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

1982 ◽  
Vol 60 (18) ◽  
pp. 2342-2350 ◽  
Author(s):  
Ah-Dong Leu ◽  
Kamal N. Jha ◽  
Gordon R. Freeman
Keyword(s):  
Optical Absorption ◽  
Pure Water ◽  
High Energy ◽  
Band Width ◽  
Primary Alcohols ◽  
Solvated Electrons ◽  
Tertiary Butyl ◽  
Composition Effects ◽  
Tertiary Alcohols ◽  
Alcohol Water

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.

scholarly journals Optical absorption spectra of solvated electrons in 1-butylamine–water mixed solvents

1995 ◽  
Vol 73 (12) ◽  
pp. 2126-2130 ◽  
Author(s):  
Yixing Zhao ◽  
Gordon R. Freeman
Keyword(s):  
Optical Absorption ◽  
Absorption Spectra ◽  
Pure Water ◽  
Mixed Solvents ◽  
Binary Solvents ◽  
Optical Absorption Spectra ◽  
Solvated Electron ◽  
Solvated Electrons ◽  
Selective Solvation ◽  
Ideal Mixing

The optical absorption spectra of es− in 1-butylamine–water mixed solvents increase smoothly in energy and intensity as the water content is increased, with the exception of a small decrease in intensity on going from 95 to 100 mol% water. At 298 K the value of Gεmax increases from 1.42 × 10−21 m2/16 aJ (8.6 × 103 es−L/100 eV mol cm) in pure 1-butylamine to 8.3 × 10−21 m2/16 aJ (50 × 103 es−L/100 eV mol cm) in pure water, and the value of EAmax increases from 115 zJ (0.72 eV) to 278 zJ (1.74 eV). In the pure amine, if G(es−) = 0.27, then εmax = 5.3 × 10−21 m2/es− (3200 m2/mol). The solvent composition dependences of Gεmax and EAmax indicate little selective solvation of es− by water; this might be due to relatively "ideal" mixing of water and amine in the binary solvents. The temperature coefficient −dEAmax/dT = 0.43 zJ/K in pure 1-butylamine, 0.47 in pure water, and has a minimum of 0.27 in the 50:50 mixture. Keywords: 1-butylamine–water mixed solvents, optical absorption spectra, solvated electron, temperature dependence.

Effect of solvent structure on electron reactivity: 2-propanol/water mixtures

1988 ◽  
Vol 66 (7) ◽  
pp. 1706-1711 ◽  
Author(s):  
Yadollah Maham ◽  
Gordon R. Freeman
Keyword(s):  
Electron Transfer ◽  
Secondary Alcohol ◽  
Mixed Solvents ◽  
Trap Depth ◽  
Large Change ◽  
Solvent Composition ◽  
Solvated Electrons ◽  
Tertiary Alcohols ◽  
Alcohol Water ◽  
Small Change

The reactivity of solvated electrons [Formula: see text] with efficient (nitrobenzene, acetone) and inefficient (phenol, toluene) scavengers is affected greatly by the solvent composition in 2-propanol/water mixed solvents. 2-Propanol is the only secondary alcohol that is completely miscible with water. The variation of the nitrobenzene rate constant k2 with solvent composition displays four viscosity zones, as in primary and tertiary alcohol/water mixtures. In zone (c), where the Stokes–Smoluchowski equation applies, the nitrobenzene k2 values in the secondary alcohol/water mixtures are situated between those in the primary and tertiary alcohols, due to the relative values of the dielectric permittivity ε. The charge–dipole attraction energy varies as ε−1.The two water-rich zones (c) and (d) are characterized by a large change of viscosity η and a small change in [Formula: see text] solvation energy (trap depth) Er; here k2 for all the scavengers correlates with the inverse of the viscosity. In the two alcohol-rich zones (a) and (b) the change of η is small but that of Er is large; here k2 of inefficient scavengers correlates with the inverse of Er, due to the difficulty of electron transfer out of deeper traps. Activation energies E2 and entropies [Formula: see text] also show composition zone behaviour. The value of [Formula: see text] is more negative for less efficient scavengers; E2 varies less and does not correlate with reactivity or Er. Electron transfer from solvent to inefficient scavenger is driven by solvent rearrangement around the reaction center, reflected in [Formula: see text].

Article

1998 ◽  
Vol 76 (4) ◽  
pp. 411-413
Author(s):  
Yixing Zhao ◽  
Gordon R Freeman
Keyword(s):  
Absorption Spectrum ◽  
Optical Absorption ◽  
Temperature Dependence ◽  
Optical Absorption Spectrum ◽  
Infrared Light ◽  
Solvated Electron ◽  
Solvated Electrons ◽  
Tert Butanol ◽  
Solvent Dependence ◽  
Increasing Temperature

The energy and asymmetry of the optical absorption spectrum of solvated electrons, es- , change in a nonlinear fashion on changing the solvent through the series HOH, CH3OH, CH3CH3OH, (CH3)2CHOH, (CH3)3COH. The ultimate, quantum-statistical mechanical, interpretation of solvated electron spectra is needed to describe the solvent dependence. The previously reported optical spectrum of es- in tert-butanol was somewhat inaccurate, due to a small amount of water in the alcohol and to limitations of the infrared light detector. The present note records the remeasured spectrum and its temperature dependence. The value of the energy at the absorption maximum (EAmax) is 155 zJ (0.97 eV) at 299 K and 112 zJ (0.70 eV) at 338 K; the corresponding values of G epsilon max (10-22 m2 aJ-1) are 1.06 and 0.74. These unusually large changes are attributed to the abnormally rapid decrease of dielectric permittivity of tert-butanol with increasing temperature. The band asymmetry at 299 K is Wb/Wr = 1.8.Key words: optical absorption spectrum, solvated electron, solvent effects, tert-butanol, temperature dependence.

CONDUCTANCES OF LITHIUM NITRATE SOLUTIONS IN ETHYL ALCOHOL AND ETHYL ALCOHOL - WATER MIXTURES AT 25.0 °C.

1956 ◽  
Vol 34 (9) ◽  
pp. 1232-1242 ◽  
Author(s):  
A. N. Campbell ◽  
G. H. Debus
Keyword(s):  
No Value ◽  
Ethyl Alcohol ◽  
Pure Water ◽  
Lithium Ion ◽  
Water Molecules ◽  
Lithium Nitrate ◽  
Absolute Alcohol ◽  
Pure Alcohol ◽  
Alcohol Water ◽  
Nitrate Solutions

The conductances of solutions of lithium nitrate in 30, 70, and 100 weight per cent ethyl alcohol have been determined at concentrations ranging from 0.01 molar up to saturation, at 25 °C. The densities and viscosities of these solutions have also been determined. The data have been compared with the calculated conductances obtained from the Wishaw–Stokes equation. The agreement is fairly good up to, say, 2 M, for all solvents except absolute alcohol. In the latter solvent there is no value of å, the distance of closest approach, which will give consistent values of the equivalent conductance. In passing from pure water to pure alcohol, the value of å increases progressively and this we attribute to a change in the solvation of the lithium ion from water molecules to alcohol molecules. Some further calculations incline us to the view that the nitrate ion, as well as the lithium ion, is solvated to some extent, at least in alcohol.

Freeze-drying of liposomes using tertiary butyl alcohol/water cosolvent systems

2006 ◽  
Vol 312 (1-2) ◽  
pp. 131-136 ◽  
Author(s):  
JingXia Cui ◽  
ChunLei Li ◽  
YingJie Deng ◽  
YongLi Wang ◽  
Wei Wang
Keyword(s):  
Freeze Drying ◽  
Butyl Alcohol ◽  
Tertiary Butyl Alcohol ◽  
Tertiary Butyl ◽  
Alcohol Water

Is there any Correlation between the Mobility and the Absorption Spectra of Solvated Electrons in Polar Solvents?

2000 ◽  
Vol 214 (10) ◽  
Author(s):  
P. Krebs
Keyword(s):  
Absorption Spectrum ◽  
Optical Absorption ◽  
Absorption Spectra ◽  
Optical Absorption Spectrum ◽  
Chem Phys ◽  
Solvated Electrons ◽  
Polar Solvents ◽  
Excess Electrons

Some years ago Jay-Gerin and Ferradini attempted to establish a correlation between the optical absorption spectrum and the mobility of excess electrons in various polar solvents (J. Chem. Phys.

Solvent effects on the reactivity of solvated electrons with ammonium and nitrate ions in 1-butanol–water solvents

1993 ◽  
Vol 71 (9) ◽  
pp. 1303-1310 ◽  
Author(s):  
Ruzhong Chen ◽  
Gordon R. Freeman
Keyword(s):  
Solvent Effects ◽  
Pure Water ◽  
Reaction Rates ◽  
Dielectric Relaxation Time ◽  
Unusual Behavior ◽  
Solvated Electrons ◽  
Water Solvent ◽  
Electrical Conductances ◽  
Average Size ◽  
Effective Reaction

Values of the rate constants, k2 (106 m3 mol−1 s−1), of solvated electrons,[Formula: see text] with several related salts, in pure water and pure 1-butanol solvents at 298 K are, respectively, as follows: LiNO3, 9.2, 0.19; NH4NO3, 10, 8.3; NH4ClO4, 1.5 × 10−3, 12 in 20 mol% water; LiClO4, 1.0 × 10−4, < 1.0 × 10−4. The value of [Formula: see text] in water solvent is 48 times larger than that in 1-butanol solvent, whereas [Formula: see text] in water is 10−4 times smaller than the value in 1-butanol. This enormous reversal of solvent effects on [Formula: see text] reaction rates is the first observed for ionic reactants. The solvent participates chemically in the [Formula: see text] reaction, and the overall rate constant increases with increasing viscosity and dielectric relaxation time. This unusual behavior is attributed to a greatly increased probability of reaction of an encounter pair with increasing duration of the encounter. Effective reaction radii κRr for [Formula: see text] and [Formula: see text] were estimated with the aid of measured electrical conductances of the salt solutions in all the solvents. Values of κRr are (2–7) × 10−10 m, except for NH4,s+ in 100 and 99 mol% water, which are 2.6 and 2.7 × 10−14 m, respectively. The effective radii of the ions for mutual diffusion increase with increasing butanol content of the solvent, from ~50 pm in water to ~150 pm in 1-butanol, due to the increasing average size of the molecules that solvate the ions.

Effect of alkylation of ammonia on the optical band shape of solvated electrons

1982 ◽  
Vol 60 (14) ◽  
pp. 1809-1814 ◽  
Author(s):  
Fang-Yuan Jou ◽  
Gordon R. Freeman
Keyword(s):  
Optical Absorption ◽  
Temperature Coefficient ◽  
High Energy ◽  
Correlation Factor ◽  
Theoretical Treatment ◽  
Band Shape ◽  
Optical Absorption Band ◽  
High Energy Side ◽  
Half Height ◽  
Energy Side

At 200 K the width at half height, W1/2, of the e−solv optical absorption band in n-propyl amine is 2.1-fold greater than that in ammonia. Three quarters of the broadening occurs on the high energy side of the band. The energy Er at half height on the low energy side of the band is nearly the same in the amine as in ammonia, while Eb, the energy at half height on the high energy side, is 42% greater in the amine. The temperature coefficient dEAmax/dT is 1.8-fold greater in the amine than in ammonia. The larger width is consistent with there being a less uniform distribution of localization sites in the system, and the larger temperature coefficient implies that the sites are more easily disturbed by thermal agitation. A quantum statistical mechanical model, such as the one begun by Simons, is needed to extend the theoretical treatment of e−solv spectra. The correlation between optical absorption energies of e−solv and the structure of the solvent, as partially reflected in the Kirkwood correlation factor, is re-emphasized.

scholarly journals Low-frequency Raman Spectroscopy of Aqueous Solutions of Aliphatic Alcohols

2001 ◽  
Vol 56 (8) ◽  
pp. 529-536 ◽  
Author(s):  
Koji Ydoshida ◽  
Toshio Yamaguchi
Keyword(s):  
Aqueous Solutions ◽  
Raman Spectra ◽  
Mole Fraction ◽  
Water Clusters ◽  
Pure Water ◽  
Low Frequency ◽  
Isosbestic Point ◽  
X Ray Diffraction ◽  
Alcohol Water ◽  
Solvent Clusters

Abstract Low-frequency Raman spectra have been measured at room temperature as functions of the alcohol mole fraction in aqueous solutions of methanol, ethanol, 1-propanol, 2 -propanol, and /er/-butylalcohol (TBA). Intrinsic Raman spectra R (ῡ) were obtained from depolarized Rayleigh wing spectra. Isosbestic points have been observed in R (ῡ) of the aqueous solutions of ethanol, 1-propanol, and 2 -propanol, suggesting that the structure o f the solutions is characterized by individual alcohol aggregates and water clusters without a significant amount of alcohol-water mixed aggregates. The R (ῡ) spectra have been expressed as R (ῡ ,x ) = w R (ῡ ,0 ) + aR(D, 1), where R(ῡ, 0) and R(ῡ, 1) are those for pure water and pure alcohols, respectively, and x is the mole fraction of alcohols. The coefficients w and a show the inflection points at characteristic alcohol mole fractions, where microhetrogeneity and structural transition of the solvent clusters take place, as previously shown by X-ray diffraction. In the aqueous solutions of methanol, where no microhetrogeneity takes place, no clear isosbestic point in R(ῡ) has been observed. For aqueous solutions of TBA, an isosbestic point in R(ῡ) has appeared when xTBA > 0.05. Two inflections points in the coefficients have been observed at xTBA « 0.1 and 0.35; the former composition corresponds to the transition composition from the TBA-TBA intermolecular contact to the TBA water molecular association, as previously reported by neutron diffraction.

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