Absorption Spectrum Of Solvated Electron Research Articles

Optical absorption spectra of solvated electrons in mixtures of ammonia and methylamine

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTOptical absorption spectra of solvated electrons in mixtures of ammonia and methylamineCatherine M. Stupak, T. R. Tuttle Jr., and Sidney GoldenCite this: J. Phys. Chem. 1984, 88, 17, 3804–3810Publication Date (Print):August 1, 1984Publication History Published online1 May 2002Published inissue 1 August 1984https://doi.org/10.1021/j150661a024RIGHTS & PERMISSIONSArticle Views68Altmetric-Citations7LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (866 KB) Get e-Alerts

Energy Levels for Photoinjection of Excess Electrons into Ammonia Vapor at Various Densities — The Transition from the Quasi‐Free to the Localized Electron State

AbstractThe energy of the electronic levels in ammonia vapor which are populated by the photoinjection of excess electrons has been determined in the density range from 1.7 · 1017 to 2.3 . 1021 molecules/cm3 at T = 400 K. The method used is based on measuring the photoelectric work function of a stainless steel photocathode immersed in ammonia vapor with respect to that into vacuum. From these measurements the chemical potential of two bands of electron injection levels can be elucidated. These results are discussed together with electron mobilities which show with increasing vapor density a transition from the quasi‐free to the localized electron state. It will be shown that the onset of electron localization obeys Mott's criterion for quantum localization. From these results together with the optical absorption spectra of solvated electrons, and from theoretical considerations it follows that one of the injection bands is the conduction band. The other one is formed by pre‐existing solvent traps. Therefore, in contrast to the conventional assumption in the theory of photoemission, the electron injection into polar media does not occur only in the conduction band but also in pre‐existing trap states (band‐tail states) thus supporting Thompson's recent assertion. This requires the reinterpretation of existing data on photoemission of electrons into polar solvents (electrolytes) including the photoionization of solute molecules in polar solvents in order to determine the bottom of the conduction band V0.

Composition effects on optical absorption spectra of solvated electrons in alcohol/water mixed solvents

Addition of a few percent of water to an alcohol has a relatively large effect on the shape of the optical absorption spectrum of solvated electrons in the liquid. This occurs whether the optical absorption energy in the pure alcohol is greater or smaller than that in water. Addition of up to 10 mol% of water causes EAmax in methanol and primary alcohols to decrease, while it increases in secondary and tertiary alcohols. At around 10 mol% water in primary alcohols EAmax passes through a minimum and increases again at higher water concentrations, reaching a plateau at about 30 mol% and remaining constant up to about 95 mol% water; over the last part of the composition range to pure water EAmax decreases slightly. The behavior in secondary and tertiary alcohols containing > 30 mol% water is similar to that in primary alcohols. The width of the band at half height W1/2 is divided at EAmax into "red side" and "blue side" portions Wr, and Wb, respectively. In methanol and in primary and secondary alcohols, addition of up to 30 mol% of water greatly reduces Wb but has relatively little effect on Wr. At > 30 mol% water Wb and Wr are similar to those in pure water. In tertiary butyl alcohol the band width is similar to that in pure water, so addition of water to the alcohol makes little change in the band width. The water/alcohol composition effects on the es− absorption band parameters are attributed to changes in solvent structure. This is especially evidenced by the minimum in EAmax at 10 mol% water in a primary alcohol. The changes in band asymmetry Wb/Wr indicate that the types of electronic transition on the low and high energy sides of the band are different.

Thermal effects on solvated electron optical absorption bands in liquid ammonia and perdeuterioammonia

The shapes of optical absorption spectra of solvated electrons in liquids ammonia and perdeuterioammonia are shown to be the same within experimental error under nearly the same conditions, in the same solvent whether these spectra are obtained from spectra of metal solutions or from pulse radiolysis experiments. In addition, solvated electron absorption bands in each solvent at different temperatures display shape stability. As a result, most, if not all, of these absorption bands would appear to result from bound to continuum transitions.

Isotope and temperature effects on the optical absorption spectrum of solvated electrons in liquid ammonia

Substitution of D and H in ammonia increases the energy of the optical absorption maximum E/sub ..cap alpha../sub max// of solvated electrons by 0.04 eV at 200 to 240 K. The temperature dependence of E/sub ..cap alpha../sub max// may also be slightly larger in ND/sub 3/ (-2.6 MeV/K) than in NH/sub 3/ (-2.4 MeV/K). The bandwidth at half-height W/sub 1/2/ is unaltered by isotopic substitution. The low-energy side of the absorption band has a Gaussian shape. The width parameter of the Gaussian increased slightly with temperature, being g/sub 1/ = 0.010 T/sup 1/2/ eV in both NH/sub 3/ and ND/sub 3/. The high-energy side of the absorption band is neither a Lorentzian nor a single power function of E. If it is expressed by A/A/sub max/ varies as E/sup -..cap alpha../, the value of ..cap alpha.. decreases from 6 in the vicinity of A/A/sub max/ = 0.4 to 3 near A/A/sub max/ = 0.03. The band asymmetry parameter is W/sub b//W/sub r/ approximately equal to 1.35 at 200 to 240 K, similar to that for electrons in water at 300 K. The temperature coefficient -(delta E/delta T)/sub A/A/sub max// of the low-energy side of the band is greater than thatmore » of the high-energy side in ND/sub 3/ and water, and probably also in NH/sub 3/. The optical absorption transitions are different on the two sides of the band.« less

Width of the absorption spectrum of the solvated electron

A simple model for the absorption spectrum of solvated electrons is presented. A solvated electron is “an electron held in the center of the nuclei (this includes nuclei and their core electrons) of the solvating groups of the solvent plus the valence electron cloud of these groups”. The radius of “electron plus solvating nuclei” is fixed and is not affected by light absorption. However, the radius of “electron plus solvating nuclei plus valence electron cloud of the solvating nuclei” includes a variation equal to half the thickness of the valence electron cloud of the solvating groups, and this radius is increased by the absorption of light by the solvated electron. Based on this model, the bandwidth, W, at half-height of absorption maximum of the solvated electron fits the expression W = 0.19(8 n/ b 2)-0.33 for various solvents and various temperatures. In the above equation, W is in eV, n is an integer (number of the solvating groups per solvated electron, range 6–9), b (in Å) is a measure of the radius of “electron plus solvating nuclei plus valence electron cloud of the solvating nuclei” in the ground state of the solvated electron.

A vibronic problem of solvated electrons

An attempt is made to understand the relationship and the essential difference between the two alternative approaches to the absorption spectra of solvated electrons; the standard single-site models and the multiple-site (“electron-transfer”) formulation. Using two phenomenological models, it is shown that the spectral line widths predicted by the single-site models are necessarily narrower than those calculated by the electron transfer model, because of the restricted choice of the configuration coordinate in the former category. Such restriction arises from the assumption of the rigid medium potential for the excess electron and also from imposing the Born-Oppenheimer separability of electronic and nuclear wavefunction for the excited states which are extended over many solvent molecules, in the single-site models. The peak transition energies are nearly identical for the two approaches.

Temperature and isotope effects on the shape of the optical absorption spectrum of solvated electrons in water

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTTemperature and isotope effects on the shape of the optical absorption spectrum of solvated electrons in waterFang-Yuan. Jou and Gordon R. FreemanCite this: J. Phys. Chem. 1979, 83, 18, 2383–2387Publication Date (Print):September 1, 1979Publication History Published online1 May 2002Published inissue 1 September 1979https://doi.org/10.1021/j100481a016RIGHTS & PERMISSIONSArticle Views996Altmetric-Citations203LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (621 KB) Get e-Alerts

Band resolution of optical spectra of solvated electrons in water, alcohols, and tetrahydrofuran

The optical absorption spectra of solvated electrons in water, alcohols, and tetrahydrofuran are empirically resolved into two Gaussian bands and a continuum 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 tert-butyl alcohol, in water and alcohols the following were observed: (a) 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-widths, yet that in water possesses only about one third as much oscillator strength as one in an alcohol. In tert-butyl alcohol and tetrahydrofuran the first Gaussian band and the continuum tail each carry nearly half of the total oscillator strength.

Optical absorption spectra of solvated electrons in irradiated molten alkali halide mixtures

1. One optical absorption band of es− is observed in molten alkali halide mixtures, whose parameters have intermediate values between the values of the corresponding parameters of the es− absorption bands in melts of the individual components. 2. The energy of the optical transition is a nearly linear function of the molar composition of the mixture. 3. The obtained results serve as additional evidence that “solvated” electrons are formed in ionic liquids.

Small polaron model for the absorption spectrum of solvated electrons in alcohols

The absorption spectra of localized electrons in alcohol aggregates are studied in terms of the small-polaron model. The red and the visible spectra are ascribed to electrons in two different kinds of traps rather than to the “unrelaxed and relaxed” trapped electrons. The two trapping sites are hydrogen-bonded OH chains and the alkane part of the system. Each kind of trap is characterized by a finite activation energy for self-trapping, whose magnitude is related to the “stiffness”(or the frequency of the coupled normal mode) of the site. The OH chain has a higher frequency for the coupled vibrational mode than that of the alkane part, so that at 77 K electrons are initially trapped at the shallow alkane traps and then transferred to the deeper OH-chain traps. The proposed model is consistent with other experimental features: the effects of the size of the alkane part in normal alcohols and of the branched structure of the alkane part on the line-width and on the absorption peak of the visible spectrum, the chemical consequence of photo-bleaching the visible spectrum (i.e., production of H atoms), and the effect of scavengers on the growth of the visible spectra.

Influence of molecular structure on optical absorption spectra of solvated electrons in alcohols

Influence of molecular structure on optical absorption spectra of solvated electrons in alcohols

Resolution of the Absorption Spectrum of Solvated Electrons

The abosprtion spectrum of solvated electrons is resolved by superposition of one or several Gaussian-shaped bound-bound (bb) bands and one bound-continuum (bc) band. A previously derived equation is applied for the bc band. Energy levels, band amplitudes, widths, and contributions are given for tetrahydrofuran, ethylenediamine, hexamethylphosphoric triamide, water (all at room temperature), ammonia (−65°C), and 3-methylpentane (77°K). Resolution is tentative for ethylenediamine because of insufficient experimental data and for ammonia and water because of inadequancy of the equation for the bc band. Experimental evidence supports this equation for all solvents except ammonia and water. A theoretical limitation is indicated. Energy levels are correlated with the nature of the solvent as characterized by the difference β between the reciprocals of the optical and static dielectric constants. Spectra of solvated electrons in solvents with low β's show a major contribution from the bc transition and only one bb transition. Conversely, a high β results in a more complex spectrum with a relatively minor bc contribution.

Pulse radiolysis observations of solvated electrons in liquid hydrocarbons

The absorption spectra of solvated electrons in methylcyclohexane have been obtained at −113° C and 20° C and the decay kinetics observed. The homogeneous recombinations of electrons and cations in liquid methylcyclohexane and n-hexane at 20° C observed by pulse radiolysis occur with k = 8 × 10 13 and 2 × 10 14 M −1 sec −1 respectively. The reaction of electrons with pyrene and carbon tetrachloride in methylcyclohexane at 20° C have k = 1 × 10 12 M −1 sec −1. These values are consistent with electron mobilities mesaured by conductivity.

Density Dependence of the Absorption Spectrum of solvated Electrons in Supercritical Ammonia

AbstractPreliminary experiments are reported on the density dependence of the absorption spectrum of the solvated electron in supercritical ammonia. solvated electrons were produced by pulse radiolysis in a heated high pressure optical cell. The intensity of the absorption spectrum diminishes with decreasing the ammonia density, and could be detected at 150°C down to densities of 0.1 g/ml. The shape of the spectrum and its position are only slightly changed indicating that normal solvation even at the low densities is possible. The spectroscopic data can be adequately interpreted by a theoretical molecular model for electron localization in a polar dense fluid.

The Effect of Solvent and of Solutes on the Absorption Spectrum of Solvated Electrons1a

The Effect of Solvent and of Solutes on the Absorption Spectrum of Solvated Electrons^1a