Principal Component Analysis Based Two-Dimensional (PCA-2D) Correlation Spectroscopy: PCA Denoising for 2D Correlation Spectroscopy

Jung, Young-Mee Korean Chemical Society 2003 Bulletin of the Korean Chemical Society Vol.24 No.9

Principal component analysis based two-dimensional (PCA-2D) correlation analysis is applied to FTIR spectra of polystyrene/methyl ethyl ketone/toluene solution mixture during the solvent evaporation. Substantial amount of artificial noise were added to the experimental data to demonstrate the practical noise-suppressing benefit of PCA-2D technique. 2D correlation analysis of the reconstructed data matrix from PCA loading vectors and scores successfully extracted only the most important features of synchronicity and asynchronicity without interference from noise or insignificant minor components. 2D correlation spectra constructed with only one principal component yield strictly synchronous response with no discernible a asynchronous features, while those involving at least two or more principal components generated meaningful asynchronous 2D correlation spectra. Deliberate manipulation of the rank of the reconstructed data matrix, by choosing the appropriate number and type of PCs, yields potentially more refined 2D correlation spectra.

Extracting Frequency-Frequency Correlation Function from Two-Dimensional Infrared Spectroscopy: Peak Shift Measurement

곽경원 대한화학회 2012 Bulletin of the Korean Chemical Society Vol.33 No.10

Two-dimensional infrared (2D-IR) spectroscopy can probe the fast structural evolution of molecules under thermal equilibrium. Vibrational frequency fluctuation caused by structural evolution produced the timedependent line shape change in 2D-IR spectrum. A variety of methods has been used to connect the evolution of 2D-IR spectrum with Frequency-Frequency Correlation Function (FFCF), which connects the experimental observables to a molecular level description. Here, a new method to extract FFCF from 2D-IR spectra is described. The experimental observable is the time-dependent frequency shift of maximum peak position in the slice spectrum of 2D-IR, which is taken along the excitation frequency axis. The direct relation between the 2D-IR peak shift and FFCF is proved analytically. Observing the 2D-IR peak shift does not need the full 2DIR spectrum which covers 0-1 and 1-2 bands. Thus data collection time to determine FFCF can be reduced significantly, which helps the detection of transient species.

Extracting Frequency-Frequency Correlation Function from Two-Dimensional Infrared Spectroscopy: Peak Shift Measurement

Kwak, Kyung-Won Korean Chemical Society 2012 Bulletin of the Korean Chemical Society Vol.33 No.10

Two-dimensional infrared (2D-IR) spectroscopy can probe the fast structural evolution of molecules under thermal equilibrium. Vibrational frequency fluctuation caused by structural evolution produced the time-dependent line shape change in 2D-IR spectrum. A variety of methods has been used to connect the evolution of 2D-IR spectrum with Frequency-Frequency Correlation Function (FFCF), which connects the experimental observables to a molecular level description. Here, a new method to extract FFCF from 2D-IR spectra is described. The experimental observable is the time-dependent frequency shift of maximum peak position in the slice spectrum of 2D-IR, which is taken along the excitation frequency axis. The direct relation between the 2D-IR peak shift and FFCF is proved analytically. Observing the 2D-IR peak shift does not need the full 2D-IR spectrum which covers 0-1 and 1-2 bands. Thus data collection time to determine FFCF can be reduced significantly, which helps the detection of transient species.

Exploring the fate and oxidation behaviors of different organic constituents in landfill leachate upon Fenton oxidation processes using EEM-PARAFAC and 2D-COS-FTIR

Aftab, Bilal,Shin, Hyun-Sang,Hur, Jin Elsevier 2018 Journal of hazardous materials Vol.354 No.-

<P><B>Abstract</B></P> <P>In this work, the changes of different organic constituents in landfill leachate were tracked in Fenton oxidation processes with different operation parameters including H<SUB>2</SUB>O<SUB>2</SUB> doses, pH, and the ratios of [H<SUB>2</SUB>O<SUB>2</SUB>]/[Fe] via fluorescence excitation emission matrix – parallel factor analysis (EEM-PARAFAC) and two-dimensional correlation spectroscopy (2D-COS). One tryptophan-like (C1), one fulvic-like (C2), and one humic-like (C3) components were identified in the leachates. The removal behaviors of the individual fluorescent components were dependent upon the operation conditions, suggesting the existence of unique characteristics with respect to the responses to the oxidation mechanisms, which were likely altered by different operation conditions. For all tested conditions, a greater extent of removal was consistently found for C3 versus C1 and C2 except for the relatively high pH ranges (>6.0), in which C2 presented the highest removal rates. 2D-COS combined with synchronous fluorescence spectra exhibited the preferential oxidation sequence in the order of C3 > C1 > C2 with higher H<SUB>2</SUB>O<SUB>2</SUB> doses. 2D-COS coupled with Fourier transform infrared (2D-COS-FTIR) showed that aromatic functional groups were initially oxidized, followed by the removal of carboxylic groups and the formation of inorganic functional groups and aldehyde or ketonic groups. Hetero 2D-COS maps further revealed the close association between the aromatic groups and C3, and between the carboxylic groups and C1. This study utilizing 2D-COS provided new insights into the dynamic behavior of heterogeneous landfill leachate in Fenton oxidation processes under varying operation conditions.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Removal behaviors of different constituents within landfill leachate were tracked. </LI> <LI> Firstly using 2D-COS to explore sequential changes upon Fenton oxidation. </LI> <LI> Preferential removal occurred in the order of C3 > C2 > C1 with higher H<SUB>2</SUB>O<SUB>2</SUB>. </LI> <LI> Changes occurred in the order of aromatic > carboxylic > aldehyde functional groups. </LI> <LI> Hetero 2D-COS revealed association of aromatic and carboxylic groups with C1 and C3. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

2D correlation spectroscopy in characterization of battery materials

정영미,박연주,김예슬 한국공업화학회 2016 한국공업화학회 연구논문 초록집 Vol.2016 No.0

Rechargeable Li-ion batteries, due to their high density, high capacity, light weight, and other relevant properties, have been widely used for energy storage. Improvement of their high capacity, high power density, fast charge-discharge processes as well as safety, therefore, has become a priority. To understand the electrochemical reaction mechanism of battery, 2D correlation spectroscopy (2DCOS) was performed. 2DCOS is the well-established analytical methods, which can provide new molecular level insights for understanding complex systems of interest. 2DCOS has advantages such as enhancement of the spectral resolution, establishment of unambiguous assignments and determination of the sequence of events of the spectral peaks. In this presentation, results of 2DCOS of battery materials will be presented to demonstrate the potential, utility and versatility of this powerful analytical technique for battery study.

2D Correlation Analysis of Spin-Coated Films of Biodegradable P(HB-co-HHx)/PEG Blends

Kim, Min-Kyung,Ryu, Soo-Ryeon,Noda, Isao,Jung, Young-Mee Korean Chemical Society 2011 Bulletin of the Korean Chemical Society Vol.32 No.11

We investigated thermal behavior of spin-coated films of P(HB-co-HHx)/PEG blends by using infraredreflection absorption (IRRAS) spectroscopy and 2D correlation spectroscopy. Based on 2D IRRAS correlation spectra, we could determine the sequence of spectral intensity changes with increasing temperature that PEG band changes first and then a band for crystalline component of P(HB-co-HHx) changes before a band for amorphous component. The intensities of bands for PEG and amorphous P(HB-co-HHx) were changed greatly as PEG weigh % of P(HB-co-HHx)/PEG blends increased. Transition temperatures of P(HB-co-HHx)/PEG blends were successfully determined by 2D gradient mapping method. The transition temperature of spincoated films of 98/2 and 90/10 P(HB-co-HHx)/PEG blends and 80/20 P(HB-co-HHx)/PEG blend determined by 2D gradient map are, respectively, about 137.5 and $132.5^{\circ}C$. Furthermore, P(HB-co-HHx)/PEG blends show an additional transition temperature that have been interpreted in terms of different lamellar thicknesses in spin coated films.

Formation mechanism of BAMLET by 2D Raman correlation analysis

Park, Yeonju,Park, Yujeong,Jin, Sila,Kim, Jung Won,Jung, Young Mee Elsevier 2018 Journal of molecular structure Vol.1171 No.-

<P><B>Abstract</B></P> <P>A partially unfolded bovine α-lactalbumin (ALA) and oleic acid (OA) complex called bovine α-lactalbumin made lethal to tumor cells (BAMLET) is a tumoricidal complex. For the first time, this study investigated the pH-induced formation mechanism of the ALA/OA complex using Raman spectroscopy. For a deeper understanding of the formation mechanism of the ALA/OA complex with decreasing pH, principal component analysis (PCA) and two-dimensional correlation spectroscopy (2D-COS) were applied to pH-dependent Raman spectra of the ALA/OA complex. Based on the results of the PCA and 2D-COS analyses, we successfully elucidated the formation mechanism of the ALA/OA complex at the molecular level. We also confirm that the ALA/OA complex formed below pH 3.0.</P> <P><B>Highlights</B></P> <P> <UL> <LI> For the first time, we investigated the pH-induced formation mechanism of the α-lactalbumin/oleic acid (ALA/OA) complex using Raman spectroscopy. </LI> <LI> We successfully elucidated the formation mechanism of the ALA/OA complex at the molecular level. </LI> <LI> Results of the PCA and 2D-COS analyses showed the ALA/OA complex formed below pH 3.0. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

2D Correlation Analysis of Spin-Coated Films of Biodegradable P(HB-co-HHx)/PEG Blends

김민경,Isao Noda,류수연,정영미 대한화학회 2011 Bulletin of the Korean Chemical Society Vol.32 No.11

We investigated thermal behavior of spin-coated films of P(HB-co-HHx)/PEG blends by using infraredreflection absorption (IRRAS) spectroscopy and 2D correlation spectroscopy. Based on 2D IRRAS correlation spectra, we could determine the sequence of spectral intensity changes with increasing temperature that PEG band changes first and then a band for crystalline component of P(HB-co-HHx) changes before a band for amorphous component. The intensities of bands for PEG and amorphous P(HB-co-HHx) were changed greatly as PEG weigh % of P(HB-co-HHx)/PEG blends increased. Transition temperatures of P(HB-co-HHx)/PEG blends were successfully determined by 2D gradient mapping method. The transition temperature of spincoated films of 98/2 and 90/10 P(HB-co-HHx)/PEG blends and 80/20 P(HB-co-HHx)/PEG blend determined by 2D gradient map are, respectively, about 137.5 and 132.5 ^oC. Furthermore, P(HB-co-HHx)/PEG blends show an additional transition temperature that have been interpreted in terms of different lamellar thicknesses in spin coated films.

Structural symmetry changes in SmB₆ - 2D correlation spectroscopy and principal component analysis

Nguyen, Thi Huyen,Nguyen, Thi Minh Hien,Kang, Boyoun,Cho, Beongki,Park, Yeonju,Jung, Young Mee,Yang, In-Sang Elsevier 2018 Journal of molecular structure Vol.1165 No.-

<P><B>Abstract</B></P> <P>2D correlation analysis (2DCOS) and principal component analysis (PCA) have been performed on temperature-dependent Raman spectra from 12 K to 300 K of SmB<SUB>6</SUB> single crystals grown from Boron with a purity of 99.9% (3N) or 99.9999% (6N). Significant differences in the Raman spectra of SmB<SUB>6</SUB>(3N) and SmB<SUB>6</SUB>(6N) are observed. The Raman active T<SUB>2g</SUB>, E<SUB>g</SUB>, and A<SUB>1g</SUB> modes of SmB<SUB>6</SUB>(3N) are broader and shift to higher wavenumbers compared with those of SmB<SUB>6</SUB>(6N). The results of 2DCOS and PCA on temperature-dependent Raman spectra of SmB<SUB>6</SUB>(3N) and SmB<SUB>6</SUB>(6N) give us further information. We find that all the T<SUB>2g</SUB>, E<SUB>g</SUB>, and A<SUB>1g</SUB> modes of SmB<SUB>6</SUB>(6N) are single bands, while those of SmB<SUB>6</SUB>(3N) show all doublet features. The appearance of multiple bands in Raman vibrational modes of SmB<SUB>6</SUB>(3N) sample implies that the structure of boron octahedra of the SmB<SUB>6</SUB>(3N) has lower symmetry than that of SmB<SUB>6</SUB>(6N). Our findings in 2DCOS and PCA of the Raman spectra strongly support the differences in the behavior of SmB<SUB>6</SUB>(3N) and SmB<SUB>6</SUB>(6N).</P> <P><B>Highlights</B></P> <P> <UL> <LI> The symmetry of the boron octahedra in SmB<SUB>6</SUB> is found to be lowered by small amount of impurities in boron ingredient. </LI> <LI> Raman spectra of SmB<SUB>6</SUB> single crystals strongly depend on the Boron purity. </LI> <LI> 2DCOS and PCA show the multiple bands in the Raman modes of SmB6 made of 99.9% (3N) boron. </LI> </UL> </P>

Thermal Behavior of Langmuir-Blodgett Film of Poly(tert-butyl methacrylate) by Principal Component Analysis Based Two-Dimensional Correlation Spectroscopy

Jung, Young-Mee,Kim, Seung-Bin Korean Chemical Society 2005 Bulletin of the Korean Chemical Society Vol.26 No.12

This paper demonstrates details of thermal behavior of Langmuir-Blodgett (LB) film of poly(tert-butyl methacrylate) (PtBMA) by using the principal component analysis based two-dimensional correlation spectroscopy (PCA2D) through eigenvalue manipulating transformation (EMT). By uniformly lowering the power of a set of eigenvalues associated with the original data, the smaller eigenvalues becomes more prominent and the subtle contribution from minor components is now highlighted much more strongly than the original data. Thus, the subtle difference of thermal behavior of LB film of PtBMA from minor components, which is not readily detectable in the conventional 2D correlation analysis, is much more noticeable than the original data. PCA2D correlation spectra with EMT operation for the temperature-dependent IR spectra of LB film of PtBMA reveal the hidden property of phase transition processes during heating.