Crystal structure, vibrational spectroscopy and optical properties of a one-dimensional organic-inorganic hybrid perovskite of [NH3CH2CH(NH3)CH2]BiCl5.

In this work the crystal structure by single crystal X-ray measurement and optical properties of 1D propane-1,2-diammonium pentachlorobismuthate [NH3CH2CH(NH3)CH3]BiCl5 organic-inorganic hybrid perovskite are presented. It is prepared by mixing ethanolic solution of equimolar ratios (1:1) of its basic components. The title compound crystallized in the noncentrosymmetric orthorhombic space group Pca21 with Z = 8 molecules per unit cell. The unit-cell parameters are a = 19.8403 (7) Å, b = 6.3303 (2) Å, c = 19.0314 (7) Å. The vibrational spectra are studied by Raman and infrared spectroscopy. The optical properties show a strong absorption in the ultraviolet region, the band gap energy Eg is found to be 3.15 eV. Cathodoluminescence measurements are also discussed.

Classification of dental diseases using hyperspectral imaging and laser induced fluorescence.

PURPOSE: Early diagnosis of tooth enamel demineralization, and dentin caries lesions, present a valuable solution to avoid or decrease their deleterious effect. The aim of this study was to design a simple, effective, and non-invasive technique, employing a novel laser wavelength to classify and differentiate between various tooth abnormalities in-vitro, by estimating wavelengths, showing distinctive appearance for each tooth class. METHODS: This study implies a fluorescence hyperspectral imaging system employing a 395-nm laser diode source, irradiating a pre-diagnosed 12 molars and premolars teeth. The obtained reconstructed images were displayed and processed by HSAnalysis2XL, accompanied by a custom made digital, and image signal processing algorithms, revealing the exact wavelengths, characterizing the fluorescence of each tooth pre-diagnosed class. RESULTS: The proposed hyperspectral imaging system was able to discriminate between normal, and abnormal dental classes for the entire specimens. Furthermore, a series of wavelengths, noting each lesion individually were obtained from the spectroscopic hyperspectral output. The root calculus, white spot, dentin caries, and enamel caries have a bright visual appearance at λ3 = 702 nm, λ5 = 771 nm, and λ6 = 798 nm respectively. Consequently, these abnormalities exhibit a dark appearance at λ1 = 421 nm, λ2 = 462 nm, and λ4 = 734 nm. The wavelength selections were confirmed by the grayscale image outcomes. CONCLUSIONS: This study provides a set of wavelengths that can be employed by dentists to diagnose white spot, root calculus, and enamel dentin caries lesions under the irradiation of a new UV-vis laser illumination source without, any hazardous thermal or mechanical effects.

Instant detection and identification of concealed explosive-related compounds: Induced Stokes Raman versus infrared.

The instant detection of explosives and explosive-related compounds has become an urgent priority in recent years for homeland security and counter-terrorism applications. Modern techniques should offer enhancement in selectivity, sensitivity, and standoff distances. Miniaturisation, portability, and field-ruggedisation are crucial requirements. This study reports on instant and standoff identification of concealed explosive-related compounds using customized Raman technique. Stokes Raman spectra of common explosive-related compounds were generated and spectrally resolved to create characteristic finger print spectra. The scattered Raman emissions over the band 400:2000cm-1 were compared to infrared absorption using FTIR. It has been demonstrated that the two vibrational spectroscopic techniques were opposite and completing each other. Molecular vibrations with strong absorption in infrared (those involve strong change in dipole moments) induced weak signals in Raman and vice versa. The tailored Raman offered instant detection, high sensitivity, and standoff detection capabilities. Raman demonstrated characteristic fingerprint spectra with stable baseline and sharp intense peaks. Complete correlations of absorption/scattered signals to certain molecular vibrations were conducted to generate an entire spectroscopic profile of explosive-related compounds. This manuscript shades the light on Raman as one of the prevailing technologies for instantaneous detection of explosive-related compounds.

High-performance near-infrared imaging for breast cancer detection.

We present a method for the noninvasive determination of the size, position, and optical properties of tumors in the human breast. The tumor is first detected by photothermal imaging. It is then sized, located, and optically characterized using designed digital image processing and edge-detection pattern recognition. The method assumes that the tumor is spherical and inhomogeneous and embedded in an otherwise homogeneous tissue. Heat energy is deposited in the tissue by absorption of near-infrared (NIR) Nd:YAG laser radiation, and its subsequent conversion to heat via vibrational relaxation causes a rise in temperature of the tissue. The tumor absorbs and scatters NIR light more strongly than the surrounding healthy tissue. Heat will diffuse through the tissue, causing a rise in temperature of the surrounding tissue. Differentiation between normal and cancerous tissues is determined using IR thermal imaging. Results are presented on a 55-year-old patient with a papillary breast cancer. We found that these results provide the clinician with more detailed information about breast lesions detected by photothermal imaging and thereby enhance its potential for specificity.

High-peak-power operation of a Q-switched Tm3+-doped silica fiber laser operating near 2 microm.

A peak output power of greater than 4.1 kW and a pulse duration at FWHM of 150 ns have been obtained in a Q-switched Tm3+-doped silica fiber laser in the wavelength region near 2 microm when the laser was pumped with a Nd:YAG laser operating at 1.319 microm. An acousto-optic modulator was used as a Q-switching element and operated at repetition rates of as much as 30 kHz. A core diameter of 17 microm was used to increase the laser gain volume, permitting high-pump-power absorption and an output of high pulse energy and peak power. Stimulated Brillouin scattering was directly observed in the output pulse, and as much as 10 orders of stimulated Brillouin scattering was recorded. This is the first report to the authors' knowledge of high-peak-power operation of a Tm3+-fiber laser.