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Phase‐specific Raman analysis of n ‐alkane melting by moving‐window two‐dimensional correlation spectroscopy
Author(s) -
Jin Ying,
Kotula Anthony P.,
Hight Walker Angela R.,
Migler Kalman B.,
Lee Young Jong
Publication year - 2016
Publication title -
journal of raman spectroscopy
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.748
H-Index - 110
eISSN - 1097-4555
pISSN - 0377-0486
DOI - 10.1002/jrs.4967
Subject(s) - raman spectroscopy , orthorhombic crystal system , analytical chemistry (journal) , phase (matter) , phase transition , chemistry , two dimensional nuclear magnetic resonance spectroscopy , amorphous solid , materials science , crystallography , thermodynamics , crystal structure , organic chemistry , optics , stereochemistry , physics
We use moving‐window two‐dimensional correlation spectroscopy (MW‐2DCOS) for phase‐specific Raman analysis of the n ‐alkane (C 21 H 44 ) during melting from the crystalline solid phase to the intermediate rotator phase and to the amorphous molten phase. In MW‐2DCOS, individual peak‐to‐peak correlation analysis within a small subset of spectra provides both temperature‐resolved and spectrally disentangled Raman assignments conducive to understanding phase‐specific molecular interactions and chain configurations. We demonstrate that autocorrelation MW‐2DCOS can determine the phase transition temperatures with a higher resolving power than commonly used analysis methods including individual peak intensity analysis or principal component analysis. Besides the enhanced temperature resolving power, we demonstrate that asynchronous 2DCOS near the orthorhombic‐to‐rotator transition temperature can spectrally resolve the two overlapping peaks embedded in the Raman CH 2 twisting band in the orthorhombic phase, which had been only predicted but not observed because of thermal broadening near the melting temperature. Published 2016. This article is a U.S. Government work and is in the public domain in the USA.