研究目的
To develop and apply a multivariate curve resolution approach incorporating photochemical hard-models to investigate photochromic systems, specifically to extract quantum yields and study the photochromism of CMTE under continuous monochromatic irradiation.
研究成果
The multivariate curve resolution approach with photochemical hard-models effectively extracts quantum yields and describes the photochemistry of CMTE. Multiset analysis reduces ambiguity and provides reliable results. The study successfully quantifies the photoreactivity of CMTE, revealing quantum yields for various reactions and identifying a new species D formed under 365 nm irradiation. The methodology is applicable to a wide range of photochromic systems.
研究不足
The approach is affected by rotational ambiguity, leading to non-unique solutions even with hard-model constraints. The photochemical model may be incomplete for certain wavelengths (e.g., at 365 nm where additional reactions occur), and the experiments are performed under uncontrolled conditions (e.g., variable oxygen concentration). Computational methods like grid search require careful tolerance settings and may be time-consuming.
1：Experimental Design and Method Selection:
The study uses UV-Visible spectroscopy under continuous monochromatic irradiation. Multivariate curve resolution alternating least squares (MCR-ALS) is employed with photochemical hard-models as constraints to analyze the data. The methodology includes numerical integration of differential equations and grid search algorithms for ambiguity analysis.
2：Sample Selection and Data Sources:
The photochromic compound CMTE (cis-1,2-dicyano-1,2-bis(2,4,5-trimethyl-3-thienyl)ethene) is used, with samples prepared from commercially available CMTE. Data are collected from experiments under irradiation at wavelengths of 405 nm, 365 nm, and 546 nm, starting from pure isomers A, B, or C.
3：List of Experimental Equipment and Materials:
Equipment includes a Hg/Xe lamp (200 W, Hamamatsu Lightningcure LC6) with narrow-band interference filters, a CCD camera, and a polychromator. Materials include CMTE isomers in chloroform solution.
4：Experimental Procedures and Operational Workflow:
UV-Visible absorption spectra are recorded every 0.7 s from 275 to 625 nm under continuous irradiation. Different experiments are conducted by varying the initial state and irradiation wavelength. Data analysis involves MCR-ALS with constraints such as non-negativity and closure, and hard-modelling for kinetic fitting.
5：7 s from 275 to 625 nm under continuous irradiation. Different experiments are conducted by varying the initial state and irradiation wavelength. Data analysis involves MCR-ALS with constraints such as non-negativity and closure, and hard-modelling for kinetic fitting.
Data Analysis Methods:
5. Data Analysis Methods: Data are analyzed using MCR-ALS with soft and hard constraints. Ambiguity is evaluated using grid search algorithms in MATLAB. Lack of fit and other error indicators are used to assess the quality of the decomposition.
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