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A Vibrational Rotational Strength of Extraordinary Intensity. Azidomethemoglobin A

  • Curtis Marcott
  • Henry A. Havel
  • Bo Hedlund
  • John Overend
  • Albert Moscowitz
Part of the NATO Advanced Study Institutes Series book series (ASIC, volume 48)

Abstract

The asymmetric stretching vibration of the N3 - group in azidomethemoglobin A (azidometHb A) exhibits a vibrational circular dichroism (VCD) band (Fig. 1) of extraordinary and unprecedented intensity. Its rotational strength is three orders of magnitude greater than any heretofore noted. Integration of the VCD band gives a vibrational rotational strength (per tetramer) of 3 × 10 -40 (esu cm)2, a value typical for the electronic rotational strengths associated with the n → π* transition in saturated ketones.

Keywords

Lone Pair Infrared Transmission Vibrational Circular Dichroism Rotational Strength Infrared Transmission Spectrum 
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References and Notes

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    We have replaced the homemade germanium modulator described in Ref. [1] with a commercial 57 kHz CaF2 photoelastic modulator (Hinds International). The signal processing electronics have also been modified and are now similar to that described by Nafie, et al. [3]. The PAR model HR-8 lock-in amplifier has been replaced by two lock-ins: an ORTEC model 9503 followed by a PAR model 186A. Unlike the electronics described in Ref. [3], we do not have a normalization circuit, but rather divide the output of the PAR 186A by the output of the PAR model 220 lock-in [1] with an ORTEC model 5047 ratiometer. These modifications have resulted in a considerable flattening of the baseline and a significant improvement in signal-to-noise ratio over earlier spectra. See for example, H. Sugeta, C. Marcott, T. R. Faulkner, J. Overend, and A. Moscowitz, Chem. Phys. Lett., 40, 397 (1976).CrossRefGoogle Scholar
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    S. McCoy and W. S. Caughy, Biochemistry, 9, 2387 (1970).CrossRefGoogle Scholar

Copyright information

© Springer Science+Business Media Dordrecht 1979

Authors and Affiliations

  • Curtis Marcott
    • 1
  • Henry A. Havel
    • 1
  • Bo Hedlund
    • 1
  • John Overend
    • 1
  • Albert Moscowitz
    • 1
  1. 1.Department of Chemistry and Department of Laboratory Medicine and PathologyUniversity of MinnesotaMinneapolisUSA

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