{"title":"层状碘化铅量子点的光谱学和原子力显微镜化学和尺寸表征","authors":"R. Mu, Y. S. Tung, A. Ueda, D. O. Henderson","doi":"10.1021/jp960605a","DOIUrl":null,"url":null,"abstract":"<p >Lead iodide (PbI<sub>2</sub>) clusters were synthesized from the chemical reaction of NaI (or KI) with Pb(NO<sub>3</sub>)<sub>2</sub> in H<sub>2</sub>O, D<sub>2</sub>O, CH<sub>3</sub>OH, and C<sub>3</sub>H<sub>7</sub>OH solvents. The observation of absorption features between the 550 and 350 nm region obtained with an integrating sphere strongly suggests PbI<sub>2</sub> quantum dot formation in solution. Comparison of spectra of PbI<sub>2</sub> clusters in solution with PbI<sub>2</sub> clusters formed by impregnation of PbI<sub>2</sub> in four different pore-sized porous silica substrates indicates that the PbI<sub>2</sub> cluster size in solution is less than 2.5 nm in the lateral dimension. Atomic force microscopy (AFM) measurements of PbI<sub>2</sub> solutions deposited on mica and highly oriented pyrolytic graphite surfaces indicate that the clusters are single layered. The measured height is 1.0 ± 0.1 nm, which is ~0.3 nm larger than the layer thickness observed for the bulk materials. The swollen layer thickness can be attributed to the intralayer contraction from the strong lateral interaction among PbI<sub>2</sub> molecules, which is supported by <i>ab initio</i> calculations. Raman scattering measurements of the LO and TO modes of PbI<sub>2</sub> in bulk and in the confined state were also conducted in 50?150 cm<sup>-1</sup> region. Three bands observed at 74, 96, and 116 cm<sup>-1</sup> for the confined materials are assigned to the TO<sub>2</sub>, LO<sub>2</sub>, and LO<sub>1</sub> modes, respectively. The relatively small red shift in the LO modes for PbI<sub>2</sub> in the porous hosts may be caused by the surface phonon of PbI<sub>2</sub> nanoparticles confined in the porous silica. </p>","PeriodicalId":58,"journal":{"name":"The Journal of Physical Chemistry ","volume":null,"pages":null},"PeriodicalIF":2.7810,"publicationDate":"1996-12-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1021/jp960605a","citationCount":"44","resultStr":"{\"title\":\"Chemical and Size Characterization of Layered Lead Iodide Quantum Dots via Optical Spectroscopy and Atomic Force Microscopy\",\"authors\":\"R. Mu, Y. S. Tung, A. Ueda, D. O. Henderson\",\"doi\":\"10.1021/jp960605a\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"<p >Lead iodide (PbI<sub>2</sub>) clusters were synthesized from the chemical reaction of NaI (or KI) with Pb(NO<sub>3</sub>)<sub>2</sub> in H<sub>2</sub>O, D<sub>2</sub>O, CH<sub>3</sub>OH, and C<sub>3</sub>H<sub>7</sub>OH solvents. The observation of absorption features between the 550 and 350 nm region obtained with an integrating sphere strongly suggests PbI<sub>2</sub> quantum dot formation in solution. Comparison of spectra of PbI<sub>2</sub> clusters in solution with PbI<sub>2</sub> clusters formed by impregnation of PbI<sub>2</sub> in four different pore-sized porous silica substrates indicates that the PbI<sub>2</sub> cluster size in solution is less than 2.5 nm in the lateral dimension. Atomic force microscopy (AFM) measurements of PbI<sub>2</sub> solutions deposited on mica and highly oriented pyrolytic graphite surfaces indicate that the clusters are single layered. The measured height is 1.0 ± 0.1 nm, which is ~0.3 nm larger than the layer thickness observed for the bulk materials. The swollen layer thickness can be attributed to the intralayer contraction from the strong lateral interaction among PbI<sub>2</sub> molecules, which is supported by <i>ab initio</i> calculations. Raman scattering measurements of the LO and TO modes of PbI<sub>2</sub> in bulk and in the confined state were also conducted in 50?150 cm<sup>-1</sup> region. Three bands observed at 74, 96, and 116 cm<sup>-1</sup> for the confined materials are assigned to the TO<sub>2</sub>, LO<sub>2</sub>, and LO<sub>1</sub> modes, respectively. The relatively small red shift in the LO modes for PbI<sub>2</sub> in the porous hosts may be caused by the surface phonon of PbI<sub>2</sub> nanoparticles confined in the porous silica. </p>\",\"PeriodicalId\":58,\"journal\":{\"name\":\"The Journal of Physical Chemistry \",\"volume\":null,\"pages\":null},\"PeriodicalIF\":2.7810,\"publicationDate\":\"1996-12-19\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"https://sci-hub-pdf.com/10.1021/jp960605a\",\"citationCount\":\"44\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"The Journal of Physical Chemistry \",\"FirstCategoryId\":\"1\",\"ListUrlMain\":\"https://pubs.acs.org/doi/10.1021/jp960605a\",\"RegionNum\":0,\"RegionCategory\":null,\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"\",\"JCRName\":\"\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"The Journal of Physical Chemistry ","FirstCategoryId":"1","ListUrlMain":"https://pubs.acs.org/doi/10.1021/jp960605a","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"","JCRName":"","Score":null,"Total":0}
Chemical and Size Characterization of Layered Lead Iodide Quantum Dots via Optical Spectroscopy and Atomic Force Microscopy
Lead iodide (PbI2) clusters were synthesized from the chemical reaction of NaI (or KI) with Pb(NO3)2 in H2O, D2O, CH3OH, and C3H7OH solvents. The observation of absorption features between the 550 and 350 nm region obtained with an integrating sphere strongly suggests PbI2 quantum dot formation in solution. Comparison of spectra of PbI2 clusters in solution with PbI2 clusters formed by impregnation of PbI2 in four different pore-sized porous silica substrates indicates that the PbI2 cluster size in solution is less than 2.5 nm in the lateral dimension. Atomic force microscopy (AFM) measurements of PbI2 solutions deposited on mica and highly oriented pyrolytic graphite surfaces indicate that the clusters are single layered. The measured height is 1.0 ± 0.1 nm, which is ~0.3 nm larger than the layer thickness observed for the bulk materials. The swollen layer thickness can be attributed to the intralayer contraction from the strong lateral interaction among PbI2 molecules, which is supported by ab initio calculations. Raman scattering measurements of the LO and TO modes of PbI2 in bulk and in the confined state were also conducted in 50?150 cm-1 region. Three bands observed at 74, 96, and 116 cm-1 for the confined materials are assigned to the TO2, LO2, and LO1 modes, respectively. The relatively small red shift in the LO modes for PbI2 in the porous hosts may be caused by the surface phonon of PbI2 nanoparticles confined in the porous silica.