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Dwuwymiarowa analiza korelacyjna

Czarnecki Mirosław Antoni

Wiadomości Chemiczne

2023

[Z] 77, 7-8

775--800

This review provides fundamental information on theoretical and practical aspects of two-dimensional correlation spectroscopy (2DCOS). At first, is shown a brief development of this method since its introduction by Isao Noda in 1986. In the next part is explained the general idea of 2DCOS, and details of determination of the synchronous and asynchronous spectra from the experimental data. Next section includes comprehensive description of the properties and the rules for interpretation of the 2D correlation spectra. The most common problems with interpretation of 2DCOS spectra, and the ways of improving results of correlation analysis by a proper data pre-treatment are widely discussed. In addition, some of the most important modifications of this method like moving-window analysis and PCMW2D are described. Finally, the usefulness of the power spectra is presented. It has been shown that 2D correlation analysis is a versatile and powerful tool for data analysis and provides information not readily accessible from the original data set.

Thermal and Near-IR Photochemical Generation of Polarons in m-Nitroaniline Crystals. Application of 2D Correlation FT-NIR Spectroscopy

Szostak M., Czarnecki M. A

Polish Journal of Chemistry

2002

Vol. 76 / nr 2-3

419-433

Polarized FT-NIR spectra of m-nitroaniline single crystals in the 4200-10500 cm-1 region, non-irradiated and irradiated at 9700 cm-1, corresponding to the -NH2 stretching second overtone (3 NH s 2 ), were recorded from 300 to 380 K. Direct heating from 325 K to 365 K (phase transition) caused an elevation of the relative background absorbance (A) near 10500 cm-1 . The irradiation by low intensity NIR and a subsequent heating resulted in a different increase of A than in the case of non-irradiated sample. The background elevation is supposed to origin from low-lying electronic transitions of radical ions (polarons) generated by irradiation and heating. Our results indicate that the polarons produced photochemically and thermally are different. The 2D correlation analysis was applied to facilitate the band assignment in the NIR region and to throw more light on thermally induced instabilities in the crystal.