Selected references:


L. I. Trakhtenberg


"Tunneling Transfer of Atomic Particles in Chemical and Biological Reactions: The Role of Intermolecular Vibrations..."


Journal of Physical Chemistry A, 2014, Vol. 88, No. 11, pp. 1837–1848



Leonid I. Trakhtenberg, Anatoly A. Fokeyev, Alexander S. Zyubin, Alexander M. Mebel, and S. H. Lin


"Matrix reorganization with intramolecular tunneling of H atom: Formic acid in Ar matrix"


J. Chem. Phys. 130, 144502 (2009)




M. V. Basilevsky and V. A. Tikhomirov


"Computation of the tunneling H-transfer reaction kinetics in the fluorene molecular crystal"


Mol. Phys. 106, 2391 (2008)




A. A. Fokeyev, A. S. Zyubin and L. I. Trakhtenberg


"The role of intermolecular vibrations and reorganization of a reaction system in tunneling reactions with H atom transfer. A Debye model for the medium"


Russian Chem. Bulletin 57, 1093 (2008)




M. V. Basilevsky and V. A. Tikhomirov


"Calculation of the kinetics of the photochemical reaction of hydrogen atom transfer in a molecular crystal"


Russian J. Phys. Chem. A, 81, 116 (2007) 




L. I. Trakhtenberg and A. A. Fokeyev


"Pressure and Temperature Dependence of H-Atom Tunneling in the Debye Approximation. Barrier Preparation and Media Reorganization"


J. Phys. Chem. A, 111, 9509(2007)




S.A. Serov, M. V. Basilevsky and V.A. Tikhomirov


"Phonon spectrum of a fluorene molecular crystal"


Russian J. Phys. Chem. A, 81, 291 (2007)




M. V. Basilevsky, G. V. Davidovich  and A. I. Voronin


"The model of level broadening in condensed phase"


J. Chem. Phys. 125, 194514 (2006)




M. V. Basilevsky, G. V. Davidovich, S. V. Titov, and A. I. Voronin


"Non-Markovian modification of the golden rule rate expression"


J. Chem. Phys. 125, 194513 (2006)




L. I. Trakhtenberg, A. A. Fokeyev, S. P. Dolin, A. M. Mebel and S. H. Lin


"Temperature and pressure dependences of tunneling rate constant: density-functional theory potential-energy surface for H-atom transfer in the fluorene-acridine system."


J. Chem. Phys. 123, 114508 (2005)




L. I. Trakhtenberg, A. A. Fokeyev, S. P. Dolin, A. M. Mebel, and S. H. Lin


"Rate constant for H-atom tunneling in the fluoreneacridine system based on DFT potential energy surface"


Chem. Phys. 303, 107 (2004)




L. I. Trakhtenberg


"Theory  of Atom Tunneling Reactions in the Solid Phase"


in Atom Tunneling Phenomena in Physics, Chemistry and Biology, p. p. 33


(Ed.: T. Miyazaki) Atomic, Optical and Plasma Physics, Springer Berlin (2004)




M. V. Basilevsky and M. V. Vener


"Theoretical investigations of proton and hydrogen atom transfer in the condensed phase"


Russian Chem. Rev. 72, 1 (2003)




L. I. Trakhtenberg, A. A. Fokeev and S. P. Dolin


"Hydrogen Atom Tunneling in a FluoreneAcridine System: Effect of the Reactant Reorganization"


Russian Journal of Electrochemistry 39, 37 (2003)




I. Y. Chan, I. Huzeifa, B. Prass and D. Stehlik


"Pressure Studies of the Photodimerization of Oriented Anthracene Pairs in a Dianthracene Crystal: Fast Tunneling of a Heavy Particle"


J. Chem. Phys. 117, 4419 (2002)




L. I. Trakhtenberg, A. A. Fokeyev, S. P. Dolin


"Reagent Reorganization and Promotive Modes in Barrier Preparation for H-Tunneling in Fluorene-Acridine System"


Chem. Phys. Lett. 341, 551 (2001)




V. A. Tikhomirov, A. V. Soudackov, and M. V. Basilevsky


"Enthalpy Surfaces for Hydrogen Atom Transfer in a Molecular Crystal"


J. Phys. Chem. A, 105, 3226 (2001)




G. K. Ivanov, M. A. Kozhushner and L. I. Trakhtenberg


"Theory of temperature dependence of hydrogen tunneling reactions"


Chem. Phys. Lett. 322, 78 (2000)




V. A. Tikhomirov, A. V. Soudackov, M. V. Basilevsky, et. al.


Russian J. Phys. Chem. 73, 270 (1999)




B. Prass, D. Stehlik, I. Y. Chan and A. J. Hallock


"Deuterium Effect on the Pressure Coefficient of Tunneling Rate in the Acridine-Fluorene Solid State Photoreaction System"


J. Phys. Chem. 103, 344 (1999)




L. I. Trakthenberg and V. L. Klochikhin


"Pressure and Temperature Effects on the Kinetics of Tunnel Solid-State Reactions in the Acridine-Fluorene System"


Chem. Phys. 232, 175 (1998)




B. Nickel, K. H. Grellmann, J. S. Stephan and P. J. Walla


"Keto-Enol Tautomerism in the Triplet State of Hydroxyphenylbenzoxazoles in an Alkane Glass: Hydrogen Tunneling and Isotope Effects Down to 2K"


Ber. Bunsenges. Phys. Chem. 102, 436 (1998)




B. Prass, D. Stehlik, I. Y. Chan, L. I. Trakthenberg and V. L. Klochikhin


"Vibration-Assisted Intermolecular Hydrogen Tunneling in Photoreactive Doped Molecular Crystals: Effect of Temperature and Pressure"


Ber. Bunsenges. Phys. Chem. 102, 498 (1998)




L. I. Trakhtenberg and V. L. Klochikhin


"Effect of pressure and temperature on the H-atom tunneling in solid phase chemical reactions. The acridine/fluorene system"


Chem. Phys. 232, 175 (1998)




H. P. Trommsdorff


"Photoinduced and Spontaneous Tunneling in Molecular Solids"


Advances in Chemical Physics Vol. 88, Wiley-Interscience, New York (1997)




E. I. Grigoriev and L. I. Trakthenberg


"Radiation-Chemical Processes in Solid Phase"


CRC Press (1996)




I. Y. Chan, M. S. Dernis, C. M. Wong, B. Prass and D. Stehlik


"High Pressure Studies of the Acridine/Fluorene Photoreaction: Vibration Assisted Tunneling"


J. Chem. Phys. 103, 2959 (1995)




L. Cuff and M. Kertesz


"Theoretical Prediction of the Vibrational Spectrum of Fluorene and Planarized Poly(p-phenylene)"


J. Chem. Phys, 98, 12223 (1994)




V. A. Benderskii, D. E. Makarov and C. A. Wight


"Chemical Dynamics at Low Temperatures"


Advances in Chemical Physics Vol. 88, Wiley-Interscience, New York (1994)




I. Y. Chan, C. M. Wong and D. Stehlik


"Pressure Dependence of the Low-Temperature Tunneling Rate for the Hydrogen Transfer in Acridine-Doped Fluorene Crystals"


J. Chem Phys. 219, 187 (1994)




S. E. Bromberg, I. Y. Chan, D. E. Schilke and D. Stehlik


"High Pressure Studies of a Hydrogen-Transfer Photoreaction in a Crystalline Solid: Acridine/Fluorene"


J. Chem Phys. 98, 6284 (1993)




B. Prass and D. Stehlik


"Comment on 'Generalized Golden Rule Treatment of a Photochemical Solid State Reaction Involving Hydrogen Tunneling '"


Chem. Phys. Lett. 200, 429 (1992)




L. Lavtchieva and Z. Smedarchina


Chem Phys. 160, 211 (1992)




N. D. Sokolov and M. V. Vener


"Proton Tunneling Assisted by the Intermolecular vibration Excitation in Solid State"


Chem. Phys. 168, 29 (1992)




W. Al-Soufi, K. H. Grellmann and B. Nickel


J. Phys. Chem. 95, 10509 (1991)




W. Al-Soufi, K. H. Grellmann and B. Nickel


"Keto-Enol Tautomerization of 2.(2´-Hydroxyphenyl)benzoazole and 2-(2´-Hydroxy-4´methylphenyl)benzoazole in the Triplet State: Hydrogen Tunneling and Isotope Effects. 1. Transient Absorption Kinetics"


J. Phys. Chem. 95, 10503 (1991)




L. Lavtchieva and Z. Smedarchina


"Direct Estimate of the Electronic Coupling Driving the Photochemical Proton Transfer in Acridine-Doped Fluorene Crystal"


Chem. Phys. Lett. 187, 506 (1991)




L Chantranupong and T. A. Wildman


"Golden-Rule Treatment of Hydrogen Abstraction by Photoexcited Acridine Guests in Fluorene Single Crystals"


J. Chem Phys. 94, 1030 (1991)




L. Lavtchieva and Z. Smedarchina


"Generalized Golden Rule Treatment of a Photochemical Solid State Reaction Involving Hydrogen Tunneling"


Chem. Phys. Lett. 184, 545 (1991)




Sh. V. Flomenblit, I. D. Mikheikin and L. I. Trakhtenberg


Dokl Akad. Nauk Phys. Chem. 320, 695 (1991)




N. Hoshi, S. Yamauchi and N. Hirota


"Temperature, Pressure and Deuterium Effects on the Phosphorescence Decay-Rate Constant of Naphthalene in a Single Crystal of Durene"


Chem. Phys. Lett. 169, 326 (1990)




L. I. Trakhtenberg, N. A. Slavinskaya and S. Ya. Pshezhetskii


"The Effect of Dynamic Properties of the Medium on the Kinetics of Solid-State Radical Photodissociation Processes"


Chem. Phys. 134, 127 (1989)




B. Prass, J. P. Colpa and D. Stehlik


"Intermolecular H-Tunneling in a Solid State Photoreaction Promoted by Distinct Low-Energy Nuclear Fluctuation Modes"


Chem. Phys. 136, 187 (1989)




V. I. Goldanskii, V. A. Benderskii and L. I. Trakhtenberg


"Quantum Cryochemical Reactivity of Solids"


Advances in Chemical Physics Vol. LXXV, 349 (1989)




B. Prass


"Wasserstofftunneln und heterogene Photochemie in dotierten Molekülkristallen"


Thesis, Free University Berlin (1988)




N. Hoshi, S. Yamauchi and N. Hirota


"Photochemical Reaction of Quinoxaline in a Single Crystal of Durene. 2. Triplet-State Decay and Reaction Rate Constant"


J. Phys. Chem. 92, 6615 (1988)




B. Prass, J. P. Colpa and D. Stehlik


"Identification of the Lowest Energy Nuclear Fluctuation Mode Promoting the Photochemical H-Transfer Tunneling Reaction in Doped Fluorene Single Crystals "


J. Chem. Phys. 88, 191 (1988)




V. I. Goldanskii, V. N. Fleurov and L. I. Trakhtenberg


Sci. Rev. B. Chem. 9, 59 (1987)




L. I. Trakhtenberg and N. Ya. Shteinshneider


"Role of Orientational Vibrations in Solid-Phase Tunneling Reactions. Intermolecular Vibrations"


Russ. J. of Phys. Chem. 60, 841 (1986)




V. I. Goldanskii


"Quantum Chemical Reactions in the Deep Cold"


Scientific American 254, 46 (1986)




M. Tietje, C. von Borczyskowski, B. Prass and D. Stehlik


"Tunneling in Photochemical Solid State H-Transfer. Temperature Dependence of the H-Abstraction Rate in Phenazine Doped Fluorene Single Crystals"


Chem. Phys. Lett. 127, 475 (1986)




G. Bartel, A. Eychmüller and K. H. Grellmann


"Experimental Studies of Hydrogen Tunneling. Utilization of Large Effects in a Mechanistic Study of a Hydrogen Shoft Reaction"


Chem. Phys. Lett. 118, 568 (1985)




M. Nack, M. Tietje, A. Gutsze, J. P. Colpa, B. Prass, D. Stehlik and H.-M.Vieth


"Tunneling in the Formation and Decay Kinetics of Photochemical H-Transfer in Aromatic Single Crystals from Time Resolve ONP and Optical Methods"


Proceed. of the XXIInd Congr. Amp., Zürich 357 (1984)




J. P. Colpa, B. Prass and D. Stehlik


"Evidence for Tunneling as a Mechanism for a Photochemical Hydrogen Transfer Reaction in Molecular Crystals"


Chem. Phys. Lett. 107, 469 (1984)




W. Siebrand, T. A. Wildman and M. Z. Zgierski


"Golden Rule Treatment of Hydrogen-Transfer Reactions. 2. Applications"


J. Am. Chem. Soc. 106, 4089 (1984)




W. Siebrand, T. A. Wildman and M. Z. Zgierski


"Golden Rule Treatment of Hydrogen-Transfer Reactions. 1. Principles"


J. Am. Chem. Soc. 106, 4083 (1984)




R. E. Gerkin, A. P. Lundstedt and W. J. Reppart


"Structure of Fluorene, C13H10 , at 159K"


Acta Crys C40 1892 (1984)




D. De Vault


"Quantum Mechanical Tunneling in Biological Systems"


Cambridge University Press, London (1984)




H.-M. Vieth


"Kinetics of Photochemical Hydrogen Abstraction in Doped Fluorene Crystals Studied by Timeresolved Optical Nuclear Polarisation"


Chem. Phys. Lett. 103, 124 (1983)




B. Prass, F. Fujara and D. Stehlik


"Kinetics of Photochemical H-Abstraction by 3pp*-Acridine in Fluorene Single Crystals as Studied by Triplet- Triplet Absorption"


Chem. Phys. 81, 175 (1983)




K.-H. Grellmann, H. Weller and E. Tauer


"Tunneleffect on the Kinetics of 2´-Methylacetophenone"


Chem. Phys. Lett. 95, 195 (1983)




W. Siebrand, T. A. Wildman and M. Z. Zgierski


"Temperature Dependence of Hydrogen Tunneling Rate Constants"


Chem. Phys. Lett. 98, 108 (1983)




V. A. Benderskii, P. G. Philippov, Yu. I. Dakhnovskii and A. A. Ovchinnikov


"Low Temperature Chemical Reactions. 1. Models"


Chem. Phys. 67, 301 (1982)




B. Prass


"Tripltt-Triplett-Absorption von Acridin in Fluoren-Einkristallen"


Diploma Thesis, Free University Berlin (1982)




L. I. Trakhtenberg, V. L. Klochikhin and S. Ya. Pshezhetskii


"Theory of Tunnel Transitions of Atoms in Solids"


Chem. Phys. 69, 121 (1982)




L. I. Trakhtenberg, V. L. Klochikhin and S. Ya. Pshezhetskii


"Tunneling of a Hydrogen Atom in Low Temperature Processes"


Chem. Phys. 59, 191 (1981)




B. Prass, F. Fujara, F. Seiff and D. Stehlik


"Triplet-Triplet Absorption Studies in Acridine Doped Fluorene Single Crystals"


J. Luminescence 24/25, 483 (1981)




V. A. Benderskii, V. I. Goldanskii and A. A. Ovchinnikov


"Effect of Molecular Motion on Low-Temperature and Other Anomalously Fast Chemical Reactions in the Solid Phase"


Chem. Phys. Lett. 73, 492 (1980)




J. O. Alben, D. Breece, S. F. Bowne, L. Eisenstein, H. Frauenfelder. D. Good, M. C. Marden, P. P. Moh, L. Reinisch, A. H. Reynolds and K.T. Yue


"Isotope Effect in Molecular Tunneling"


Phys. Rev. Lett. 44, 1157 (1980)




R. P. Bell


"The Tunnel Effect in Chemistry"


Chapman and Hall, London 106 (1980)




V. I. Goldanskii


"Facts and Hypotheses of Molecular Chemical Tunneling"


Nature 279, 109 (1979)




R. A. Marcus


in "Tunneling in Biological Systems"


Academic Press, New York p109 (1979)




B. Chance


in "Tunneling in Biological Systems"


Academic Press, New York p4 (1979)




R. Furrer, M. Heinrich, D. Stehlik and H. Zimmermann


"Radical Pair Formation from Excited States in Doped Aromatic Crystals: EPR Studies of the Guest-Host System Acridine-Fluorene"


Chem. Phys. 36, 27 (1979)




R. L. Hudson, M. Shiotani and F. Williams


"Hydrogen Atom Abstraction by Methyl Radicals in Methanol Glasses at 15-100K: Evidence for a Limiting Rate Constant Below 40 K by Quantum-Mechanical Tunneling"


Chem. Phys. Lett. 48, 193 (1977)




K. Toriyama, K. Nunome and M. Iwasaki


"Electron Spin Resonance Evidence for Tunneling Hydrogen Atom Transfer Reaction at 4.2K in Organic Crystals"


J. Am. Chem. Soc. 99, 5823 (1977)




D. Stehlik


"The Mechanism of Optical Nuclear Polarisation in Molecular Crystals"


in "Excited States"


Academic Press, New York 3, 203 (1977)




V. I. Goldanskii


"Chemical Reactions at Very Low Temperatures"


Ann. Rev. Phys. Chem. 27, 85 (1976)




V. I. Goldanskii , M. D. Frank-Kamenetskii , and I. M. Barkalov


"Quantum Low-Temperature Limit of a Chemical Reaction Rate"


Science 182. 1344 (1973)




R. P. Bell


"The Proton in Chemistry"


Cornell University Press, New York (1973)




A. Bree and R. Zwarich


"Vibrational Assignment of Fluorene from the Infrared and Raman Spectra"


J. Chem. Phys. 51, 912 (1969)




C. Eckart


"The Penetration of a Potential Barrier by Electrons"


Phys. Rev. 35, 1303 (1930)




F. Hund


"Zur Deutung der Molekülspektren. 3 "


Z. Phys. 43, 805 (1927)

Links to authors: C. von Borczyskowski, I. Y. Chan, F. Fujara, B. Prass, D. Stehlik, L. I. Trakhtenberg, H. P. Trommsdorff


H tunneling through barrier.


© 1998-2020 Bernd Prass

17. Abstract: Using time dependent phosphorescence and triplet-triplet absorption studies, the kinetics of the lowest excited triplet state of deuterated acridine has been studied up to room temperature in the hosts fluorene-d8h2 , fluorene-d10 and dibenzofurane. A new high temperature decay channel is observed in the fluorene hosts with a large isotope effect with respect to the 9,9' CH2 group of the host molecule. The relation to the photochemical hydrogen transfer reaction - found also in this system - will be discussed.

J. Luminescence 24/25, 483 (1981)

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23. Abstract: The decay kinetics of the 3pp* state (T) of acridine-d9 in fluorene single crystals is determined as a function of temperature (20 < T < 300 K) via time-resolved triplet-triplet absorption. A series of thermally activated intermolecular decay processes has been identified with a characteristic deuterium isotope effect with respect to the fluorene 9,9' positions. The results can be related consistently to independent kinetic information on the radical-pair product formation by photochemical hydrogen abstraction from fluorene by excited acridine. Comparison to data on 3np*-abstraction reactions in disordered systems elucidates further details of the reaction mechanism.

Chem. Phys. 81, 175 (1983)

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29. Abstract: The temperature dependence of the reaction rate k(T) in the case of the photochemical solid-state reaction of a hydrogen abstraction in doped fluorene single crystals can be described by tunneling through an Eckart potential barrier. Comparison to similarly interpreted hydrogen-transfer reactions are given.

Chem. Phys. Lett. 107, 469 (1984)

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32. Abstract: The reaction rate has been measured in the temperature range 50 < T < 300 K for photochemical H-abstraction by phenazine in its excited triplet state doped in fluorene single crystals. Typical features for a tunneling process like the approach to a constant low-temperature rate, a non-Arrhenius temperature-dependent rate and a substantial deuterium effect are demonstrated. Under specific conditions the nuclear motion promoting the reaction can be assigned as a vibrational oscillator with the fundamental energy of 146 cm-1. Problems and possible ways towards final specification of the reaction-promoting nuclear motion are discussed.

Chem. Phys. Lett. 127, 475 (1986)

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36. Abstract: Data with improved accuracy are presented for the low temperature reaction rates k( T) of the H-tunneling reaction between one specific host neighbor molecule in fluorene single crystals and a photoexcited acridine guest. The constant low temperature reaction rate k0 cannot be separated from the precursor intramolecular decay rate. This does not affect the analysis of the temperature dependent reaction rate, which renders the identification of two distinct thermally excited nuclear fluctuationmodes promoting the H-transfer reaction. The energies are 125(15) and 440(40) cm-1. They agree well with corresponding lines in the Raman spectra of fluorene crystals. For the first time this result offers the possibility to test quantum mechanical reaction mechanisms without the need of averaging over unspecified distributions of nuclear fluctuation modes.

J. Chem. Phys. 88, 191 (1988)

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40. Abstract: Analysis of very accurate measurements of the temperature-dependent part of the H-transfer reaction rate k(T) in acridine-doped fluorene single crystals permits the identification of distinct low-energy nuclear fluctuation modes promoting the reaction. Thus, a form of mode-selective photochemistry has been realized. It is shown that the temperature dependence of the reaction rate can be analyzed in a sequence of functions of the general form z = ln[1 + A exp( -1/x)] where x is a reduced temperature, which is related to the individual energies Ei of the respective reaction promoting modes. The lowest energy reaction promoting mode (125 cm-1) can be well related to the highest energy fluorene lattice mode observed in improved Raman spectra. Its assignment to the ag-libration around the long molecular axis is consistent with a high amplitude modulation along the reaction coordinate. New phosphorescence data remove earlier ambiguities with respect to the existence and contribution of a nonreactive acridine site.

Chem. Phys. 136, 187 (1989)

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51. Abstract: The model calculations of the commented paper are based on our experimental reaction rates for the H-transfer in acridine-doped fluorene single crystals. High experimental accuracy (reported one order of magnitude too low) is crucial to realize that precise rates in a specific low-temperature region provide the most critical test of the theoretical concept used. This has been ignored by the authors with the wrong argument of low accuracy of the experimental data.

Chem. Phys. Lett. 200, 429 (1992)

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56. Abstract: We report a multifaceted investigation of the hydrogen transfer photoreaction in acridine-doped fluorene crystals at higher temperature. The purpose is to elucidate the role of vibrationally assisted tunneling in this reaction system. Raman experiments were conducted at various pressures and 77 K to document the change of vibrational frequency for the promoting mode(s). Upon compression, a line with a large pressure coefficient emerges from under the strong phonon mode at 96.5 cm-1. Through polarization studies under pressure, we have identified it as a molecular butterfly mode of B1 symmetry. We have measured the reaction rate at 150 K in order to examine the effect of a suggested promoting mode at ~440 cm-1. The reaction rate again increases exponentially with pressure, but with a significantly higher pressure coefficient than that at 1.4 and 77 K. Mode patterns based on a recently published (Ref.14) normal coordinate analysis of fluorene are used to help establish the promoting modes for this reaction. This consideration suggests that the 95 and 238 cm-1 modes are likely promoting modes in addition to the 125 cm-1 libration. A computation of the Franck Condon factor for the H-transfer process indicates that a small population of a high overtone of a promoting mode may make a disproportionally large contribution to the reaction rate. This calculation fails to account for the greater pressure coefficient of the reaction rate at higher temperature. Instead, such an increase may come partly from a greater compressibility at higher temperature.

J. Chem. Phys. 103, 2959 (1995)

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60. Abstract: The pressure and temperature dependence of the reaction rate of the photochemical intermolecular H-transfer reaction in acridine-doped fluorene single crystals exhibit all typical features of solid state H-tunneling. Independent Raman data including the pressure dependence have identified three low energy inter- and intramolecular vibrational fluctuations as reaction promoting modes. The mode identification allows a more subtle analysis of the H-transfer reaction rate behavior on the basis of recent theoretical concepts. Surprisingly, the complete data set k(P, T) can be satisfactorily reproduced by an average one mode model with parameters consistent with an average of the parameters calculated for the individual reaction promoting modes.

Ber. Bunsenges. Phys. Chem. 102, 498 (1998)   Look at the poster.

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64. Abstract: We report the pressure effect on the intermolecular deuterium transfer tunneling rate in the acridine-doped fluorene crystal at 77, 150 and 200 K. Similar to the hydrogen transfer, the tunneling rate is exponentially enhanced by pressure.  The pressure slope for this exponential enhancement, however, is found to be more temperature dependent for deuterium than for hydrogen tunneling. The ratio of the pressure coefficients for H and D stands at 2.6 at 77 K, gradually decreases with increasing temperature until it becomes essentially unity at room temperature. An intuitive model based on the mass dependence of the tunneling distance is presented to rationalize these observations.

J. Phys. Chem. 103, 344 (1999)   Look at the manuscript

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69. Abstract: We report a study of the photodimerization of properly arranged anthracene pairs generated by photolysis in a dianthracene crystal at 2 K.  We monitor the progress of the photodimerization reaction by measuring the fluorescence lifetime of the pair excimer state, and we use pressure as an empirical parameter.  Dimerization is too fast to monitor beyond 6 kbar for the normal (protonated) anthracene pairs, and beyond 10 kbar for the perdeutero sample.  The results are interpreted as dimerization through a tunneling mechanism, although evidence of a photophysical retardation was observed. Pressure enhancement of the fluorescence decay rate is exponential. The pressure coefficient for rate enhancement is 0.203 (0.010) natural log units per kbar for the normal sample, and 0.2576 (0.0065) for the perdeuterated sample respectively (with the standard deviation of the mean given in parentheses). The reaction may be formally construed as nanosecond tunneling of a very heavy particle. The origin of the “reverse” deuterium isotope effect is discussed.

J. Chem. Phys. 117, 4419  (2002)   Look at the manuscript

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