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NV <sup>?</sup> –N <sup>+</sup> pair centre in 1b diamond
摘要： With the creation of nitrogen (NV) in 1b diamond it is common to find that the absorption and emission is predominantly of negatively charged NV centres. This occurs because electrons tunnel from the substitutional nitrogen atoms to NV to form NV?–N+ pairs. There can be a small percentage of neutral charge NV0 centres and a linear increase of this percentage can be obtained with optical intensity. Subsequent to excitation it is found that the line width of the NV? zero-phonon has been altered. The alteration arises from a change of the distribution of N+ ions and a modification of the average electric field at the NV? sites. The consequence is a change to the Stark shifts and splittings giving the change of the zero-phonon line (ZPL) width. Exciting the NV? and N0 in the samples results in a significant dependence on excitation wavelength and there is also a dependence on the concentration of the NV? to N+ in the samples. The present investigation involves extensive use of low temperature optical spectroscopy to monitor changes to the absorption and emission spectra particularly the widths of the ZPL. The studies lead to a good understanding of the properties of the NV?–N+ pairs in diamond. There is a critical dependence on pair separation. When the NV?–N+ pair separation is large the properties are as for single sites and a high degree of optically induced spin polarization is attainable. When the separation decreases the emission is reduced, the lifetime shortened and the spin polarization downgraded. With separations of <12 A0 there is even no emission. The deterioration occurs as a consequence of electron tunneling in the excited state from NV? to NV0 and an optical cycle that involves NV0. The number of pairs with the smaller separations and poorer properties will increase with the number of nitrogen impurities and it follows that the degree of spin polarization that can be achieved for an ensemble of NV? in 1b diamond will be determined and limited by the concentration of single substitutional nitrogen. The information will be invaluable for obtaining optimal conditions when ensembles of NV? are required. As well as extensive measurements of the NV? optical ZPL observations of Stark effects associated with the infrared line at 1042 nm and the optically detected magnetic resonance at 2.87 GHz are also reported.
关键词： Stark effect,nitrogen-vacancy,spin polarisation,optical spectroscopy
更新于2025-09-09 09:28:46
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Isophorone-boronate ester: A simple chemosensor for optical detection of fluoride anion
摘要： A highly selective isophorone‐boronate ester based chemosensor, (1), having a dicyanovinyl moiety as a convenient colorimetric probe, has been designed. Different types of anionic analyte such as CH3COO?, Br?, Cl?, ClO4? and HSO4?, PF6? were tested and among them only highly nucleophilic F? anion displayed significant response towards the sensor. Addition of the fluoride anion across the boron atom disrupts the π‐conjugation thereby shifts the absorption wavelength towards the redshift region due to the decrease in the HOMO‐LUMO energy gap and a colour change from yellow to blue is observed under visible light condition. The detection limit of this probe was calculated to be 3.25 × 10?8 M for fluoride anion. The binding constants and the detection limits of the sensor were calculated using absorption titration studies. The silica gel TLC strips dip‐coated by the chemosensor (1) revealed a colour change from yellow to brick red to naked eye.
关键词： chemosensor,boron derivatives,optical Spectroscopy,fluoride anion sensing
更新于2025-09-09 09:28:46
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Ellipsometry - Principles and Techniques for Materials Characterization || Achromatic Ellipsometry: Theory and Applications
摘要： In the present chapter, the theory and some applications of Achromatic Ellipsometry, including transmittance, absorbance, and emission, are presented. The new methodology introduced here comprises the calculation of Stokes parameters using Fourier series analysis. Light polarization was determined by calculating the polarization degree, anisotropy, asymmetry parameters, and rotational and ellipsometry angles. The nematic liquid crystal E7? doped with 4,7-bis{2-[4-(4-decylpiperazin-1-yl)phenyl]ethynyl}-[2,1,3]-benzothiadiazole (5A) within twisted and parallel structures, was used to illustrate the applications for this technique, that has been shown to be an innovative and versatile tool to correlate the photophysics with materials structure.
关键词： ellipsometry,Stokes parameters,optical spectroscopy
更新于2025-09-09 09:28:46
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Simultaneous <i>in vivo</i> optical quantification of key metabolic and vascular endpoints reveals tumor metabolic diversity in murine breast tumor models
摘要： Therapeutically exploiting vascular and metabolic endpoints becomes critical to translational cancer studies because altered vascularity and deregulated metabolism are two important cancer hallmarks. The metabolic and vascular phenotypes of three sibling breast tumor lines with different metastatic potential are investigated in vivo with a newly developed quantitative spectroscopy system. All tumor lines have different metabolic and vascular characteristics compared to normal tissues, and there are strong positive correlations between metabolic (glucose uptake and mitochondrial membrane potential) and vascular (oxygen saturations and hemoglobin concentrations) parameters for metastatic (4T1) tumors but not for micro-metastatic (4T07) and non-metastatic (67NR) tumors. A longitudinal study shows that both vascular and metabolic endpoints of 4T1 tumors increased up to a specific tumor size threshold beyond which these parameters decreased. The synchronous changes between metabolic and vascular parameters, along with the strong positive correlations between these endpoints suggest that 4T1 tumors rely on strong oxidative phosphorylation in addition to glycolysis. This study illustrates the great potential of our optical technique to provide valuable dynamic information about the interplay between the metabolic and vascular status of tumors, with important implications for translational cancer investigations.
关键词： tumor metabolism,Optical spectroscopy,vascular microenvironment,tumor metastasis
更新于2025-09-04 15:30:14
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Raman spectroscopy analysis of new copper‐cysteamine photosensitizer
摘要： Raman spectroscopy and several microstructure analysis techniques have been used to better characterize recently synthesized copper‐cysteamine Cu3Cl(SR)2, where R = CH2CH2NH2. Nanoparticles of this new copper‐cysteamine have been identified as having potential applications in radiation detection and cancer treatment because of the fact that they can be activated by light, X‐rays, ultrasound, and microwave radiation to produce reactive oxygen species. Three samples were grown under different conditions, and their microstructure was examined by using Raman spectroscopy, Fourier transform infrared, scanning electron microscopy, energy dispersive X‐ray scattering, and X‐ray diffraction. The Raman spectroscopy and Fourier transform infrared measurements identify numerous Raman active and infrared absorption bonds with wavenumbers ranging from 200 to 3,500 cm?1. Scanning electron microscopy scans show well‐faceted crystals varying in size from approximately 10 nm to 4 μm, energy dispersive X‐ray scattering measurements identify relative elemental composition (C = 48%, N = 37.5%, S = 5%, Cl = 2.6%, Cu = 7%), X‐ray diffraction data show the crystal plane spacing varies from 0.8454 to 0.8616 nm. The microstructure observed for the three samples is consistent with variations in the growth conditions.
关键词： microstructure,optical spectroscopy of interatomic bonds,cancer treatment,radiation detection,copper‐cysteamine
更新于2025-09-04 15:30:14