Tunneling reactions of trapped electrons with added electron acceptors in alcohol glasses at 77 K

Miller, John R.

doi:10.1021/j100496a004

Cited by 45 publications

(9 citation statements)

References 8 publications

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“…This is possible because the traps from which these electrons tunnel are presumed to be extremely shallow. 35 The above identification of the transient infrared absorption agrees with the explanation which has been given by Dolivo and Kevan36 for the red shifts (relative to the spectra at 4.2 K) which they observed in the localized electron spectra obtained subsequent to the irradiation of both CH3OH and CD3OD at 1.6 K. These red shifts are, however, smaller than those which were observed in this work. 37 The widths at half-maximum which were measured by Kevan and Dolivo at 1.6 K are also smaller than those at 4.2 K while, in this work, the widths at half-maximum of the spectra which are seen 100 ns after the beginning of the electron pulse at 6 K are larger than those of the spectra which result from steady-state irradiation at 4.2 K. Additionally, the results demonstrated in Figure 3 require, in the context of this interpretation of the transient infrared absorption, that the number of very shallow traps which are initially present in vitreous methanol decreases with increasing temperature.…”

Section: Discussionsupporting

confidence: 92%

Very low temperature pulse radiolysis. Protiated and perdeuterated methanol glasses at 6 K

Perkey¹,

Smalley²

1979

J. Phys. Chem.

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Publication costs assisted by Brookhaven National Laboratory Spectra resulting from the pulse radiolysis of glasses CH3OH and CD3OD at 6 K were observed. The absorption maxima of these spectra (625 nm for CH3OH and 720 nm for CD3OD-observed 100 ns after the beginning of the electron pulse) are only slightly red shifted from the absorption maximum obtained when either of these alcohols is y irradiated at 4.2 K (i.e., 600 nm). Bleaching studies indicate that these y radiolysis spectra are composed of a visible part which is due to solvated electrons and an infrared part which is due to trapped electrons.The infrared portions of the pulse radiolysis spectra at 6 K are enhanced compared to the above y radiolysis spectra, and they decay to the latter spectra by a process which is approximately first order. Benzyl chloride also reduces the infrared absorptions which are produced by an electron pulse at 6 K more effectively than it reduces the visible absorptions. The species which is responsible for the transient infrared absorption at 6 K is tentatively identified as an electron localized in either a very shallow trap or a trap which is geminate to its parent cation. In either case, since these pulse radiolysis spectra are fully developed immediately after the electron pulse, it is concluded that electrons are localized in preexisting potential wells which may be either deep or shallow in vitreous methanol.

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Section: Discussionsupporting

confidence: 92%

Very low temperature pulse radiolysis. Protiated and perdeuterated methanol glasses at 6 K

Perkey¹,

Smalley²

1979

J. Phys. Chem.

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“…In photoionization, the Franck-Condon effect must be considered, and the difference is attributed to the additional energy for nuclear relaxation required in photoionization. 55,56 V. CONCLUSION We measured positron lifetime spectra for PE/CPE polymer blends as functions of external electric field, temperature, and positron irradiation time. Complimentary information on the positron states and annihilation sites was obtained by positron mobility and coincidence Doppler-broadening measurements.…”

Section: Effects Of Positron Irradiation On Ps Formationmentioning

confidence: 99%

Positronium formation in a polymer blend of polyethylene and chlorinated polyethylene

et al. 2001

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We discuss positronium ͑Ps͒ formation in a polymer blend system consisting of low-density polyethylene ͑PE͒ and chlorinated polyethylene ͑CPE, random copolymer with a chlorine weight content of 35%͒. Positron lifetime measurements were performed as a function of CPE composition ͑0-100%͒, electric field (F ϭ0 -40 kV/cm), temperature (Tϭ30-300 K), and positron irradiation time (tϭ0 -110 h) at Tϭ75 K, and room temperature. We note that Ps formation occurs by recombination of electron-positron pairs with both small ͑Շ3 nm͒ and large ͑տ3 nm͒ initial separations. At low temperatures, pairs with large separations are formed not only in the positron spur ͑blob͒ but also as a result of coupling of a thermalized positron with one of the localized electrons produced by positron irradiation. For PE, the contribution of the latter process to Ps formation appears as a gradual increase in relative intensity of the long-lived ortho-positronium (o-Ps) component as a function of positron irradiation time. The addition of CPE appreciably reduces the contribution from pairs with large separations, and Ps formation in pure CPE occurs exclusively from pairs with small initial separations, much less influenced by external parameters such as the temperature and electric field.

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“…The dependence of W on the energy gap e for e > £M is given by the following expression derived by taking the maximal term at low temperatures: *~^~exp(-¿[in(t)-1]) (25) When the temperature is above T0 given by Wp0m0 is not the dominant term and one has to modify eq 25 to include temperature dependence from ) ] (28) This formula is expected to be valid if T is not so high that ( + l)p will have significant temperature dependence. For more details see ref 21. Notice that in this case W behaves exponential in T and not in l/T.…”

Section: T [°K]mentioning

confidence: 99%

“…Miller found evidence for these effects in his early work23 and also in his recent work in alcohol glasses. 25 Recently Beitz and Miller26 studied the free energy relations which were predicted in section II in MTHF glasses at 77 K by looking at electron transfer from a trap to a variety of acceptors. The relative reaction rates vary over 5 orders of magnitude.…”

Section: T [°K]mentioning

confidence: 99%

Theory of electron transfer reactions of solvated electrons

Kestner¹

1980

J. Phys. Chem.

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Tunneling reactions of trapped electrons with added electron acceptors in alcohol glasses at 77 K

Cited by 45 publications

References 8 publications

Very low temperature pulse radiolysis. Protiated and perdeuterated methanol glasses at 6 K

Very low temperature pulse radiolysis. Protiated and perdeuterated methanol glasses at 6 K

Positronium formation in a polymer blend of polyethylene and chlorinated polyethylene

Theory of electron transfer reactions of solvated electrons

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