Search query: laser induced fluorescence

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abstract: Abstract Paper based laser induced fluorescence immunodevice for alpha fetoprotein (AFP) detection was developed in this work by using CdTe quantum dots (QDs) embedded silica nanoparticles as the signal enhancement label. A homemade laser induced fluorescence device with two optical fibres was used here for the fluorescence detection. Laser issued by a semiconductor laser light source (405 nm, 1 mW) was exposed to the paper based chip with very lower background through an optical fiber and the fluorescence (542 nm) induced by laser was collected to a photomultiplier tube (PMT) through a glass fiber. The paper based chip was fabricated by the wax printing method and the antibody can be directly immobilized on the plasma treated paper surface. Then CdTe QDs embedded silica nanoparticles with the signal enhancement function was labeled on the signal antibody. After a sandwich type immunoreaction, AFP was linearly detected in the range from 0.001 ng/mL to 20.0 ng/mL with a detection limit of 0.4 pg/mL. Laser induced fluorescence with the homemade device was for the first time applied on the paper based chip with very higher sensitivity. What's more, the proposed strategy opened a promising platform for sensitive monitoring of cancer biomarkers in biological analysis and medical diagnostics.
author_names: Mei Zhao

Huifang Li

Wei Chun Liu

Weiru Chu

Ying Chen
title: Paper based laser induced fluorescence immunodevice combining with CdTe embedded silica nanoparticles signal enhancement strategy
year: 2017

abstract: Cobalt element plays an important role for the properties of magnetism and thermology in steels. In this work, laser induced breakdown spectroscopy combined with laser induced fluorescence (LIBS LIF) was studied to selectively enhance the intensities of Co lines. Two states of Co atoms were resonantly excited by a wavelength tunable laser. LIBS LIF with ground state atom excitation (LIBS LIFG) and LIBS LIF with excited state atom excitation (LIBS LIFE) were compared. The results show that LIBS LIFG has analytical performance with LoD of 0.82mg/g, R(2) of 0.982, RMSECV of 86mg/g, and RE of 9.27% which are much better than conventional LIBS and LIBS LIFE. This work provided LIBS LIFG as a capable approach for determining trace Co element in the steel industry.
author_names: Jiaming Li

Lianbo Guo

Nan Zhao

Xinyan Yang

Rongxing Yi

Kuohu Li

Qingdong Zeng

Xiangyou Li

Xiaoyan Zeng

Yongfeng Lu
title: Determination of cobalt in low alloy steels using laser induced breakdown spectroscopy combined with laser induced fluorescence.
venue: Talanta
year: 2016

abstract: Boron (B) is widely applied in microalloying of metals. As a typical light element, however, determination of boron in alloys with complex matrix spectra is still a challenge for laser induced breakdown spectroscopy (LIBS) due to its weak line intensities in the UV visible NIR range and strong spectral interference from the matrix spectra. In this study, a wavelength tunable laser was used to enhance the intensities of boron lines selectively. The intensities of B I 208.96 nm from boron plasmas were enhanced approximately 3 and 5.8 times while the wavelength tunable laser was tuned to 249.68 and 249.77 nm, respectively. Utilizing the selective enhancement effect, accurate determinations of trace boron in nickel based superalloys and steels were achieved by laser induced breakdown spectroscopy assisted by laser induced fluorescence (LIBS LIF) with limits of detection (LoDs) of 0.9 and 0.5 ppm, respectively. The results demonstrated that LIBS LIF can hopefully be used in boron determinations and has great potential for improving the ability of LIBS to determine light elements in alloys with a complex matrix.
author_names: Changmao Li

Zhong-qi Hao

Zhi Min Zou

Ran Zhou

Jiaming Li

Lianbo Guo

Xiangyou Li

Yongfeng Lu

Xiaoyan Zeng
title: Determinations of trace boron in superalloys and steels using laser induced breakdown spectroscopy assisted with laser induced fluorescence.
venue: Optics express
year: 2016

abstract: In this paper, we present a compact handheld laser induced fluorescence (LIF) detector based on a 450 nm laser diode and quasi confocal optical configuration with a total size of 9.1 x 6.2 x 4.1 cm(3) Since there are few reports on the use of 450 nm laser diode in LIF detection, especially in miniaturized LIF detector, we systematically investigated various optical arrangements suitable for the requirements of 450 nm laser diode and system miniaturization, including focusing lens, filter combination, and pinhole, as well as Raman effect of water at 450 nm excitation wavelength. As the result, the handheld LIF detector integrates the light source (450 nm laser diode) optical circuit module (including a 450 nm band pass filter, a dichroic mirror, a collimating lens, a 525 nm band pass filter, and a 1.0mm aperture) optical detector (miniaturized photomultiplier tube) as well as electronic module (including signal recording, processing and displaying units) This detector is capable of working independently with a cost of ca. $2000 for the whole instrument. The detection limit of the instrument for sodium fluorescein solution is 0.42 nM (S/N=3) The broad applicability of the present system was demonstrated in capillary electrophoresis separation of fluorescein isothiocyanate (FITC) labeled amino acids and in flow cytometry of tumor cells as an on line LIF detector, as well as in droplet array chip analysis as a LIF scanner. We expect such a compact LIF detector could be applied in flow analysis systems as an on line detector, and in field analysis and biosensor analysis as a portable universal LIF detector.
author_names: Xiao-Xia Fang

Han-Yang Li

Pan Fang

Jianzhang Pan

Qun Fang
title: A handheld laser induced fluorescence detector for multiple applications.
venue: Talanta
year: 2016

abstract: This chapter discusses the theory and practical application of laser induced fluorescence (LIF) Fluorescence, generally, is just another name for spontaneous emission. LIF is a two step process: (1) absorption of the laser photon, followed by (2) emission.
author_names: Ronald K Hanson

R Mitchell Spearrin

Christopher S Goldenstein
title: Laser Induced Fluorescence
year: 2016

abstract: The temperature dependence of the fluorescence emission of certain organic dyes such as rhodamine B has been widely utilized for measuring the temperature in liquid flows. Measurements are generally based on two assumptions: The fluorescence signal is proportional to the intensity of the laser excitation, and the temperature sensitivity of the dye is not affected by the laser irradiance. In the ratiometric methods, these assumptions allow justifying that the influence of the laser intensity can be totally eliminated in the intensity ratio of two spectral bands of the fluorescence emission and thus that measurements can be taken with no biases under experimental conditions, where the laser propagation is disturbed by the flow. However, when pulsed lasers are used (mainly in planar LIF measurements) the peak irradiance usually compares or exceeds the saturation intensity of the dyes. The present study assesses the consequences of a saturation of the dye emission on temperature measurements. Tests among fluoresceins and rhodamines reveal that the saturation can be accompanied by a significant loss of temperature sensitivity. The dyes, for which this loss of sensitivity is observed, mainly owe their temperature dependence to the fluorescence quantum yield and have a fluorescence signal decreasing with the temperature. The couple fluorescein/sulforhodamine 640 is finally proposed for an implementation of the ratiometric method, since its relatively high temperature dependence +3 \circ \mathrm{C}$C) is not altered at high laser irradiances. The possibility of measuring instantaneous temperature fields with this pair of dyes using a single laser shot is finally demonstrated on a turbulent heated jet injected into quiescent water.
author_names: William Chaze

Ophelie Caballina

G Castanet

Fabrice Lemoine
title: The saturation of the fluorescence and its consequences for laser induced fluorescence thermometry in liquid flows
year: 2016

abstract: Abstract Downwards co current gas liquid annular flows were studied experimentally and characterized. An advanced optical laser based measurement technique, namely Planar Laser Induced Fluorescence (PLIF) was used for the visualization of the annular flow over a range of liquid Reynolds numbers Re L 306 1 532 and gas Reynolds numbers Re G 0 84 600 Four distinct flow regimes, namely the 'dual wave' 'thick ripple' 'disturbance wave' and 'regular wave' regimes, have been identified based on qualitative information and a consequent quantitative analysis that provided information on the film thickness, interface and wave statistics, and gas entrainment into the liquid film. The mean film thickness data are generally in good agreement with previous studies. Evidence suggests that the turbulent gas phase affects strongly the shape of the interface, and that the mechanism for gas entrainment into the liquid film is strongly reliant on the existence of large amplitude waves.
author_names: Ivan Zadrazil

Omar K Matar

Christos N Markides
title: An experimental characterization of downwards gas liquid annular flow by laser induced fluorescence: Flow regimes and film statistics
year: 2014

abstract: Abstract In this work, laser induced fluorescence (LIF) has been applied to probe PAHs in two atmospheric sooting flames: a premixed flat flame of methane and a Diesel turbulent spray one. Different laser excitation wavelengths have been used. UV excitations at 266 and 355 nm have been operated from the fourth and the third harmonic frequencies of an Nd: YAG laser while visible excitations were emitted by an OPO pumped by the third harmonic of the YAG laser. Because of the different nature of the flames, the recorded fluorescence spectra highlight different spectral properties. The diffusion flame appears to provide a better selectivity to the LIF measurements because of the stratification of the PAHs size classes along the flame height. In the premixed flame, all PAHs size classes spatially coexist making the analysis of LIF measurements more complex. Upon visible excitations, it is highlighted in this paper that PAHs can absorb and fluoresce up to 680 nm. Fluorescence emission spectra are shown to present Stokes and anti Stokes components. Discussion of these non conventional absorption and fluorescence features are provided on the basis of the knowledge of PAH spectroscopy and flame kinetics. Hence, different families of PAHs are successively envisaged and discussed to elucidate the experimental spectra recorded in both flames. It is shown that only a limited number of PAHs are able to lead to such spectral features. From this discussion, it appears that large pericondensed PAHs are unlikely to give rise to such signals. Some other possibilities are therefore discussed which could potentially correspond to the latest fluorescent gaseous species at the origin of the soot formation.
author_names: Salma Bejaoui

X Mercier

Pascale Desgroux

Eric Therssen
title: Laser induced fluorescence spectroscopy of aromatic species produced in atmospheric sooting flames using UV and visible excitation wavelengths
year: 2014

abstract: Abstract. The NASA In Situ Airborne Formaldehyde (ISAF) instrument is a high performance laser based detector for gas phase formaldehyde (HCHO) ISAF uses rotational state specific laser excitation at 353 nm for laser induced fluorescence (LIF) detection of HCHO. A number of features make ISAF ideal for airborne deployment, including (1) a compact, low maintenance fiber laser, (2) a single pass design for stable signal response, (3) a straightforward inlet design, and (4) a stand alone data acquisition system. A full description of the instrument design is given, along with detailed performance characteristics. The accuracy of reported mixing ratios is 10% based on calibration against IR and UV absorption of a primary HCHO standard. Precision at 1 Hz is typically better than 20% above 100 pptv, with uncertainty in the signal background contributing most to variability at low mixing ratios. The 1 Hz detection limit for a signal noise ratio of 2 is 36 pptv for 10 mW of laser power, and the e fold time response at typical sample flow rates is 0.19 s. ISAF has already flown on several field missions and platforms with excellent results.
author_names: Maria Cazorla

Glenn M Wolfe

Steven A Bailey

Andrew K Swanson

H L Arkinson

Thomas F Hanisco
title: A new airborne laser induced fluorescence instrument for in situ detection of formaldehyde throughout the troposphere and lower stratosphere
year: 2014

abstract: This article presents a review of work performed over the past ten years in France, centered on the utilization of laser induced fluorescence (LIF) spectroscopy to diagnose the low pressure magnetized dc discharge of a Hall thruster (HT) The latter is a gridless electric propulsion device in a crossed electric and magnetic field configuration, which is used onboard satellites and space probes for various types of maneuvers. Although the design of a HT is relatively simple, the physical mechanisms that govern thrust generation and efficiency are not yet fully understood. Characterization of the ion and atom velocity distribution function (VDF) appears to be a powerful way to obtain insights into the underlying physics. The VDF of xenon and krypton the most common propellants is therefore locally interrogated by means of LIF on excited levels. In this review emphasis is placed on time averaged and time resolved continuous wave LIF measurements, associated quantities and recent outcomes. Results will be presented concerning a variety of phenomena: velocity vector field structuring, ion population interaction, electric field generation, ion magnetic drift, apparent atom acceleration, interaction of the plasma plume with background gas and low frequency electric field oscillations, to name only a few.
author_names: Stephane Mazouffre
title: Laser induced fluorescence diagnostics of the cross field discharge of Hall thrusters
year: 2012