases the Lorentzian width remains constant, the Gaussian width varies proportionally to T1/2, and the spectrum becomes more symmetrical. On going from H20 to D20 we found that the spectrum at a given A/Amax shows a shift of +0.05 eV in the low-energy wing. The shift decreases with increasing energy, reaching 0.03 eV at the absorption maximum. On the high-energy side of the band the shift becomes negative at hv > 2.2 eV. The shift on the low-energy side seems to be related to the difference of the zero-point energies of the interand intramolecular vibrations. The wavelength dependence of the temperature and isotope effects is consistent with the model that different types of excitation occur on the lowand high-energy sides of the absorption band. The temperature and isotopic dependence of the low-energy side are consistent with its width being due to phonon interactions.

The width of the band at half-height, W\¡2, was divided into two portions, Wr and Wb, representing the parts on the red and blue sides of the absorption maximum EAmax. The average energy on the low-energy side of the band, represented by (EAmax -W,), is nearly the same in water (1.36 eV at 1 bar) as in the alcohols (1.34-1.49 eV at 1 bar). By contrast the average energy on the high-energy side of the band, represented by (EAmax + Wb), is ~0.7 eV higher in alcohols (2.8-3.0 eV at 1 bar) than in water (2.2 eV at 1 bar). The results are consistent with the following model. The low-energy side of the band represents the transition between the ground state and the first excited state, both of which are determined mainly by the potential well created by the OH groups. In alcohols the higher excited states are greatly affected by the (more weakly scattering) alkyl groups. The model is qualitatively similar to that of Delahay, but we find that the overlapping Gaussian shaped lines are not all of the same width and that the high-energy tail does not have the form (A/Amax) « £~8/3, but varies from one type of liquid to another. The relative increase in EAmax with pressure is greater in the alcohols than in water; it correlates with the relative increase in liquid density rather than with that in dielectric constant. The smaller change in EAmax in water is balanced by a relatively larger increase in the width parameters. Oscillator strengths estimated from the present more complete spectra have similar values in the alcohols (0.69-0.75) and water (0.76).

The effects of pressures up to 4 kbar on the density, dielectric constant, and viscosity of n-pentane, trl-iexane, n-octane, cyclopentane, methylcyclohexane, and 2,2-dimethylbutane (DMB) were measured at 30 "C. The pressure effects on the viscosities of n-hexane and n-octane were also determined at 0 and 60". The densities of diethyl ether and cyclopentanone and the dielectric constant of carbon tetrachloride at high pressures are a!so recorded. The densities of the hydrocarbons increased by 20-30% and the dielectric constants increased by 11-16 % as the pressure was increased from 1 to 4000 bars at 305, but the viscosities increased by 695-2352 % over the same pressure range. Carbon tetrachloride froze at 1500 bars at 30°, and cyclopentanone froze at 3500 bars at about 20'. In agreement with earlier work on other liquids, the value of the Clausius-Mosotti function (E -1) V/(E f 2) for the present compounds decreased slightly with increasing pressure. The viscosity at a given pressure decreased slightly with increasing temperature, and temperature effect increased with increasing pressure. In general, the slnaller the compressibility of the liquid, the greater was the effect of pressure on the viscosity; DMB was a n exception because its viscosity increased abnormally rapidly with pressure. Molecular structure and liquid structure have greater influences on the pressure dependence of viscosity than on that of density or dielectric constant.

The optical absorption spectra of solvated electrons in water, alcohols, and tetrahydrofuran are empirically resolved into two Gaussian bands and a continuun~ tail. The first Gaussian band covers most of the low energy side of the spectrum. The second Gaussian band lies at an energy slightly above that of the absorption maximum of the total spectrum. With the exception of teit-butyl alcohol, in water and alcohols the following were obserbed: ( 0 ) the first Gaussian bands have the same half-width, but the oscillator strength in water is about double that in an alcohol; (b) the second Gaussian bands have similar half-widths and oscillator strengths; (c) the continuum tails have similar half-midths, yet that in water possesses only about one third as much oscillator strength as one in an alcohol. 711 tert-butyl alcohol and tetrahydrofuran the first Gaussian band and the continuum tail each carry nearly half of the total oscillator strength. Chem. 57.591 (1979) Les spectres d'absorbtion optique des electrons solvates dams l ' e a~~, les alcools et le tetrahydrofuranne peuvent @tre resolus en~piriquement en deux courbes gaussiennes et en Line queue continue. La premiere courbe gaussienne recouvre presque toute la partie de faible energie du spectre. La deuxien~e courbe gaussienne se trouve a une energie Iegerement superieure au maxiillurn d'absorbtion du spectre global. A I'exception du teii-butanol, on observe generalement avec I'eau et les alcools, les faits suivants: (cr) les largeurs a demi-hauteur des premieres courbes gaussiennes sont approximativernent les rnsmes; la force de I'oscillateur dans I'eau est approximativement deux fois celle dans l'alcool: ( b ) les largeurs a demi-hauteur et les forces des oscillateurs des deuxiemes courbes gaussiennes sont semblables; (c) les largeurs a demi-qauteur des queues continues sont semblables; toutefois la force de l'oscillateur de celle de I'eau est environ trois fois rnoindre que celle d'un alcool. Dans le reri-butanol el le tetrahydrofuranne la force de I'oscillateur de la premiere courbe gaussienne est approximativement igal a cela de la queue continue. FANG-YVAN[Traduit par le journal] Introduction the \.lings OF the spectrum. Therefore. we have

A review is first given of presently available techniques for generating and observing long-lived dianions of molecules and of clusters in the gas phase. Multiply charged anions that have been unambiguously observed are listed with the technique used to detect them. The remainder of the article is then devoted to the way quantum chemistry can contribute to the continuing search for multiply charged negative ions. This discussion is divided into two parts: (i) ions in zero magnetic fields and (ii) ions in intense magnetic fields. In (i) it is difficult to bind even two electrons to a heavy neutral atom. In (ii), however, a heavy atom with atomic number Z can bind an additional Z electrons, the binding energy of these additional electrons being on the same order as that of the first Z electrons, in the so-called "hyperstrong" field regime. Diatomic homonuclear molecules have binding energies on the order of the separated atom energies. As there should be precursor effects, it is proposed that one should attempt multiply-charged anion formation in the highest available magnetic fields in the laboratory.