Nanosecond time-resolved step-scan FT-IR spectroscopy in conventional and supercritical fluids using a four-window infrared cell

Xue Z. Sun, Sergei M. Nikiforov, Jixin Yang, Christopher S. Colley, Michael W. George

Research output: Journal PublicationArticlepeer-review

25 Citations (Scopus)

Abstract

Fast time-resolved step-scan FT-IR (s2-FT-IR) has been used to study excited states and reaction intermediates in conventional and supercritical solvents. We have developed a four-port IR cell for s2-FT-IR measurements. The generation of W(CO)5(Xe), following photolysis of W(CO)6 in supercritical Xe, has been used to optimize our s2-FT-IR measurements in supercritical fluids using the four-port IR cell. We have compared a number of different approaches for obtaining transient time-resolved IR (TR-IR) data. The IR diode-laser-based and s2-FT-IR approaches for TR-IR have been compared directly. The kinetic decay of the CpMo(CO)3 (Cp = η5-C5H5) radical in supercritical CO2 has been determined using both TR-IR approaches, and we find no significant difference in signal-to-noise between these techniques for most of our TR-IR kinetic measurements. We have attempted to compare s2-FT-IR to the scanning dispersive TR-IR method by obtaining the infrared spectrum of the triplet excited state of 4-phenylbenzophenone, which has been published previously. The importance of obtaining high spectral resolution s2-FT-IR spectra for reactions in condensed phases is investigated. The IR spectrum of the CpFe(CO)2 radical in n-heptane shows that important information regarding the structure of the radical can only be obtained by performing time-resolved s2-FT-IR experiments at high spectral resolution.

Original languageEnglish
Pages (from-to)31-39
Number of pages9
JournalApplied Spectroscopy
Volume56
Issue number1
DOIs
Publication statusPublished - Jan 2002
Externally publishedYes

Keywords

  • Excited states
  • Reaction intermediates
  • Reaction mechanisms
  • Step-scan FT-IR
  • Time-resolved IR

ASJC Scopus subject areas

  • Instrumentation
  • Spectroscopy

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