Excited-state proton transfer in methanol-doped ice in the presence of KF

The Journal of Physical Chemistry. a
Anna Uritski, Dan Huppert

Abstract

Steady-state and time-resolved emission techniques were employed to study the photoprotolytic cycle of an excited photoacid in ice in the presence of a low concentration of a weak base-like F(-). In previous studies we found that the photoprotolytic cycle in methanol-doped ice (1% mol fraction) is too slow to be observed at temperatures below 190 K. In this study we found that at temperatures below 240 K an additional proton-transfer process occurs in ice doped with 10 mM KF. We attributed this reaction to the creation of a mobile L-defect by F(-) ions. We used a diffusion-assisted reaction model, based on the Debye-Smoluchowski equation, to account for the direct reaction of the L-defect with the excited photoacid at temperatures below T < 240 K. Below 160 K the spectroscopic properties as well as the photoprotolytic cycle change dramatically. We propose that below 160 K the sample enters a new phase. The excited-state proton-transfer (ESPT) process was observed and followed down to a liquid nitrogen temperature of approximately 78 K. In the low-temperature phase the ESPT rate is almost twice as much as at 180 K and the temperature dependence of the rate is very small. The kinetic isotope effect of the ESPT at the low-temperat...Continue Reading

References

Jan 16, 2002·Accounts of Chemical Research·Laren M Tolbert, Kyril M Solntsev
Jul 19, 2003·Science·Matteo RiniErik T J Nibbering
Oct 8, 2005·Science·Omar F MohammedErik T J Nibbering
Feb 14, 2006·The Journal of Physical Chemistry. B·Dominik HegerPetr Klán
Jul 15, 2006·The Journal of Physical Chemistry. a·Noam Agmon
Jul 21, 2006·The Journal of Physical Chemistry. a·Pavel LeidermanDan Huppert
Dec 22, 2006·The Journal of Physical Chemistry. a·Sudip Kumar MondalKankan Bhattacharyya
Dec 22, 2006·The Journal of Physical Chemistry. a·Anna UritskiDan Huppert
May 24, 2007·The Journal of Physical Chemistry. a·Pavel LeidermanDan Huppert
Apr 11, 1952·Science·N Bjerrum
Sep 25, 2007·The Journal of Physical Chemistry. a·Anna Uritski, Dan Huppert

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Citations

Apr 1, 2014·Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy·Yu-Hui LiuSheng-Cheng Lan
May 16, 2013·Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy·Yu-Hui LiuChun-Ran Li
Aug 29, 2009·The Journal of Organic Chemistry·Neta SheferShlomo Rozen

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