Provider: ingentaconnect
Database: ingentaconnect
Content: application/x-research-info-systems
TY - ABST
AU - Hutson, M. Shane
AU - Braiman, Mark S.
TI - Direct Phase Correction of Differential FT-IR Spectra
JO - Applied Spectroscopy
PY - 1998-07-01T00:00:00///
VL - 52
IS - 7
SP - 974
EP - 984
KW - STEP-SCAN DIFFERENCE SPECTROSCOPY DOUBLED ANGLE INTERFEROGRAM SELF-CONVOLUTION PHASE RESOLUTION
N2 - Step-scan transient Fourier transform infrared (FT-IR) difference spectra are often measured in an ac-coupled configuration. The resulting differential intensity spectra contain both positive and negative
bands. This condition poses problems for direct phase correction by the standard Mertz and Forman methods. Restricting the calculated phase angle to the range [-pi/2, pi/2] was previously shown to fix some
of these problems, but we show that the use of a reduced-resolution phase spectrum can produce other artifacts. The effect of reduced resolution is analyzed for a simulated noise-free spectrum and for a
measured transient spectrum of a real photochemical system, bacteriorhodopsin. Examination of these results reveals that the Mertz and Mertz Signed methods can produce spectral bands of reduced magnitude
and unusual band shape, with considerable amounts of intensity remaining along the imaginary axis after phase correction. However, these errors can be eliminated by self-convolution of the measured interferogram,
which doubles all phase angles, prior to smoothing. This procedure removes the potential discontinuities in the phase angle due to sign changes in the differential spectrum. With bacteriorhodopsin, this
doubled-angle method for direct phase correction is able to produce a transient spectrum which closely matches that produced by using a separately measured dc interferogram to calculate the phase angle.
UR - http://www.ingentaconnect.com/content/sas/sas/1998/00000052/00000007/art00011
M3 - doi:10.1366/0003702981944616
UR - http://dx.doi.org/10.1366/0003702981944616
ER -