ISSN:
1075-4261
Keywords:
Chemistry
;
Analytical Chemistry and Spectroscopy
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Biology
,
Physics
Notes:
Two-dimensional infrared (2D IR) spectroscopy has been shown to be a powerful tool for the analysis of spectra with highly overlapped bands, as often found in IR spectra of biological samples. To date, most 2D IR analyses have focused primarily on intensity changes of the bands under investigation. However, information concerning 2D IR characteristics of bands that change in position or width is sparse. We have thus simulated the effects of frequency and bandwidth changes on 2D IR spectra. In the synchronous plot of a band undergoing a frequency shift, two autopeaks and two crosspeaks are found at the initial and final positions, while the asynchronous plot exhibits two weaker crosspeaks for these positions and a stronger, somewhat elongated feature close to the diagonal. The latter feature is characteristic of a shifting band. Thus, to distinguish a frequency shift in a single band from intensity changes of two overlapped bands it is important to examine the asynchronous plot, since the synchronous plots exhibit comparable characteristics in both cases. A bandwidth change results in a series of crosspeaks. However, when bandwidth changes are coupled with either frequency shifts and/or intensity changes, the effect of the bandwidth change is reduced. Finally, it is shown that the resolution enhancement generally found for the asynchronous plot is accompanied by an error in the positions of the original spectral features as determined from 2D IR peaks. The magnitude of the error increases as the original spectral features approach each other in frequency. © 1996 John Wiley & Sons, Inc.
Additional Material:
5 Ill.
Type of Medium:
Electronic Resource
