Photoconductivity of γ-irradiated methyltetrahydrofuran glass at 77 °K

Baverstock, Keith; Dyne, P. J.

doi:10.1139/v70-365

Cited by 21 publications

(4 citation statements)

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“…This wavelength dependence is in reasonable agreement with previous work. 8 The quoted error for the quantum efficiency is estimated accuracy, not precision of measurement. It is noteworthy that the quantum efficiency curve rises more steeply at 4.2°K vs 77°K and apparently has a slightly higher energy onset at 4.2°K.…”

Section: B Wavelength Dependence Of the Photo Current And Of Opticalmentioning

confidence: 99%

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Energy Level Structure of Trapped Electrons in Methyltetrahydrofuran Glass from Photoconductivity and Optical Bleaching Studies

Huang

Eisele

Lin

et al. 1972

The Journal of Chemical Physics

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Wavelengthselective bleaching of the optical spectra of trapped electrons in organic glasses. II.Electronelectron double resonance study of trapped electrons in γirradiated 2methyltetrahydrofuran glass: Magnetic energy transfer between two different spin systems Electrons are trapped in 'Y irradiated methyltetrahydrofuran (MTHF) glass at 77°K. Monochromatic photoexcitation produces photoconductivity and optical bleaching with a threshold near 780 nrn (1.6 eV) and a peak near 520 nm (2.4 eV). This transition is linear in light intensity and independent of temperature between 77 and 4.2°K, so it is interpreted as a one photon transition directly to the conduction band or to an autoionizing state. Effective double beam photoexcitation discloses a two photon transition which depends on the light intensity squared. The first photon corresponds to the well-known optical absorption of trapped electrons in MTHF at 1.0 eV. This transition is interpreted as a 1s~2p type. The 2p state then presumably crosses to a 2s-type state from which the second photon is absorbed. The wavelength dependence of the second photon transition shows a peak at 950 nm (1.3 eV) and a threshold near 1150 nm (1.1 eV). The temperature of both optical bleaching and photoconductivity under ir photoexcitation shows that population of the 2s-type state involves an activation energy ~O.OOl eV. The deduced energy level structure agrees well with theoretical calculations based on a semicontinuum model for trapped electrons in glassy matrices. Compared to more polar matrices like ice, both experiment and theory indicate that in less polar matrices like MTHF the short-range charge-dipole interactions are relatively less important compared to the long range polarization interactions and cause the bound excited states to be relatively more stable and the ground state to be relatively less stable.

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Section: B Wavelength Dependence Of the Photo Current And Of Opticalmentioning

confidence: 99%

“…8 Their work seems mainly oriented towards the phenomena of induced photocurrents. However, there are some important differences with respect to photocurrent profiles and the interpretation of the ir photocurrent.…”

Section: Comparison With Previous Workmentioning

confidence: 99%

Energy Level Structure of Trapped Electrons in Methyltetrahydrofuran Glass from Photoconductivity and Optical Bleaching Studies

Huang

Eisele

Lin

et al. 1972

The Journal of Chemical Physics

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“…Thus comparison of optical absorption and photoconductivity spectra is expected to provide information on the energy level structure of trapped electrons. For trapped electrons in polar glasses several photoconductivity studies have been made (2)(3)(4)(5)(6)(7)(8)(9) and theoretical approaches have been attempted to interpret these experimental results (10,11). On the other hand, only a few photoconductivity studies have been done for trapped electrons in nonpolar organic glasses (12,13).…”

Section: Introductionmentioning

confidence: 99%

A photoconductivity study of trapped electrons in γ-irradiated hydrocarbon glasses at 77 K

Okabe¹,

Kimura²,

Fueki³

1983

Can. J. Chem.

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Photoconductivity spectra of trapped electrons in γ-irradiated 3-methylpentane, 2-methylpentane, 3-methylheptane, and 3-methylpentane–methylcyclohexane (1:9 volume ratio) glasses at 77 K were measured. From the comparison of photoconductivity and optical absorption spectra in these systems we have obtained relative values of quantum efficiencies for a trapped electron in the ground state to be excited to the conduction band by photo-induced transition. For electrons stably trapped, we have measured the ranges of trap depths from the shallowest to the deepest in these systems.

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“…A number of studies have been made o n the optical absorption spectra of trapped electrons in a neat MTHF glass (6), but there have been only a few photoconductivity studies of trapped electrons in this matrix (7,8).…”

Section: Introductionmentioning

confidence: 99%

Comparison of photoconductivity and optical absorption spectra of trapped electrons in γ-irradiated 2,2,4-trimethylpentane/2,2-dimethylbutane/2-methyltetrahydrofuran mixture glasses at 77 K

Kimura¹,

Hirao²,

Okabe³

et al. 1984

Can. J. Chem.

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TOYOAKI KIMURA, KAZUNOBU HIRAO, NAOTO OKABE, and KENJI FUEKI. Can. J. Chem. 62, 64 (1984). Optical absorption and photoconductivity spectra of trapped electrons in y-irradiated 2,2,4-trimethylpentane (TMP)/2,2-dimethylbutane (DMB)/2-methyltetrahydrofuran (MTHF) mixture glasses at 77 K have been measured. It is found that the magnitude of the photocurrent increases with decreasing MTHF concentration, which is ascribed to the increase in electron mobility with decreasing MTHF concentration in TMP/DMB/MTHF systems. It is also found that the photoconductivity spectra shift to the lower energy side with decreasing MTHF concentration. Although the photoconductivity spectrum in the neat MTHF system is separated from the corresponding optical absorption spectrum, the spectrum becomes closer to the latter with decreasing MTHF concentration in TMP/DMB/MTHF systems. This result indicates that the extent of bound-free transitions increases relative to bound-bound transitions with decreasing MTHF concentration for the photon absorption process of trapped electrons in TMP/DMB/MTHF systems.TOYOAKI KIMURA, KAZUNOBU HIRAO, NAOTO OKABE et KENJI FUEKI. Can. J. Chem. 62, 64 (1984). On a mesurC a 77 K les spectres d'absorption optique et de photoconductivitC des tlectrons piCgCs dans un melange vitreux de trimCthyl-2,2,4 pentane (TMP)/dimtthyl-2,2 butane (DMB)/mCthyl-2 tktrahydrofuranne (MTHF) irradiC aux rayons y. On a trouvC que l'intensitt du photocourant augmente lorsque la concentration du MTHF diminue, ce qui l'on attribue a une augmentation de la mobilitk de l'tlectron lorsque diminue la concentration du MTHF dans le systbme TMP/DMB/MTHF. On a Cgalement trouvt que les spectres de photoconductivitt glissent du cat6 de faible Cnergie lorsque la concentration de MTHF diminue. Bien que le spectre de photoconductivitC du systeme MTHF pur soit separe du spectre correspondant d'absorption optique, ces deux spectres se rapprochent beaucoup lorsque la concentration de MTHF du systkme TMP/DMB/MTHF diminue. Ce rCsultat indique que le taux de transitions liaison-libre augmente par rapport aux transitions liaison-liaison lorsque la concentration de MTHF diminue dans le processus d'absorption du photon pour les electrons piCgCs dans le systbme TMP/DMB/MTHF.[Traduit par le journal] I

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Photoconductivity of γ-irradiated methyltetrahydrofuran glass at 77 °K

Cited by 21 publications

References 8 publications

Energy Level Structure of Trapped Electrons in Methyltetrahydrofuran Glass from Photoconductivity and Optical Bleaching Studies

Energy Level Structure of Trapped Electrons in Methyltetrahydrofuran Glass from Photoconductivity and Optical Bleaching Studies

A photoconductivity study of trapped electrons in γ-irradiated hydrocarbon glasses at 77 K

Comparison of photoconductivity and optical absorption spectra of trapped electrons in γ-irradiated 2,2,4-trimethylpentane/2,2-dimethylbutane/2-methyltetrahydrofuran mixture glasses at 77 K

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