Real-time probing of ion pairing dynamics with 2DIR spectroscopy

Kwang Hee Park, Seung Ryul Choi, Jun Ho Choi, Sungnam Park, Minhaeng Cho

Research output: Contribution to journalArticlepeer-review

39 Citations (Scopus)


Chemical exchange two-dimensional infrared (2DIR) spectroscopy is applied to investigate ion pairing dynamics occurring on picosecond timescales. SeCN- ion is used as a vibrational probe. The SeCN- ion dissolved in N,N-dimethyl formamide (DMF) has a sufficiently long vibrational lifetime and can form a contact ion pair with Li+ ion in DMF. The CN stretch frequency of the contact ion pair is significantly blue-shifted from that of free SeCN- so the free SeCN- ion can be spectrally distinct from the contact ion pair in DMF. Therefore, we were able to directly monitor the ion pairing dynamics of Li+ and SeCN- in real time by using ultrafast 2DIR spectroscopy. As a result, we have determined the dissociation time constant of the LiSeCN contact ion pair to be 420±40 ps.Ion pairing dynamics are probed by using a chemical exchange 2DIR spectroscopic technique in real time (see picture). The dissociation time constant of the LiSeCN contact ion pair in N,N-dimethyl formamide solution is determined to be 420±40 ps.

Original languageEnglish
Pages (from-to)3632-3637
Number of pages6
Issue number17
Publication statusPublished - 2010 Dec


  • Chemical exchange
  • Ion pairing dynamics
  • Ion pairs
  • Ir spectroscopy
  • Vibrational probe

ASJC Scopus subject areas

  • Atomic and Molecular Physics, and Optics
  • Physical and Theoretical Chemistry


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