To address the challenge of nonphase matching in many infrared (IR) nonlinear optical (NLO) materials, despite having substantial NLO coefficients, we present a new strategy for realizing phase matching (PM) in IR NLO materials by manipulating the fractal dimension (FD) of covalent motifs. As a representative demonstration, we select a salt-inclusion chalcogenide system and validate its efficacy. Consequently, we successfully synthesized two new chalcogenides, denoted as K-2[K4Cl][Ga5Sn7S24] (1) and [Na4I][Ga9S15] (2). The latter exhibits PM, while the former does not, primarily attributed to their markedly different FD values of the electron localization function map, resulting in distinct optical anisotropy. Compounds 1 and 2 demonstrate enhanced IR NLO efficiency, measuring 0.25 and 0.70 times that of AgGaS2 at 1910 nm, respectively. Notably, compound 2 features a wide band gap of 3.10 eV and a substantial-high laser-induced damage threshold (LIDT) of 93.15 MW cm(-2)@1064 nm (9.6 x AgGaS2). This work illuminates the exploration of new PM IR NLO materials derived from nonphase matching counterparts.

Rare-earth infrared nonlinear optical (IR NLO) compounds have garnered significant attention due to their abundant electronic structures. However, their NLO efficiency has been relatively modest, attributed to the localization of valence electron shells in rare-earth metals. Traditional design strategies for IR NLO materials have predominantly focused on MQ(4) (M = metal, Q = S or Se) tetrahedra, with limited exploration of MQ(6) octahedra. We introduce a novel approach to enhance NLO effects by incorporating distorted mixed anionic octahedral M(S/X)(6) groups. To illustrate this strategy, we undertake structure modification and optimization of IR NLO performance using the Y-Ga-Ge-S system as an example. The synthesis of a new rare-earth chalcogenide, Y6Ga2GeS14 (1), serves as a foundation. Further halogen atom substitution yields Y6Ga4.2S13.6Cl3.4 (2), Y6Ga2.83Ge2S16.75Cl (3), and Y6Ga2.83Ge2S16.5Br1.5 (4). All compounds demonstrate remarkable NLO performance, including moderate NLO coefficients (0.17-0.70 x AgGaS2), large laser-induced damage thresholds (LIDTs) (3.78-6.19 x AgGaS2), and a broader transmission range (0.5-14.9 mu m). The incremental enhancement of NLO efficiency in compounds 1-4 can be attributed to symmetry breaking induced by halogen atom substitution and increased distortion of the octahedral M(S/X)(6) motifs in their structures, validating the effectiveness of our strategy. Notably, this strategy concurrently increases the band gap and LIDT, overcoming the NLO-LIDT incompatibility, being strikingly different from other reported approaches. This work provides new insights into optimizing the NLO performance of rare-earth IR NLO compounds through the modulation of octahedral motifs.

As a label-free, nondestructive, and in situ detection method, Raman spectroscopy analysis of single cells has potential application value in biomedical fields such as cancer diagnosis. In this study, the Raman spectral characteristics of nucleophosmin (NPM1)-mutant acute myeloid leukemia (AML) cells and nonmutated AML cells were investigated, and the reasons for the differences in spectral peaks were explained in combination with transcriptomic analysis. Raman spectra of two AML cell lines without NPM1 mutation (THP-1 and HL-60) and the OCI-AML3 cell line carrying the NPM1 mutant gene were cultured and collected experimentally. It was found that the average Raman spectra of NPM1 mutant and nonmutated cells had intensity differences in multiple peaks corresponding to chondroitin sulfate (CS), nucleic acid, protein, and other molecules. The differentially expressed genes were identified by quantitative analysis of the gene expression matrix of the two types of cells, and their roles in the regulation of CS proteoglycan and protein synthesis were analyzed. The results showed that the differences between the two types of cells expressed by the single-cell Raman spectral information were consistent with the differences in transcriptional profiles. This research could advance the application of Raman spectroscopy in cancer cell typing.

Acute myeloid leukemia (AML) is a malignant clonal blood disease of hematopoietic stem cells with poor prognosis. Traditional diagnosis of AML depends on the morphology, immunology, cytogenetics, and molecular biology (MICM) classification. As a rapid, label-free and non-destructive detection method, Raman spectroscopy can characterize the molecular information in the biochemical process at the molecular level through peak position, intensity and other information. In this paper, we collected leukemic blast cells from 19 AML patients. Firstly, it was proved that with the help of multivariate analysis methods such as principal component analysis-linear discriminant analysis (PCA-LDA) and multivariate curve resolution-alternating least squares (MCR-ALS), Raman spectroscopy could effectively distinguish AML cells from normal leukocytes, and the accuracy rate was up to 96.71%. The results showed that compared with normal leukocytes, multiple components of information decomposed by the AML spectrum represented abnormal alterations in proteins, nucleic acids, lipids and carbohydrates in leukemia cells. Secondly, the same procedure was used to further detect different types of AML and found that Raman spectroscopy could distinguish AML cells with FMS-like tyrosine kinase 3-Internal Tandem Duplications (FLT3-ITD) mutations or not, and there were differences in spectral characteristics corresponding to nucleic acids and proteins (amino acids). The above results revealed that Raman spectroscopy has great potential for clinical diagnosis and mechanistic study of AML.