Use Of LiF Research Articles

Can providing daily iron-fortified lunches to school-going children living in an impoverished Guatemalan community improve iron status?

Background Iron deficiency anemia (IDA) remains one of the most common diet-related micronutrient deficiency disorders in the world. Although iron supplementation can effectively improve iron status, it is often a short-term solution to this endemic, chronic health problem. Lucky Iron Fish® (LIF) offers a novel, long-term approach to treat IDA that can be easily utilized in regions of the world where IDA is most prevalent. While the beneficial use of LIF for household preparation of meals has been demonstrated, its use in quantity food production has not been investigated. The purpose of this study was to develop methodology for large-scale iron fortification of cooking water and to assess changes in hemoglobin and hematocrit values in school-going children following 8 months of receiving iron-fortified school lunches prepared with LIF. Methods Laboratory studies were conducted to develop the protocol to prepare iron fortification of cooking water using LIF. Study participants were school-going children from economically, disadvantaged families attending private schools in Jocotenango, Guatemala. Baseline measures (weight, height, hemoglobin, and hematocrit) were taken at the start and completion of the academic calendar. The sample was divided into quintiles based on pre-hemoglobin and hematocrit values where quintile 1 had the lowest baseline hemoglobin and hematocrit values and quintile 5 had the highest baseline hemoglobin and hematocrit values. Paired t-tests were used to determine if there were overall significant pre- and post-differences in iron status values by quintile groupings. Results A total of 286 (77%) of children between the ages of 5 – 16 (y) completed the study. Post- hemoglobin values were significantly higher than pre-hemoglobin values for those in quintile 1, whereas post-hematocrit values significantly increased for quintiles 1 and 2. Conclusions Study results suggest that LIF can be used to prepare large quantities of food and that regular consumption of iron-fortified school lunches can improve iron status in children with marginal status. Equally important is the finding that iron-fortified meals do not negatively impact those with healthy iron values.

Synthesis of 3-Borylated Pyrrolidines by 1,3-Dipolar Cycloaddition of Alkenyl Boronates and Azomethine Ylide.

A scalable and efficient process for the preparation of 3-borylated pyrrolidines by 1,3-dipolar cycloaddition of N-benzyl azomethine ylide generated in situ has been developed. The optimized method included the use of LiF in DMSO at 110 °C and was suitable for α-mono-, α,β-di-, and α,β,β-trialkyl-, β,β-(hetera)cycloalkylidene-, CO2 Et-, as well as most β-(het)aryl-substituted alkenyl boropinacolates. The 1,3-dipolar reaction proceeded on a multigram scale providing 3-borylated pyrrolidines with diverse substitution patterns (including fused and spirocyclic ones) in a diastereoselective manner. The Pd(OH)2 -mediated N-debenzylation of pyrrolidine hydrochlorides was successfully performed to give the corresponding bifunctional building blocks on an up to 130 g scale, thus providing a substantial expansion of the synthetic and medicinal chemist's toolbox. Other reactions included the preparation of trifluoroborates, Zweifel-Aggarwal sp3 -sp2 coupling, and oxidative deborylation as an example of C-heteroatom bond formation.

SEARCH FOR EXPERIMENTAL EVIDENCE OF DOSE-RATE AND WALL SCATTERING EFFECTS IN THE THERMOLUMINESCENCE RESPONSE OF LIF:MG,TI (TLD-100).

An experimental investigation into the possibility of dose-rate effects and wall scatter in the thermoluminescent response of LiF:Mg,Ti (TLD-100) was carried out. The investigation was motivated by theoretical simulations predicting the possible presence of dose-rate effects coupled with the lack of detailed experimental studies. The dose rate was varied by changing the source to sample distance, by the use of attenuators, sources of 137Cs of various activities, filtration and the construction of identical geometrical irradiators of Teflon and stainless steel. Four levels of dose in the linear dose response region were studied at 10-2 Gy, 1.5 × 10-2 Gy, 0.1 Gy and 0.5 Gy to avoid complications in interpretation due to supralinearity above 1 Gy. At the dose of 1.5 × 10-2 Gy, the dose rate was varied by five orders of magnitude from 4.9 × 10-3 Gy s-1 to 4.9 × 10-8 Gy s-1. At the other levels of dose, a one to two orders of magnitude in dose rate was achieved. Within the measurement uncertainty of 5-10%, no dose-rate effects were observed in any of the experimental measurements and no changes in the shape of the glow curve were observed. The maximum wall scatter effect (Teflon to stainless steel) was measured at ~8% within the experimental uncertainty and well below expectations. The results are encouraging with respect to the accurate and reproducible use of LiF:Mg,Ti under various experimental conditions of irradiation.

Development of Metal-Supported Proton-Conducting Solid Oxide Cells Via Co-Sintering

Use of proton conducting electrolytes in solid oxide fuel cells (SOFCs) and electrolysis cells (SOECs) enables efficient operation at lower temperatures, reducing thermal stress and allowing the use of less expensive stack materials and balance-of-plant components. Transport of protons across the electrolyte offers other advantages: for electrolysis, pure hydrogen is produced so steam does not need to be removed; for fuel cell operation, extraction of hydrogen from the anode through the electrolyte drives fuel decomposition or reforming reactions. Proton conducting oxide electrolyte materials could potentially lower the operating temperature of metal-supported solid oxide cells (MS-SOCs) to the intermediate range 400 to 600 °C. The metal substrate provides the advantages such as high thermal and redox cycling tolerance, low-cost of structural materials, and mechanical ruggedness.In this work, co-sintering fabrication of metal-supported proton conducting solid oxide cells using BaZr1-x-yCexYyO3-δ (BZCY) is developed. BZCY ceramics are sintered in reducing environment supported on stainless steel metal support. Critical challenges for this fabrication approach include: contamination of the electrolyte with Si and Cr from the metal support, incomplete electrolyte sintering, and evaporation of Ba from the electrolyte. Lowering the sintering temperature to 1350°C alleviates these challenges. The use of LiF and Mn-oxide as sintering aids achieve electrolyte densification at this low temperature. Nevertheless, shrinkage matching of the stainless steel and ceramic layers during sintering is very challenging. Various efforts will be discussed, including optimization of the ceramic sintering aid loading, impact of metal particle size, and thermal manipulation of the ceramic powder surface. Successful co-sintering of a symmetric cell is achieved.

On the Role of LiF in Organic Optoelectronics

Organic optoelectronic device behaviour is heavily dependent on interfacial effects due to the device architecture and thickness. Interfaces between the inorganic electrodes and the active organic layers play a defining role in the all of the electronic and stability processes that occur in organic light emitting diodes (OLEDs) and organic solar cells (OPVs). Amongst the many interlayers introduced at these interfaces to improve charge carrier movement and stability, LiF has proven to be the most successful and it is almost ubiquitous in all organic semiconductor devices. Implemented at both top and bottom contact interfaces, doped into the charge transporting layers, and used as encapsulants, LiF has played major roles in device performance and lifetime. This review highlights the use of LiF at both top and bottom contacts in organic optoelectronics, discusses the various mechanisms proposed for the utility of LiF at each interface, and explores its impact on device lifetimes. From examples relating to charge carrier flow, interfacial electronic level modification, and interfacial stability, a comprehensive picture of the role of LiF in organic devices can be formed. This review begins with a brief overview of the role of the interface in OLEDs and OPVs, and the general properties of LiF. Then, it discusses the implementation of LiF at the top contact electrode interface, followed by the bottom substrate contact electrode, examining both performance and degradation effects in both cases.

Mechanisms of LiF Interlayer Enhancements of Perovskite Light-Emitting Diodes.

The use of LiF as a thin interlayer between the electron transport layer and cathode has played a pivotal role in remarkable advances in perovskite LEDs (PeLEDs); however, the mechanism behind the effect of LiF remains to be fully understood. Here, we report a combined experimental and computational study, from which we ascribe the benefits of a LiF interlayer to the migration of dissociated Li into the cathode and dissociated F into the anode. Electronic device simulations reveal that the former improves electron injection by lowering the Schottky barrier height, while the latter reduces the barrier width. These reduce turn-on voltage and improve current density and charge balance in LEDs. We fabricate PeLEDs with and without the LiF interlayer and link these materials and electronic phenomena to the device light-current-voltage characteristics. X-ray photoelectron spectroscopy obtained in sputter profiling of PeLEDs corroborates the dissociation of LiF.

Fading study and readout optimization for routinely use of LiF:Mg,Ti thermoluminescent detectors for personal dosimetry

LiF:Mg,Ti thermoluminescent dosimeters (TLDs) are frequently used for personal dosimetry by individual monitoring services (IMS) all over the world. This study focused on the investigation and accurate description of thermoluminescent signal fading in these dosimeters. The routine readout procedure was performed with the controlled heating of the detector elements according to defined time-temperature profiles (TTPs). The output of this procedure was a temperature dependent light signal, called glow curve. Additionally, the readout optimization was achieved with the simulation and validation of glow curves with different fast readout TTPs. The TLDs were annealed, irradiated and read out with different storing times at an ambient temperature of 25 °C. Six batches of each 100 TLDs were irradiated and read out with different TTPs and compared afterwards. A fading study with several Harshaw TLD-100 dosimeters was performed, in which the results were responses to describe the pre-irradiation fading and the post-irradiation fading with mathematical functions that give a correction factor for the dose calculation.

A new approach to the 2D radiation dosimetry based on optically stimulated luminescence of LiF:Mg,Cu,P

A new approach to the two-dimensional (2D) spatial radiation dosimetry based on optically stimulated luminescence (OSL) phenomena is presented. By investigating prototype dosimeters in form of flat and flexible sheets made of a polymer (PDMS), with the embedded OSL active grains (LiF:Mg,Cu,P), direct measurements of the 2D dose distribution using the OSL method and self-developed optical setup were verified. We have determined the response of 2D OSL prototype silicone foils, stimulated with the blue LEDs (470 nm) and read out using the CCD camera system, after doses of beta radiation ranging from less than 0.1 Gy up to 100 Gy. We have also verified the basic dosimetric parameters of the prototype sample foils, including the sensitivity (signal per dose), linearity, repeatability and fading effect. These encouraging results are the first step towards the practical use of LiF:Mg,Cu,P 2D OSL foils as a reusable spatial dosimeter system.

Low temperature thermoluminescence anomaly of LiF:Mg,Cu,P radiation detectors exposed to 1H and 4He ions

Lithium fluoride thermoluminescent radiation detectors with different dopant concentrations (7LiF:Mg,Ti and 7LiF:Mg,Cu,P) were exposed to 1H and 4He ions at the Heavy Ion Medical Accelerator in Chiba (HIMAC) in order to investigate their response to energetic light charged particles. Computer simulations with the Monte Carlo code PHITS were performed for a better interpretation of the experimental data. The results were compared with literature efficiency data and with the results of a recently developed microdosimetric efficiency model. In case of the main peak signal of 7LiF:Mg,Ti detectors, the determined efficiency values are in good agreement with previous investigations. Discrepancies in the efficiency of high temperature signal due to well-known non-linearity effects are reported. For 7LiF:Mg,Cu,P detectors, an anomalous thermoluminescence behavior in the low temperature part of the signal was found and discussed. Depending on the light quantification process, differences up to 30% in the dose assessment can be obtained, affecting also the relative efficiency determination process. An explanation of this phenomenon as a consequence of local migration of the charged carriers between the low temperature peaks and the main peak is presented. The implications of these findings on the use of LiF:Mg,Cu,P detectors in radiation environments characterized by the presence of 1H and 4He ions (i.e. space and proton therapy) are discussed. In order to avoid the occurrence of this anomalous behavior, it is advised to pre-heat the detectors after energetic light particle exposures.

LITHIUM FLUORIDE CRYSTALS AS FLUORESCENT NUCLEAR TRACK DETECTORS.

Radiophotoluminescence signal of LiF crystals was found to be sufficiently strong to visualize tracks of a single charged particle. This was achieved with a wide-field fluorescent microscope equipped with a ×100 objective and LiF single crystals grown with the Czochralski method at IFJ PAN. The tracks of alpha particles, protons, as well as products of 6Li(n,α)3H reaction with thermal neutrons (moderated Pu/Be source), were observed. These encouraging results are the first steps towards practical use of LiF as fluorescent nuclear track detectors. The most promising dosimetric application seems to be neutron measurements.

The use of TLDs for brachytherapy dosimetry

Thermoluminescent dosimeters (TLDs) are routinely used to measure the dose around brachytherapy sources due to their small size and high precision. This work presents a concise overview of the use of LiF:Mg,Ti TLDs for brachytherapy dosimetry including the experimental procedures required to achieve high-precision measurements as well as new results regarding the intrinsic energy dependence with some of the commonly used brachytherapy sources. Equations to correct TLD light output to air kerma are outlined and a description of the method to determine the intrinsic energy dependence is presented. For the intrinsic energy dependence investigation, a review of previously published results is presented as well as new experimental results using 125I, 103Pd, 192Ir, and miniature x-ray brachytherapy sources at the University of Wisconsin Medical Radiation Research Center (UWMRRC). The results of these experiments are consistent with previous work and give valuable insight to investigators using TLDs for brachytherapy measurements.

Determination of ochratoxin A in wines by capillary liquid chromatography with laser induced fluorescence detection using dispersive liquid–liquid microextraction

A method based on reverse phase capillary high performance liquid chromatography (capillary HPLC) coupled to laser-induced fluorescence detection (LIF) has been proposed for the determination of ochratoxin A (OTA) in wine samples. An anionic micellar medium was added to the mobile phase for increasing the fluorescence intensity and peak efficiency. Dispersive liquid–liquid microextraction (DLLME) has been used as a simple and efficient sample pretreatment method for the analysis of OTA in wines, being optimised by means of experimental design. The limit of detection was 5.5ngL−1 (3×S/N) and recoveries for different wines ranged from 91.7 to 98.1%. The proposed methodology could be classified as a green analytical chemistry alternative, combining the low organic solvent volumes required in the DLLME with the reduced consumption of mobile phase in capillary HPLC. The use of LIF as detector provided an extremely sensitive method for the determination of OTA in wines.

On the linearity of the high-temperature emission from 7LiF:Mg,Ti (TLD-700)

It is known since the early 1970s [e.g., Jähnert, B., 1972. The response of TLD-700 thermoluminescent dosemeters to protons and alpha particles. Health Phys. 23, 112–114.] that the high-temperature emission (HTE) from LiF:Mg,Ti thermoluminescence (TL) phosphors shows a distinctly different LET dependence than the dominant glow peak 5. This behaviour of the high-temperature structure can be attributed to the earlier onset of supralinearity compared to peak 5. The relative TL-efficiency of the high-temperature peaks after heavy ion irradiation with respect to 60Co was calculated by Waligórski and Katz [1980a. Supralinearity of peak 5 and 6 in TLD-700. Nucl. Instrum. Meth. 175, 48–50; 1980b. Supralinearity of peak 5 and 6 in TLD-700. Nucl. Instrum. Meth. 172, 463–470.], demonstrating that levels far exceeding 1 can be reached. The HTE from LiF:Mg,Ti has been applied in various ways, e.g., to determine an “effective” LET under mixed ion field conditions and, subsequently, to correct the absorbed dose deposited in the crystal for TL-efficiency [Berger, T., 2003. Dose assessment in mixed radiation fields—special emphasis on space dosimetry. Ph.D. Thesis, Vienna University of Technology; Berger, T., Hajek, M., Fugger, M., Vana, N., 2006a. Efficiency corrected dose verification with thermoluminescence dosemeters in heavy ion beams. Radiat. Prot. Dosim. 120, 361–364; Berger, T., Reitz, G., Hajek, M., Vana, N., 2006b. Comparison of various techniques for the exact determination of absorbed dose in heavy ion fields using passive detectors. Adv. Space Res. 37, 1716–1721.]. This approach showed good results in the low dose region (≤100 mGy). A crucial requirement for this procedure is the linearity of the gamma dose–response of the HTE for the applied dose levels. The discussion whether a linear dose–response can be found is still ongoing: while some groups reported a linear dose–response [Pradhan, A.S., Rassow, J., Meissner, P., 1985. Dosimetry of d(14)+ Be neutrons with the two-peak method of LiF TLD-700. Phys. Med. Biol. 30, 1349–1354; Massillon-Jl, G., Gamboa-deBuen, I., Brandan, M.E., 2006. Onset of supralinear response in TLD-100 exposed to 60Co gamma-rays. J. Phys. D: Appl. Phys. 39, 262–268.; Bilski, P., 2006. Response of various LiF thermoluminescent detectors to high energy ions—results of the ICCHIBAN experiment. Nucl. Instrum. Meth. Phys. Res. B 251, 121–126.] others measured a pronounced supralinearity even at very low doses [Horowitz, Y.S., Satinger, D., Puks, E., Oster, L., Podgalov, 2003. On the use of LiF:Mg, Ti TLDs in space—a critical review. Radiat. Prot. Dosim. 106, 7–25.; Horowitz, Y.S., Oster, L., Datz, H., 2007. The thermoluminescence dose–response and other characteristics of the high-temperature TL in LiF:Mg, Ti (TLD-100). Radiat. Prot. Dosim. 124, 191–205.]. This paper focuses on the results from a linearity study of the HTE in the dose region between 1 and 500 mGy.

Dose assessment at a phosphate industry landfill using solid state detectors

The industrial landfill “Racó de la Pubilla” is located at Flix (Tarragona, Spain) and contains residues from a factory that produces bicalcium phosphate using phosphorite. The main aim of the study was the determination of the environmental radiological conditions in the landfill in order to estimate the effective dose received by workers and the potential impact on the surrounding area. With these objectives in mind, a system based on LiF:Mg,Cu,P thermoluminescent detectors (TLD) and electrets was used. The main dosimetric characteristics of the TLD system are presented (LID, energy response, isotropy, etc.), as well as the results of the influence of environmental conditions on the electrets. The evaluation of the gamma ambient dose equivalent measured at the landfill by the TLD technique gives a maximum value of approximately 200 nSv/h, but most of the measurement points were close to the unaltered site (80 nSv/h). In addition, average radon concentrations of 30 Bq / m 3 were measured, slightly higher than the reference value. The effective dose due to the natural radioactive components of the waste is lower than 1 mSv/year. The use of LiF:Mg,Cu,P, with a sensitivity 30–40 times higher than LiF:Mg,Ti, and electrets for radon measurements allow short measurement periods, thus providing an easy assessment of the radiological risk of the studied facility.

The use of LiF (TLD‐100) as an out‐of‐field dosimeter

The commonly used thermoluminescent dosimeter TLD‐100 (Harshaw Chemical Company, Solon, OH) responds not only to photons and electrons, but also to neutrons that are produced during high‐energy therapies. As a result, TLD‐100 measurements outside of the treatment field are suspect when high‐energy radiation is used. Although alternatives such as TLD‐700 do not respond to neutrons, specialty dosimeters of this kind are expensive and are not routinely used in most clinics. In the current study, we examined the accuracy of TLD‐100 in measuring the out‐of‐field photon dose as a function of treatment energy.To determine the accuracy of TLD‐100 as compared with TLD‐700, TLD‐100 was irradiated outside of the treatment field by medical accelerators operated at 6, 10, 15, and 18 MV. In an effort to eliminate the response of TLD‐100 to neutrons, TLD capsules were encased in varying thicknesses of cadmium foil (0.25 – 0.75 mm) before being irradiated at 18 MV. The out‐of‐field TLD‐100 was found to be accurate at 6 MV and 10 MV, but to be substantially over‐responsive at 15 MV and 18 MV (by up to 1063% relative to TLD‐700). By wrapping the TLD‐100 in up to 0.75 mm of cadmium, it was possible to drastically reduce (down to 39% on average) the over‐response of the TLD‐100; however, total removal of the over‐responsiveness was not possible. Although TLD‐100 is well suited for measuring out‐of‐field dose at energies as high as 10 MV, at higher energies (15 MV or greater), this dosimeter over‐responds substantially and should not be used. Although encasing the TLD in cadmium minimized over‐response to a degree, the reduction was not sufficient to make TLD‐100 viable for measuring out‐of‐field dose at high treatment energies.PACS numbers: 87.52.‐g, 87.53.‐j, 87.53.‐Dq

Reduction process of uranium(IV) and uranium(III) in molten fluorides

This study focused on the electroreduction process of uranium cations in molten fluorides. It involved cyclic voltammetry, chronopotentiometry with and without current reversal, and square wave voltammetry. The results indicate a two-step reduction process for uranium(IV). The first step U(IV)/U(III) exchanging one electron corresponds to a soluble/soluble system and is limited by U(IV) diffusion with D U(IV) = 1.25 ± 0.35 × 10 −5 cm 2 s −1 in LiF–NaF at 720 °C. In order to perform a thorough study of the second step U(III)/U(0) in the reduction process, the melt was chemically reduced in U(III) with U metal as reducing agent. Alternatively to the use of LiF–NaF where U metal is unstable at 720 °C, the chemical reduction of U(IV) in U(III) was performed in a LiF–CaF 2–UF 4 solution containing U metal at 810 °C. It has been confirmed that the reduction of U(III) proceeds in one step exchanging three electrons and by a diffusion controlled process with D U(III) = 2.2 ± 0.7 × 10 −5 cm 2 s −1 in LiF–CaF 2 at 810 °C.

The application of LiF:Mg,Cu,P to large scale personnel dosimetry: current status and future directions

LiF:Mg,Cu,P is starting to replace LiF:Mg,Ti in a variety of personnel dosimetry applications. LiF:Mg,Cu,P has superior characteristics as compared to LiF:Mg,Ti including, higher sensitivity, improved energy response for photons, lack of supralinearity and insignificant fading. The use of LiF:Mg,Cu,P in large scale dosimetry programs is of particular interest due to the extreme sensitivity of this material to the maximum readout temperature, and the variety of different dosimetry aspects and details that must be considered for a successful implementation in routine dosimetry. Here we discuss and explain the various aspects of large scale LiF:Mg,Cu,P based dosimetry programs including the properties of the TL material, new generation of TLD readers, calibration methodologies, a new generation of dose calculation algorithms based on the use of artificial neural networks and the overall uncertainty of the dose measurement. The United States Navy (USN) will be the first US dosimetry processor who will use this new material for routine applications. Until June 2002, the Navy used two types of thermoluminescent materials for personnel dosimetry, CaF2:Mn and LiF:Mg,Ti. A program to upgrade the system and to implement LiF:Mg,Cu,P, started in the mid 1990s and was recently concluded. In 2002, the new system replaced the LiF:Mg,Ti and is scheduled to start replacing the CaF2:Mn system in 2006. A pilot study to determine the dosimetric performance of the new LiF:Mg,Cu,P based dosimetry system was recently completed, and the results show the new system to be as good or better than the current system in all areas tested. As a result, LiF:Mg,Cu,P is scheduled to become the primary personnel dosimeter for the entire US Navy in 2006.

Development of a measurement system for nitrate radical and dinitrogen pentoxide using a thermal conversion/laser-induced fluorescence technique

An instrument for measuring atmospheric nitrate radical (NO3) and dinitrogen pentoxide (N2O5) has been developed by a thermal conversion/laser-induced fluorescence (TC/LIF) technique. N2O5 is thermally decomposed and converted to NO3, which is measured by laser-induced fluorescence. In situ, fast-response, sensitive measurement of NO3∕N2O5 is expected by use of LIF. In detecting NO3, dual-wavelength excitation at 622.96 and 618.81nm was adopted to remove potential interference and to guarantee high selectivity. A high-power dye laser system was used as the source of excitation light. To measure ambient air directly, the NO3 detection cell was placed on the rooftop. The laser beam was guided by an optical fiber into the excitation cell. Transmittance of the laser beam was 80% for a 10m long fiber. To calibrate the instrument, the series of thermal decomposition of N2O5 and the gas phase titration of NO3 by NO were conducted. NO3 reduction by adding NO was also applied to determine accurately the zero points of the detector. After optimization of conditions such as gate timing in photon counting and the settings of the N2O5 converter, the present detection limits of NO3 and N2O5 were determined to be 4 and 6pptv, respectively, for the integration time of 10min (signal-to-noise ratio=1). It was confirmed that the interference of NO2 on N2O5 detection is negligible, but can be significant for NO3 measurement when NO2 concentration is extremely high (>100ppbv). Measurement of N2O5 in ambient air was made in the urban area of Tokyo, Japan. Observed data demonstrated the capacity of the TC/LIF instrument with a powerful dye laser and a single-path excitation cell for ambient measurements. In this article, we focus on the instrumentation and characterization.

Use of LiF to Achieve a Low-Temperature Co-Fired Ceramics (LTCC) with Low Dielectric Loss

Use of LiF to Achieve a Low-Temperature Co-Fired Ceramics (LTCC) with Low Dielectric Loss

Development of a measurement system of peroxy radicals using a chemical amplification/laser-induced fluorescence technique

An instrument for measuring atmospheric peroxy radicals has been developed by chemical amplification/laser-induced fluorescence (PERCA/LIF) technique. The small concentration of peroxy radicals is converted to the large amount of NO2, which is measured by laser-induced fluorescence instead of luminol chemiluminescence. Several advantages, that is, high sensitivity, high selectively, and fast time response, are expected by use of LIF for the NO2 measurement, in comparison with luminol chemiluminescence. When using this system, simultaneous measurements of NO2 and peroxy radicals are available. The present optimum condition for the reaction tube (1/4 in. Teflon) was determined to be the reaction tube length of 3 m, the NO and CO concentrations of 3 ppmv and 10%, respectively. The calibration, including humidity dependence of the detection sensitivity of peroxy radicals, was conducted and the present detection limit of peroxy radicals was determined to be 2.7 and 3.6 pptv at the ambient relative humidity of 50 and 80%, respectively, for the integration time of 1 min (S/N=2). This detection limit was calculated assuming the ambient O3 and NO2 mixing ratios of 30 and 20 ppbv, respectively. The influence of the NO2 detection sensitivity by adding high concentrations of CO was investigated and the quenching of excited NO2 by CO can affect the ambient measurement significantly under the high NO2 and low peroxy radical concentrations. Exploratory ambient air measurements were made in suburban area of Osaka, Japan. These results demonstrated the performance of PERCA/LIF for ambient measurements.