Raman signal optimization based on residual network adaptive focusing.

Due to its high sensitivity and specificity, Micro-Raman spectroscopy has emerged as a vital technique for molecular recognition and identification. As a weakly scattered signal, ensuring the accurate focus of the sample is essential for acquiring high quality Raman spectral signal and its analysis, especially in some complex microenvironments such as intracellular settings. Traditional autofocus methods are often time consuming or necessitate additional hardware, limiting real-time sample observation and device compatibility. Here, we propose an adaptive focusing method based on residual network to realize rapid and accurate focusing on Micro-Raman measurements. Using only a bright field image of the sample acquired on any image plane, we can predict the defocus distance with a residual network trained by Resnet50, in which the focus position is determined by combining the gradient and discrete cosine transform. Further, detailed regional division of the bright field map used for characterizing the height variation of actual sample surface is performed. As a result, a focus prediction map with 1µm accuracy is obtained from a bright field image in 120 ms. Based on this method, we successfully realize Raman signal optimization and the necessary correction of spectral information. This adaptive focusing method based on residual network is beneficial to further enhance the sensitivity and accuracy of Micro-Raman spectroscopy technology, which is of great significance in promoting the wide application of Raman spectroscopy.

A one-dimensional triaqua-europium(III)-1H,3H-benzimidazol-3-ium-5,6-dicarboxyl-ate-sulfate polymeric structure.

In the title coordination polymer, catena-poly[[[triaqua-europium(III)]-bis-(µ-1H,3H-benzimidazol-3-ium-5,6-dicarb-oxyl-ato-κ(3)O(5),O(5'):O(6))-[triaqua-europium(III)]-di-µ-sulfato-κ(3)O:O,O';κ(3)O,O':O'] hexahydrate], [Eu(2)(C(9)H(5)N(2)O(4))(2)(SO(4))(2)(H(2)O)(6)]·6H(2)O}(n), the 1H,3H-benzimidazol-3-ium-5,6-dicarb-oxy-l-ate ligand is protonated at the imidazole group (H(2)bdc). The Eu(III) ion is coordinated by nine O atoms from two H(2)bdc ligands, two sulfate anions and three water mol-ecules, displaying a bicapped trigonal prismatic geometry. The carboxyl-ate groups of the H(2)bdc ligands and the sulfate anions link the Eu(III) ions, forming a chain along [010]. These chains are further connected by N-H⋯O and O-H⋯O hydrogen bonds and π-π inter-actions between the imidazole and benzene rings [centroid-centroid distances = 3.997 (4), 3.829 (4) and 3.573 (4) Å] into a three-dimensional supra-molecular network.

Poly[µ-aqua-diaqua(µ(3)-1H-benzimid-azole-5-carboxylato-κN:O,O')(µ(2)-1H-benzimidazole-5-carboxylato-κN:O:O')-µ(5)-sulfato-µ(4)-sulfato-tri-cadmium].

The asymmetric unit of the title compound, [Cd(3)(C(8)H(5)N(2)O(2))(2)(SO(4))(2)(H(2)O)(3)](n), contains three Cd(II) ions, two sulfate anions, two 1H-benzimidazole-5-carboxyl-ate (H(2)bic) ligands and three coordinated water mol-ecules. One Cd(II) ion is six-coordinated and exhibits a distorted octa-hedral geometry, while the other two Cd(II) ions are seven-coordinated, displaying a distorted penta-gonal-bipyramidal geometry. The Cd(II) ions are bridged by two types of sulfate anions, producing inorganic chains along [100]. These chains are further connected by the H(2)bic ligands, leading to a three-dimensional framework. N-H⋯O and O-H⋯O hydrogen bonds and π-π inter-actions between the imidazole and benzene rings [centroid-centroid distances = 3.953 (2), 3.507 (2), 3.407 (2) and 3.561 (2) Å] further stabilize the crystal structure.