Time-resolved infrared spectroscopy application

Hinsmann, P., Frank, J., Svasek, P., Harasek, M., Lendl, B., Design, simulation and application of a new micromixing device for time resolved infrared spectroscopy of chemical reactions in solution, Lab Chip 2001, 1, 16-21. 

Time-resolved infrared spectroscopy (TRIR) has been outstandingly successful in identifying reactive intermediates and excited states of both metal carbonyl [68,69] and organic complexes in solution [70-72]. Some time ago, the potential of TRIR for the elucidation of photochemical reactions in SCFs was demonstrated [73]. TRIR is particularly suited to probe metal carbonyl reactions in SCFs because v(CO) IR bands are relatively narrow so that several different species can be easily detected. Until now, TRIR measurements have largely been performed using tunable IR lasers as the IR source and this has restricted the application of TRIR to the specialist laboratory [68]. However, recent developments in step-scan FTIR spectroscopy promise to open up TRIR to the wider scientific community [74]. 

P. Hinsmann, et al.. Design, Simulation and Application of a New Micromixing Device for Time Resolved Infrared Spectroscopy of Chemical Reactions in Solutions. Lab Chip, 2001, 3, 16-21. 

While the first experiments of time-resolved IR spectroscopy were conducted with pulse durations exceeding 10 ps, the improved performance of laser systems now offers subpicosecond (12) to femtosecond (13-15) pulses in the infrared spectral region. In addition, the pump-probe techniques have been supplemented by applications of higher-order methods, e.g., IR photon echo observations (16). 

As mentioned above, the most informative method to study biochemical reactions would be time-resolved infrared difference spectroscopy. However, because the spectral changes are very small, all techniques require signal averaging over many reaction cycles. This limits application of the techniques to thermally reversible photoreactions. If such systems are in addition stable enough, the photoreaction can be triggered by thousands of flashes. 

Kaw Kawaguchi, K., Hama, Y., Nishida, S. Time resolved Fourier transform infrared spectroscopy Application to pulsed discharges, J. Mol. Spectrosc. 232 (2005) 1—13. 

Another method, which allows the structural characterization and elucidation of the reactivity of transient species using infrared spectroscopy, is to observe them in real time, using fast time-resolved infrared (TRIR) spectroscopy. In this section we shall focus on the application of fast (submillisecond) and ultrafast (subnanosecond) TRIR spectroscopy to coordination compounds, and describe experiments that cannot be performed using conventional infrared spectrometers. 

Time-resolved Fourier transform infrared spectroscopy has been used surprisingly little considering the nuadter of commercial spectrometers that are currently in laboratories and the applicability of this technique to the difficult tine regime from a few is to a few hundred is. One problem with time-resolved Fourier transform spectroscopy and possibly one reason that it has not been more widely used is the stringent reproducibility requirement of the repetitive event in order to avoid artifacts in the spectra( ). When changes occur in the eiaissirr source over the course of a... 

Results of a comprehensive study of the absolute spectral radiance of the infrared emissions from methane—air expins have been reported (Ref 44). The spectral growth of these expanding flames was recorded with a time resolution of one msec in the spectral range 1.7— 5.0 microns. Time resolved spectra were obtained as a function of stoichiometry, nitrogen dilution and Halon dilution. Similar data are also available for coal dust-air explns. Additional applications of rapid scan IR spectroscopy are discussed in Ref 50. In this work, flare spectra (Mk45, LUU-2B and LUU-2B/B) in the 1.7-4.7 and 9—14 micron regions were studied. The Mk-45 and LUU-2B/B showed similar spectral character with Na and C02 emissions superimposed on a gray body continuum, while LUU-2B flares demonstrated variable emittance properties... 

All these advantages explain why today most infrared experiments on biological samples are performed with FT-IR spectrometers. Partial exceptions are time-resolved studies, and the specied techniques employed there are discussed elsewhere in this volume (see [19]). Apart from the book already mentioned on FT-IR spectroscopy in which a special chapter is dedicated to biochemical and biomedical applications including instrumental and sampling aspects, several other useful guides for both the general application of infrared spectroscopy and the more specialized field of biomedical infrared spectroscopy have appeared. " ... 

Synchrotron Infrared spectroscopy has witnessed several important applications in Materials Science over the recent years. This chapter is aimed at highlighting the most recent studies that could inspire new studies from readers. Soft matter (in particular polymer science), catalysis and microscopic ellipsometry have achieved important steps forward in their applications recently, while well-established studies in semiconductors and high pressure studies have generated important results and findings. The field is evolving quickly towards new directions, mainly in the production of intense THz beams that are opening new research directions, in time resolved studies, in fast imaging and in near field infrared microscopy. The recent advances are reported in this chapter. 

The high costs associated with specialist ultrafast laser techniques can make their purchase prohibitive to many university research laboratories. However, centralised national and international research infrastructures hosting a variety of large scale sophisticated laser facilities are available to researchers. In Europe access to these facilities is currently obtained either via successful application to Laser Lab Europe (a European Union Research Initiative) [35] or directly to the research facility. Calls for proposals are launched at least annually and instrument time is allocated to the research on the basis of peer-reviewed evaluation of the proposal. Each facility hosts a variety of exotic techniques, enabling photoactive systems to be probed across a variety of timescales in different dimensions. For example, the STFC Central Laser Facility at the Rutherford Appleton Laboratory (UK) is home to optical tweezers, femtosecond pump-probe spectroscopy, time-resolved stimulated and resonance Raman spectroscopy, time-resolved linear and non-linear infrared transient spectroscopy, to name just a few techniques [36]. 

Slayton, R.M., Anfinrud, P.A. Time-resolved ntid-infrared spectroscopy methods and biological applications. Curr. Opin. StmcL Biol. 7, 717-721 (1997)... 

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