Abstract:
:The involvement of chemical exchange in 2D IR heterodyne echo spectroscopy is characterized through the hydrogen-bond exchange between CH3OH and the CN of CH3CN. The exchange dynamics on the hydrogen-bond potential surfaces associated with different quantum states of the high-frequency CN stretching mode contributes to strong cross peaks between CN groups in two different chemical configurations and provides firm evidence of the hydrogen exchange between them. In analogy with NMR, the chemical exchange is seen in both slow and dynamic regimes. The relative magnitudes of the cross peaks at various population periods measure the picosecond regime time constants for H-bond transfer, whereas the temperature dependences indicate that the activation energy for the exchange from the H-bonded state to the free state is approximately 6.2 kJ.mol(-1). The results suggest that the hydrogen-bond dynamics is very similar in both vibrational quantum states of CN, suggesting that this stretching mode is not strongly coupled to the H-bond breaking reaction coordinate. The likely manifestations of chemical exchange in 2D IR experiments are discussed.
journal_name
Proc Natl Acad Sci U S Aauthors
Kim YS,Hochstrasser RMdoi
10.1073/pnas.0504865102keywords:
subject
Has Abstractpub_date
2005-08-09 00:00:00pages
11185-90issue
32eissn
0027-8424issn
1091-6490pii
0504865102journal_volume
102pub_type
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