Provider: ingentaconnect
Database: ingentaconnect
Content: application/x-research-info-systems
TY - ABST
AU - Myers, Craig W.
AU - Cooper, Stuart L.
TI - Analysis of Some Errors in the Calculation of Orientation Functions for Polymers from Infrared Dichroism Measurements
JO - Applied Spectroscopy
PY - 1994-01-01T00:00:00///
VL - 48
IS - 1
SP - 72
EP - 78
KW - Infrared dichroism
KW - Error analysis
KW - Transition moment angle
KW - Chain conformation distribution
KW - Orientation function
KW - FT-IR
N2 - Infrared dichroism is an important means of characterizing polymer orientation (via the orientation function) which relies upon spectra obtained with polarized infrared radiation. A quantitative analysis is presented here for three different types of errors in the analysis of orientation
via this method. First, the importance of accounting for the conformer distribution within a monomer unit is considered with respect to an example polymer, poly(ethylene oxide). Second, the effects of imperfect polarizer operation ("leakage") are considered in detail for high-precision polarization
optics. It is found that polarizer leakage results in at most ∼4% error in the orientation function at reasonable values for measured absorbances and relatively high frequencies (∼3000 cm^{-1}). Third, since it is common practice to make certain assumptions regarding transition
moment angles in the course of calculating orientation functions, an assessment is made of the effects on the orientation function of erroneously choosing the angle value. The likelihood of adversely affecting the orientation function is found to be lowest near 0° and 90°, increasing
steeply as one approaches the magic angle (54.7°) from either direction.
UR - http://www.ingentaconnect.com/content/sas/sas/1994/00000048/00000001/art00012
M3 - doi:10.1366/0003702944027570
UR - http://dx.doi.org/10.1366/0003702944027570
ER -