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Search Results: 1 - 10 of 9603 matches for " optical spectroscopy "
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Growth and Characterization of Novel System of Nanoparticles Embedded in Phosphate Glass Matrix  [PDF]
Wageh Swelm, Anwar Higazy, Mohammed Algradee
World Journal of Condensed Matter Physics (WJCMP) , 2011, DOI: 10.4236/wjcmp.2011.12005
Abstract: We present a study of growth of a novel system of CdTe nanoparticles embedded in sodium/lithium-mixed phosphate glass matrix in a strong quantum confinement regime. The prepared systems are characterized by differential thermal analysis, X-ray diffraction, TEM, optical absorption, infrared and Raman Spectroscopy. We have investigated the effect of glass matrix composition and annealing time on the growing of the CdTe semiconductor nanoparticles. We found that the decrease in Na2O content and addition of ZnO to the glass composition is strongly affecting the nanoparticles formation and capping surface of the nanoparticls. On the other hand, we have calculated the size of nanoparticles by effective mass approximation (EMA) and empirical method based on tight binding approximation and found that the calculation based on tight binding approximation are very plausible than that one calculated by EMA.
Single Molecule Applications of Quantum Dots  [PDF]
Thomas E. Rasmussen, Liselotte Jauffred, Jonathan Brewer, Stefan Vogel, Esben R. Torbensen, B. Christoffer Lagerholm, Lene Oddershede, Eva C. Arnspang
Journal of Modern Physics (JMP) , 2013, DOI: 10.4236/jmp.2013.411A2002
Abstract:

Fluorescent nanocrystals composed of semiconductor materials were first introduced for biological applications in the late 1990s. The focus of this review is to give a brief survey of biological applications of quantum dots (QDs) at the single QD sensitivity level. These are described as follows: 1) QD blinking and bleaching statistics, 2) the use of QDs in high speed single particle tracking with a special focus on how to design the biofunctional coatings of QDs which enable specific targeting to single proteins or lipids of interest, 3) a hybrid lipid-DNA analogue binding QDs which allows for tracking single lipids in lipid bilayers, 4) two-photon fluorescence correlation spectroscopy of QDs and 5) optical trapping and excitation of single QDs. In all of these applications, the focus is on the single particle sensitivity level of QDs. The high applicability of QDs in live cell imaging experiments held together with the prospects in localization microscopy and single molecule manipulation experiments gave QDs a promising future in single molecule research.

CW-Dye Laser Spectrometer for Ultrahigh Resolution Spectroscopy: Design and Performance  [PDF]
Hassan El-Kashef
Optics and Photonics Journal (OPJ) , 2014, DOI: 10.4236/opj.2014.48023
Abstract:

This work is devoted to building-up of ultrahigh resolution cw-dye laser spectrometer system. This system used self-frequency-stabilized and temperature-compensated plano-confocal reference cavity. The one-way propagation is achieved using new construction of optical diode. The laser frequency selection and tuning is accomplished using Mach-Zehnder interferometer of free spectral range 42.5 GHz. In combination with computerized tunable radio frequency technique, this system is capable of a resolution of about ±1 KHz. Applications for measuring high lying, weakly occupied metastable states of free atoms (line 548.792 nm of V-51) are investigated to a high degree of accuracy. The results of the constants A and B of the hfs as measured by fluorescence spectroscopy show that A = 160.762 and B = -17.918, while the obtained results for the hfs constants A and B as measured by laser-RF double resonance technique give A = 160.9950 and B = -17.3358.

PAD Spectrometer Based on Wide Tunable Optical Parametric Oscillator for Noninvasive Medical Diagnostics  [PDF]
D. B. Kolker, I. V. Sherstov, A. I. Karapuzikov, A. A. Karapuzikov, A. A. Boyko, M. K.Starikova, N. Yu. Dukhovnikova, V. N. Loconov, M. Yu. Shtyrov, I. B. Miroshnichenko, K. G. Zenov, M. B. Miroshnichenko
Optics and Photonics Journal (OPJ) , 2013, DOI: 10.4236/opj.2013.32B010
Abstract:

The gas analyzer based on optical parametric oscillators (OPO) and laser photo - acoustic spectroscopy is demonstrated. The optical parametric oscillators based on fun – out PPLN and bulk crystal AgGaS2 with a two-pass pumping are developed. Wide tunable OPO is pumped by compact nanosecond Nd: YLF laser. Pulse duration is 5 - 7 ns, maximum pulse energy is 1.5 mJ at a frequency of 100-2000 Hz. OPO lasing threshold is 10 - 16 mJ/cm2 at the spectral range 2.2 - 4 μm for fun – out PPLN OPO and 12 - 20 mJ/cm2 at the spectral range 4 - 7.5 μm for AgGaS2 OPO. Absorption spectra of gaseous mixtures (CH4, C3H8, C2H6, C2H4 and CO2) and human’s breath were studied.

Phantom of Human Adipose Tissue and Studies of Light Propagation and Light Absorption for Parameterization and Evaluation of Noninvasive Optical Fat Measuring Devices  [PDF]
Stefan Hartmann, Matthias Moschall, Oliver Sch?fer, Frank Stüpmann, Ulrich Timm, David Klinger, Jens Kraitl, Hartmut Ewald
Optics and Photonics Journal (OPJ) , 2015, DOI: 10.4236/opj.2015.52005
Abstract: A method for noninvasive determination of fat and water content in the human body is examined. A spatially resolved spectroscopy method is used which can record low intensity near infrared spectra. This novel approach is compared to other methods for the determination of fat and water content. Monte Carlo simulations of light propagation in tissue are shown and the production and characterization of optical phantoms of adipose tissue are investigated.
Spectroscopy: Between Modeling, Simulation and Practical Investigation  [PDF]
Tawfik A. Saleh
Spectral Analysis Review (SAR) , 2014, DOI: 10.4236/sar.2014.21001
Abstract: Spectroscopy
Application of Optical Methods in Blood Studies upon Evaluation of Severity Rate of Diffuse Liver Pathology  [PDF]
Margarita Kruchinina, Mikhail Voevoda, Sergey Peltek, Svetlana Kurilovich, Abdrey Gromov, Vladimir Kruchinin, Sergey Rykhlitsky, Vladimir Volodin, Vladimir Generalov
Journal of Analytical Sciences, Methods and Instrumentation (JASMI) , 2013, DOI: 10.4236/jasmi.2013.32014
Abstract:

Possible early diagnostic application of optical methods (dielectrophoresis, spectral and imaging ellipsometry, Fourier-transform infrared spectroscopy, Raman spectroscopy) in studies of red blood cells and serum of patients with diffuse liver disease with varying degrees of fibrosis has been evaluated. Application of combined optical methods was confirmed to significantly improve the performance of sensitivity, specificity, and accuracy index as well as to achieve the reliable results in diagnosis of both severe fibrosis and slight ulterior liver fibrosis. Identified diagnostic potential of optical methods can be effectively utilized in noninvasive screening evaluation of stages of diffuse liver disease of various geneses.

Chirped Laser Dispersion Spectroscopy for Remote Open-Path Trace-Gas Sensing
Michal Nikodem,Gerard Wysocki
Sensors , 2012, DOI: 10.3390/s121216466
Abstract: In this paper we present a prototype instrument for remote open-path detection of nitrous oxide. The sensor is based on a 4.53 μm quantum cascade laser and uses the chirped laser dispersion spectroscopy (CLaDS) technique for molecular concentration measurements. To the best of our knowledge this is the first demonstration of open-path laser-based trace-gas detection using a molecular dispersion measurement. The prototype sensor achieves a detection limit down to the single-ppbv level and exhibits excellent stability and robustness. The instrument characterization, field deployment performance, and the advantages of applying dispersion sensing to sensitive trace-gas detection in a remote open-path configuration are presented.
Optical heterodyne-Zeeman modulation magnetic rotation spectroscopic technique
Yangqin Chen,Zhiyi Bi,Peipei Cai,Jingxin Ding,Rongjun Wang,Jingjing Lu,Longsheng Ma
Chinese Science Bulletin , 1999, DOI: 10.1007/BF02886342
Abstract: Optical heterodyne detection using 500 MHz phase modulation was combined with the Zeeman modulation-magnetic rotation spectroscopy (ZM-MRS) to form a new spectroscopic technique, which effectively reduced the amplitude fluctuation from laser source and greatly improved the signal-to-noise ratio in the detection of transient molecules.
Joint optical-electrical technique for noninvasive glucose monitoring
Guevara, E.;González, F.J.;
Revista mexicana de física , 2010,
Abstract: in diabetes mellitus, self monitoring of blood glucose is crucial for effective treatment since it can help identify and prevent unwanted periods of hypo- and hyperglycemia; this monitoring procedure usually involves finger-stick testing which is painful to the patient and carries the risk of infection. non-invasive techniques, including impedance and near infrared spectroscopy, have been developed to predict glucose concentration; however, these techniques have not reached the accuracy needed for glucose monitoring. in this work a new concept which involves the combination of two spectroscopic measurements, electrical impedance spectroscopy and near infrared spectroscopy, is developed to decrease the prediction error of single-measurement non-invasive glucose monitoring systems. electrical impedance and near infrared spectroscopy measurements were performed under controlled temperature and humidity conditions on ten non-diabetic volunteers (age 26.1 ± 3.7 years, bmi 25.24 ± 3.67 kg/m2). the results show that all of the values predicted by the joint optical-electrical technique were clinically acceptable and the root mean squared error of prediction, which in this study was compared to a commercial glucose meter, is lower than previously published values for near infrared spectroscopy and impedance spectroscopy done separately.
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