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Electrical conductivity and dielectric properties of silver iodide doped silver ion mixed-former conducting glasses have been studied in this paper. The frequency dependence of conductivity has been analyzed following the random free-energy barrier model. The charge carrier relaxation time and the activation energy for relaxation have been determined for the present glasses. The applicability of Barton-Nakajima-Namikawa relation has been tested for the present glasses using the results obtained from random free-energy barrier model. The scaling of the conductivity spectra has been performed to understand the effect of temperature as well as composition on the relaxation dynamics. The dielectric data have been analyzed employing the Cole-Cole function, and parameters such as dielectric strength and Cole-Cole exponent have been obtained. The electrode polarization phenomenon for the present glass samples has been studied depending on temperature as well as composition. The different characteristic transitions concerning electrode polarization related to the charge transport at the interface have been obtained and are correlated to the bulk behavior. An estimation of the dc conductivity has been obtained using the result obtained from electrode polarization study and is observed to be very close to the experimental values.

Transport properties of silver selenomolybdate glassy ionic conductors have been reported for wide composition and temperature ranges. It has been observed that the transport properties of these glasses depend strongly on the modifier content as well as on the glass formers ratio. A direct correlation between the ion transport and the modification of the glass structure has been predicted. Transport properties of these glasses are also strongly influenced by the existence of dual character of SeO2 as a glass former and a glass modifier. Structural models for different compositions have also been proposed.

Structure and dielectric properties of the glasses of compositions yAg2O-(1-y)(xSeO2-(1-x)MoO3) with varying modifier oxide and glass formers ratio have been reported in this paper. Fourier transform infrared (FTIR) spectroscopy has been employed to investigate the effect of SeO2 content on the glass network structure. The existence of different characteristic absorption bands corresponding to the vibration of SeO32− anions, isolated MoO6 units and crystalline molybdate octahedra, has been ascertained from FTIR spectra. It has been observed that the modification of the glass network structure occurs with change of SeO2 content, which reveals the dual role of SeO2 as a network modifier and a network former depending on composition. The dielectric constant as well as dielectric strength increases gradually with the increase of SeO2 content for low modifier oxide content (y), whereas they show a maximum for intermediate and highly modified glasses. The variation of the dielectric parameters correlates direct...

Non-Debye relaxation in superionic AgI–Ag2O–SeO2 glasses has been investigated as a function of frequency and temperature. The experimental data have been analyzed in the framework of complex dielectric permittivity and complex electric modulus formalisms. The dielectric permittivity data have been well interpreted using the Havriliak–Negami function. The electric modulus data have been analyzed by invoking Kohlrausch–Williams–Watts function and various parameters describing the relaxation mechanism have been obtained. The temperature and compositional variation in relaxation times and the activation energy, obtained from dielectric permittivity as well as from electric modulus data, have been compared. The low value of stretched exponential parameter implies a highly nonexponential nature of relaxation and is attributed to the correlated ionic motion. The values of the stretched exponential parameter are observed to be independent of temperature as well as composition. Different scaling formalisms have b...

The production of metastable (3P0) mercury atoms in the quenching of mercury resonance radiation has been investigated with N2, H2, C2H4, C2H6, O2, and CO2. Metastable atoms, by virtue of their ability to induce the emission of electrons from a nickel surface, were detected with the first four gases; none was detected with O2 and CO2.

The reaction of Hg(3P1) with ethylene at room temperature has been re‐investigated. Special attention was paid to the effects of the concentrations of ethylene and mercury on the reaction velocity. The results are in general agreement with a mechanism which requires the excited ethylene, produced initially, to decompose both in the gas phase and on the wall. The results are also compatible with the suggestion that a significant fraction of the quenching collisions between ethylene and Hg(3P1) leads to the formation of metastable (3P0) atoms.

The reactions between Hg(3P1) and toluene have been investigated between 150° and 400°C at pressures from 0.4 to 30.5 mm Hg. The gaseous products are H2, CH4, and C2H6. The quantum yield for H2 is 5×10—4 at 150°C and increases to about 10—1 at 400°C. A mechanism based on two types of excited toluene molecules is proposed.

The cross sections for quenching mercury resonance radiation by a number of mono‐ and di‐olefins, acetylenes, substituted olefins, and other compounds containing multiply bonded atoms have been measured. The quenching cross sections of mono‐olefins increase with increasing molecular weight but not with increased branching of the carbon skeleton. The position of the double bond has little or no effect on the cross section. The substitution of fluorine for hydrogen decreases the cross section of olefins. The presence of a second double bond does not alter the cross section. The double bond is more effective when between two carbon atoms than when it is between two nitrogens or carbon and oxygen. The cross sections of acetylenes are essentially the same as those of the corresponding olefins but here the substitution of N for CH does not appear to alter the effective cross section.

The reactions of atomic hydrogen, produced by a discharge, with methyl ether, acetaldehyde, and ethylene oxide have been investigated.The main products of the reactions are: from methyl ether—CH4,CO,H2O,C2H6, and HCHO;from acetaldehyde—CH4,CO, and C2H6;from ethylene oxide—CH4,CO, and CH3CHO.The mechanisms of the reactions are discussed in detail and it is concluded that the primary reactions are: H+CH3OCH3→H2+CH3OCH2E=7.0 kcal.H+CH3CHO →H2+CH3COE≤6.0 kcal.H+(CH2)2O →H2+C2H3OE=8.5 kcal., and that the main secondary reactions in all cases are of the atomic cracking type: H+CH3OCH2→CH3+CH3O,H+CH3CO →CH3+CHOor →CH4+CO,H+C2H3O →CH3CHOor →CH4+CO.

Total effective cross sections have been measured for 22 compounds in the processes 3P1 ← 3P0 and 3P1 ← 1S0, by which mercury resonance radiation is quenched. The compounds include the methylamines, methyl halides, methyl alcohol, dimethyl ether, H2S, ethyl mercaptan, dimethyl sulfide, ethylene oxide, cyclo‐paraffins, and dimethyl mercury. The cross sections varied from less than 0.01A2 (fluoroform) to 46A2 (dimethyl mercury). In general σQ2 is increased when a carbon atom is replaced by oxygen and even larger increases occur when the substituting atom or group is, or contains, nitrogen, sulfur, or mercury. The presence of halogens, except fluorine, increases σQ2; the introduction of fluorine reduces the cross section.

The mercury photo‐sensitized reactions of diethyl ether have been investigated in a circulatory system at 35°C and between 9‐ and 193‐mm pressure. The principal products are hydrogen and C8H18O2; smaller amounts of CO, CH4, C2H6, and aldehydes are formed. The quantum yield for ether disappearance is about 2.0 initially but decreases with the duration of the experiment. In low pressure experiments the hydrogen produced initially is consumed in the later stages of the experiment and ultimately vanishes. The decrease in rate and the consumption of hydrogen in the late stages of the reaction are not caused by the accumulation either of polymer on the wall or to hydrogen and/or CO in the system. The nature of the reaction is altered by interrupting the experiment thus indicating the occurrence of a dark reaction. The initial stages may be explained by either a C–H split followed by ``atomic cracking'' or by reactions involving an active ether molecule.

The decomposition of liquid decane photo‐sensitized by dissolved mercury to λ2537 has been investigated between 0° and 134°C. The only important products are hydrogen and eicosanes. The initial act is probably the breaking of a C–H bond with the production of a hydrogen atom and a decyl radical. The decyl radicals recombine to form eicosanes without undergoing any detectable disproportionation to form decene and decane. The quantum yield of the production of hydrogen is about 0.10 at 0°C and increases to 0.45 at 134°C. The low quantum yield and its temperature dependence may be due to either an inefficient primary act or to recombination of hydrogen atoms and decyl radicals in liquid ``cages.''

The effect of pressure on the initial stages of the mercury photosensitized reactions of ethane has been investigated at room temperature. The production of methane increases with decreasing ethane pressure and is inhibited by the presence of molybdenum oxide. It has been shown that hydrogen atoms are produced in the initial stages of the reaction. It is concluded that the initial step is a C–H split and that an active ethane molecule is not formed. The dependence of quantum yields on pressure indicates that the initial step is about 100 percent effective and that inefficiency is caused by recombination of H and C2H5 resulting in the formation of ethane at high pressures by deactivation, and in the formation of methyl radicals at lower pressures.

The mercury photosensitized reactions of methyl alcohol have been investigated at pressures of 30 and 100 mm Hg and over a temperature range from 25° to 500°C. Below 400°C the products are almost entirely hydrogen and ethylene glycol and small amounts of carbon monoxide, formaldehyde and methane. It has been established that the primary step in the reaction mechanism is Hg(3P1)+CH3OH→CH2OH+H+Hg(1S0). There is considerable supporting evidence that the alternative split into H+CH3O does not occur.Above 400°C the rates of production of CH2O and CO become significant and increase with rising temperature which has been explained by the fact that the decomposition of the CH2OH radical is taking place. An activation energy of 29 kcal. has been obtained for this decomposition reaction.

The effective cross sections of the paraffin hydrocarbons from ethane to n‐heptane in quenching mercury resonance radiation (λ2537) have been measured by the technique of Zemansky. The effective cross section of ethane is much smaller than the value previously found by Bates. Neopentane is reasonably efficient in quenching λ2537 although it is not decomposed readily by Hg(3P1) atoms. Increase in molecular weight and, up to a point, in branching of the carbon skeleton are accompanied by increases in the effective cross section. The quenching efficiency of the paraffins depends on the number and type of C–H bonds in the molecule and is not primarily a function of the number of carbon atoms or C–C bonds. The effective quenching diameters of the C–H bonds are: primary 0.05 to 0.10A, secondary 0.50 to 0.65A, and tertiary 1.3A; the actual values depending to some extent on the nature of the rest of the molecule. The number of collisions necessary for quenching to occur on primary, secondary, and tertiary C–H bo...

The mercury photosensitized reactions of propane have been investigated at room temperature between 0.7 and 84.5 mm Hg. At high pressures the products consisted almost entirely of hexane and hydrogen but at low pressures methane and C2 and C4 hydrocarbons were produced in increasing amounts. The production of methane was much less than in the similar reactions of ethane. The effect of pressure on the nature of the reaction can be accounted for by a C–H split followed by atomic cracking and recombination reactions as proposed by Steacie and Dewar, but the difference in the products from propane and ethane make it likely that the reaction proceeds, at least in part, by the formation of an active molecule. At low pressures the rate of propane disappearance is retarded and the extent of C–C split increased by the addition of hydrogen. The effect of added hydrogen is explained by an increase in the rates of recombination of hydrogen atoms and of atomic cracking reactions.

Deuterium labeled isobutane (CH3)3CD was pyrolyzed to generate (CH3)3C and CH2CD(CH3)2 radicals. The competition between reactions (5) and (6) was studied by isotopic analysis of the hydrogen, methane, and isobutene fractions. CH2CD(CH3)2→CH2=C(CH3)2+D CH2CD(CH3)2→CH2=CDCH3+CH3.Reaction (5) was found to be of negligible importance relative to reaction (6) up to 540°C and it is concluded that previous estimates of k5/k6 (in the nondeuterated species) are too high by at least an order of magnitude. The expulsion of molecular hydrogen by isobutyl or t‐butyl does not occur in competition with other unimolecular reactions of these radicals.

The relative rates of abstraction by CD3 radicals of primary, secondary, and tertiary H atoms have been measured. Using a standard rate constant for abstraction of D from acetone‐d6, the following rate constants are obtained: k(mole−1cc sec−1)CD3+CD3COCD3→CD4+CD2COCD33.5×1010T12exp(−11 100/RT),(2)CD3+(CH3)3)CD→CD4+(CH3)3C0.88×1010T12exp(−9200/RT),(3)CD3+(CH3)3CD→CD3H+CH2–CD(CH3)24.38×1010T12exp(−11 100/RT),(4)CD3+(CH3)3CH→CD3H+(CH3)3C0.70×1010T12exp(−7600/RT).(10) Isotope effects obtained are, for secondary H and D in propane kH/kD=1.04exp(1400/RT), and for tertiary H and D in isobutane kH/kD=0.80 exp(1600/RT). These isotope effects are within experimental error of that given by the general expression for the deuterium isotope effect previously proposed kH/kD=exp(1500/RT), and are in excellent correspondence with the theoretical treatment of Johnston and Rapp.

An investigation of the acetone photolysis in the ``continuum'' and in the ``banded'' region has been made in clean quartz vessels and in vessels coated with potassium chloride and with lead. No appreciable change in the C2H6/CO ratio occurs in the coated vessels. This is surprising since biacetyl formation is apparently at least partly heterogeneous, and the ratio would be expected to be sensitive to the condition of the surface.A few experiments were also made on the mercury photosensitized decomposition of acetone. Very high C2H6/CO ratios were found. It is concluded that this is due merely to higher absorbed intensities for a given incident intensity.