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Two-dimensional Optical Spectroscopy: Theory and Experiment

Infrared Spectroscopy

  1. Jonggu Jeon,
  2. Sungnam Park,
  3. Minhaeng Cho

Published Online: 15 DEC 2010

DOI: 10.1002/9780470027318.a9117

Encyclopedia of Analytical Chemistry

Encyclopedia of Analytical Chemistry

How to Cite

Jeon, J., Park, S. and Cho, M. 2010. Two-dimensional Optical Spectroscopy: Theory and Experiment. Encyclopedia of Analytical Chemistry. .

Author Information

  1. Korea University, Department of Chemistry, Seoul, Korea

Publication History

  1. Published Online: 15 DEC 2010

Abstract

Two-dimensional (2D) optical spectroscopy, despite its short history, has emerged as a promising technique to study the structure and dynamics of complex molecular systems in condensed phases. This article reviews the basic principles, implementation, and application of this spectroscopic technique. 2D optical spectroscopy employs multiple femtosecond laser pulses in the infrared (IR) or visible frequency range to induce multiple quantum transitions and displays the detected signal in a 2D frequency space. This enables a natural resolution of congested and averaged spectral features often found in condensed-phase 1D spectra. Coupled multichromophore systems exhibit off-diagonal cross peaks reflecting their coupling strengths, which can be monitored in time to extract information on the system dynamics. To provide a perspective on the development of 2D optical spectroscopy, we discuss its brief history. Since 2D spectroscopic features arise from multiple nonlinear optical transitions, their interpretation requires the knowledge of nonlinear response properties of molecular systems. This theoretical background is presented in some detail together with working formulas for two of the most popular techniques, 2D pump-probe and 2D photon echo spectroscopy. Technically, 2D optical spectroscopy has been made possible by the availability of ultrafast femtosecond laser pulses and the spectral interferometric detection method to detect weak signals. The experimental setup of 2D spectrometer is, therefore, described with brief introductions to recent technological developments in instrumentation. Computational methods to simulate 2D optical spectra are also described, which play a vital role in the interpretation of the experimental spectra. General features of 2D spectra and their relations to underlying physical processes are important for proper application of the technique and they are discussed separately. 2D optical spectroscopy has the unique advantage of ultrafast time resolution in addition to spectral resolution in 2D frequency space. It will therefore continue to evolve with technical refinement and provide incisive analytical means to study structure and dynamics of chemical and biological systems.

Keywords:

  • vibrational spectroscopy;
  • two-dimensional spectroscopy;
  • time-resolved spectroscopy;
  • chemical exchange;
  • pump-probe;
  • photon echo;
  • femtosecond laser;
  • spectral interferometry;
  • Fourier-transform spectroscopy