Overview of iodine generation for oxygen-iodine lasers

NASA Astrophysics Data System (ADS)

Jirásek, Vít.

2012-01-01

A review of the methods for generation of iodine for oxygen-iodine lasers (OIL) is presented. The chemical and physical methods for production of both atomic (AI) and molecular (MI) iodine have been searched in order to improve the efficiency and/or technology of OILs. These trials were motivated by the estimations that a substantial part of singlet oxygen (SO) could be saved with these methods and the onset of the laser active medium will be accelerated. Vapour of MI can be generated by the evaporation of solid or pressurized liquid I2, or synthesized in situ by the reaction of Cl2 with either HI or CuI2. The chemical methods of generation of AI are based on the substitution of I atom in a molecule of HI or ICl by another halogen atom produced usually chemically. The discharge methods include the dissociation of various iodine compounds (organic iodides, I2, HI) in the RF, MW, DC-pulsed or DC-vortex stabilized discharge. Combined methods use discharge dissociation of molecules (H2, F2) to gain atoms which subsequently react to replace AI from the iodine compound. The chemical methods were quite successful in producing AI (up to the 100% yield), but the enhancement of the laser performance was not reported. The discharge methods had been subsequently improving and are today able to produce up to 0.4 mmol/s of AI at the RF power of 500 W. A substantial enhancement of the discharge- OIL performance (up to 40%) was reported. In the case of Chemical-OIL, the enhancement was reported only under the conditions of a low I2/O2 ratio, where the "standard" I2 dissociation by SO is slow. The small-signal gain up to 0.3 %/cm was achieved on the supersonic COIL using the HI dissociated in the RF discharge. Due to the complicated kinetics of the RI-I-I2-SO system and a strong coupling with the gas flow and mixing, the theoretical description of the problem is difficult. It, however, seems that we can expect the major improvement of the OIL performance for those systems, where

Noncontact optical detection of explosive particles via photodissociation followed by laser-induced fluorescence.

PubMed

Wynn, C M; Palmacci, S; Kunz, R R; Aernecke, M

2011-09-12

High-sensitivity (ng/cm²) optical detection of the explosive 2,4,6-trinitrotoluene (TNT) is demonstrated using photodissociation followed by laser-induced fluorescence (PD-LIF). Detection occurs rapidly, within 6 laser pulses (~7 ns each) at a range of 15 cm. Dropcasting is used to create calibrated samples covering a wide range of TNT concentrations; and a correspondence between fractional area covered by TNT and PD-LIF signal strength is observed. Dropcast data are compared to that of an actual fingerprint. These results demonstrate that PD-LIF could be a viable means of rapidly and remotely scanning surfaces for trace explosive residues.

An alternative laser driven photodissociation mechanism of pyrrole via π*1σ/S0 conical intersection

NASA Astrophysics Data System (ADS)

Nandipati, K. R.; Lan, Z.; Singh, H.; Mahapatra, S.

2017-06-01

A first principles quantum dynamics study of N-H photodissociation of pyrrole on the S0-1π σ*(A12) coupled electronic states is carried out with the aid of an optimally designed UV-laser pulse. A new photodissociation path, as compared to the conventional barrier crossing on the π*1σ state, opens up upon electronic transitions under the influence of pump-dump laser pulses, which efficiently populate both the dissociation channels. The interplay of electronic transitions due both to vibronic coupling and the laser pulse is observed in the control mechanism and discussed in detail. The proposed control mechanism seems to be robust, and not discussed in the literature so far, and is expected to trigger future experiments on the π*1σ photochemistry of molecules of chemical and biological importance. The design of the optimal pulses and their application to enhance the overall dissociation probability is carried out within the framework of optimal control theory. The quantum dynamics of the system in the presence of pulse is treated by solving the time-dependent Schrödinger equation in the semi-classical dipole approximation.

Amplified spontaneous emission in solar-pumped iodine laser

NASA Technical Reports Server (NTRS)

Cho, Yong S.; Hwang, In H.; Han, Kwang S.; Lee, Ja H.

1992-01-01

The amplified spontaneous emission (ASE) from a long pulse, solar-simulating radiation pumped iodine laser amplifier is studied. The ASE threshold pump intensity is almost proportional to the inverse of the laser gain length when the gas pressure is constant in the laser tube.

Laser-induced fluorescence method for on-line molecular isotopologues of iodine-127, iodine-129, iodine-131 detected in gaseous media using a tunable diode laser

NASA Astrophysics Data System (ADS)

Kireev, S. V.; Shnyrev, S. L.; Sobolevsky, I. V.

2016-06-01

The letter reports on the development of a laser-induced fluorescence method for on-line selective measurement of 127I2, 129I2, 131I2, 129I127I, 127I131I, 129I131I isotopologue concentrations in gaseous media. The method is based on the excitation of molecular iodine isotopologues’ fluorescence by tunable diode laser (632-637 nm) radiation at three or four wavelengths corresponding to the 127I2, 131I2, 129I127I, 129I131I absorption line centers. Boundary relations for concentrations of simultaneously measured iodine isotopologues is about 10-5-10-6.

Direct solar-pumped iodine laser amplifier

NASA Technical Reports Server (NTRS)

Han, Kwang S.; Hwang, In Heon; Kim, Khong Hon; Stock, Larry V.

1988-01-01

A XeCl laser pumped iodine laser oscillator was developed which will be incorporated into the Master Oscillator Power Amplifier (MOPA) system. The developed XeCl laser produces output energy of about 60 mJ per pulse. The pulse duration was about 10 nsec. The kinetic model for the solar-pumped laser was refined and the algorithm for the calculation of a set of rate equations was improved to increase the accuracy and the efficiency of the calculation. The improved algorithm was applied to explain the existing experimental data taken from a flashlamp pumped iodine laser for three kinds of lasants, i-C3F7I, n-C4F9I, and t-C4F9I. Various solid laser materials were evaluated for solar-pumping. The materials studied were Nd:YAG, Nd:YLF, and Cr:Nd:GSGG crystals. The slope efficiency of 0.17 percent was measured for the Nd:YLF near the threshold pump intensity which was 211 solar constants (29W/sq cm). The threshold pump intensity of the Nd:YAG was measured to be 236 solar constants (32W/sq cm) and the near-threshold slope efficiency was 0.12 percent. True CW laser operation of Cr:Nd:GSGG was possible only at pump intensities less than or equal to 1,500 solar constants (203 W/sq cm). This fact was attributed to the high thermal focusing effect of the Cr:Nd:GSGG rod.

An alternative laser driven photodissociation mechanism of pyrrole via πσ*1∕S0 conical intersection.

PubMed

Nandipati, K R; Lan, Z; Singh, H; Mahapatra, S

2017-06-07

A first principles quantum dynamics study of N-H photodissociation of pyrrole on the S 0 - 1 πσ * (A21) coupled electronic states is carried out with the aid of an optimally designed UV-laser pulse. A new photodissociation path, as compared to the conventional barrier crossing on the πσ*1 state, opens up upon electronic transitions under the influence of pump-dump laser pulses, which efficiently populate both the dissociation channels. The interplay of electronic transitions due both to vibronic coupling and the laser pulse is observed in the control mechanism and discussed in detail. The proposed control mechanism seems to be robust, and not discussed in the literature so far, and is expected to trigger future experiments on the πσ*1 photochemistry of molecules of chemical and biological importance. The design of the optimal pulses and their application to enhance the overall dissociation probability is carried out within the framework of optimal control theory. The quantum dynamics of the system in the presence of pulse is treated by solving the time-dependent Schrödinger equation in the semi-classical dipole approximation.

An alternative laser driven photodissociation mechanism of pyrrole via πσ*1∕S0 conical intersection

PubMed Central

Nandipati, K. R.; Lan, Z.; Singh, H.; Mahapatra, S.

2017-01-01

A first principles quantum dynamics study of N–H photodissociation of pyrrole on the S0−1πσ*(A21) coupled electronic states is carried out with the aid of an optimally designed UV-laser pulse. A new photodissociation path, as compared to the conventional barrier crossing on the πσ*1 state, opens up upon electronic transitions under the influence of pump-dump laser pulses, which efficiently populate both the dissociation channels. The interplay of electronic transitions due both to vibronic coupling and the laser pulse is observed in the control mechanism and discussed in detail. The proposed control mechanism seems to be robust, and not discussed in the literature so far, and is expected to trigger future experiments on the πσ*1 photochemistry of molecules of chemical and biological importance. The design of the optimal pulses and their application to enhance the overall dissociation probability is carried out within the framework of optimal control theory. The quantum dynamics of the system in the presence of pulse is treated by solving the time-dependent Schrödinger equation in the semi-classical dipole approximation. PMID:28595406

Modeling of a solar-pumped iodine laser

NASA Technical Reports Server (NTRS)

Wilson, J. W.; Lee, J. H.

1980-01-01

The direct conversion in space of solar radiation into laser radiation for power transmission to earth, satellites, or deep space probes shows promise as a reasonably simple technology and may have cost advantage in deployment and greater reliability compared to other methods of space power generation and transmission. The main candidates for solar pumping are the gas dynamic, photochemical, and direct photoexcited lasers. Here consideration is given to the photochemical reaction of alkyliodides which predominantly excite the I(2P1/2) state which then lases at 1.315 microns. The iodine ground state is eventually lost to reconstituting the gas or in the formation of molecular iodine. The rates at which the gas is required to be recycled through the laser system are modest. The side exposure at 100-fold solar concentration of a 100-m long tube with a 1 sq m cross section is estimated to provide 20 kW of continuous laser output. Scaling laws and optimum operating conditions of this system are discussed.

Design and chemical synthesis of iodine-containing molecules for application to solar-pumped I* lasers

NASA Technical Reports Server (NTRS)

Shiner, C. S.

1986-01-01

The design and chemical synthesis of new media for solar pumped iodine molecule lasers are explored. In an effort to prepare an iodo fluorocarbon compound absorbing strongly at 300 nm or above, the synthesis of perfluoro allylic iodides was investigated. These compounds furnish especially stable allylic radicals upon photodissociation. The desired red shift is anticipated in the absorption maximum could correlate with increasing radical stability. This expectation was based upon the analysis, previously reported, of the structures and absorption maxima of compounds studied earlier. A previously unknown substance was prepared, a prototypical target molecule, perfluoro-3-iodocyclopent-1-ene. It was obtained by reaction of perfluorocyclopentene with sulfur trioxide under the influence of antimony pentafluoride catalyst, followed by treatment of the resulting allylic fluorosulfonate with sodium iodide in sulfoland solvent. Preliminary data indicate that the absorption maximum for the iodo fluorocarbon is not shifted significantly to longer wavelength. It is not certain whether this result reflects an unexpected influence of the cyclic structure upon the position of the absorption maximum.

CW molecular iodine laser pumped with a low power DPSSL

NASA Astrophysics Data System (ADS)

Luhs, W.; Wellegehausen, B.; Goyal, M.

2017-04-01

Cw oscillation of molecular iodine on many lines in the range of 557-802 nm pumped with a low power common diode pumped and frequency doubled solid state laser DPSSL is reported. The DPSSL is temperature stabilized, operates in single frequency and can be tuned by about 2 nm at 532 nm. Operation conditions of this simple and low cost iodine ring laser will be described and possible applications will be discussed.

Active medium gain study of electric-discharge oxygen-iodine laser

NASA Astrophysics Data System (ADS)

Kolobyanin, Yuriy; Adamenkov, Yuriy; Vyskubenko, Boris; Goryachev, Leonid; Ilyin, Sergey; Kalashnik, Anatoliy; Rakhimova, Tatiana; Rogozhnikov, Georgiy

2007-05-01

The paper reports on experimental studies of the active medium gain in supersonic electric-discharge oxygen-iodine laser (DOIL) based on traveling mw discharge. The measurements have included: absolute concentration, yield, and energy efficiency of production of SO in pure oxygen and oxygen-helium mixes at an oxygen partial pressure 3 to 15 Torr. For the gas flow to get rid of atomic oxygen, both heterogeneous mercury oxide coatings of the tube walls and homogeneous additives to the work mix, such as nitrogen oxide, have been used. The active medium of DOIL was formed using a nozzle array of the type of ejector sized as 10*50 mm2. The singlet oxygen-helium mix was supplied through three rows of sonic cylindrical nozzles, while the iodine-carrier gas mix - through two rows of supersonic conical nozzles with a half-opening angle of 10°(arc). The gas-phase iodine was produced in a quartz cell filled with iodine crystals. Room-temperature iodine vapors were picked up with a carrier gas (nitrogen or helium) and thus delivered into the nozzle array. The active medium was investigated by the high-resolution laser diode spectroscopy approach that used the laser type Vortex 6025 purchased from New Focus, Inc. The laser medium gain factor was determined by the intra-cavity approach having a sensitivity about 1*10 -6 cm -1. The static temperature of the medium was determined from the measurements of gain half-width. The gain of the active medium of electric-discharge OIL has been investigated. The DOIL in use was operating on a mix composed as O II:He=1:1 at a total pressure of 6 Torr and flowrate - about 1 mmol/s. With helium as an iodine carrier gas at a flowrate ~3 mmol/s, we have recorded a positive gain in the DOIL medium.

A solar simulator-pumped atomic iodine laser

NASA Technical Reports Server (NTRS)

Lee, J. H.; Weaver, W. R.

1981-01-01

An atomic iodine laser, a candidate for the direct solar-pumped gas laser, was excited with a 4-kW beam from a xenon arc solar simulator. Continuous lasing at 1.315 micron for over 10 ms was obtained for static filling of n-C3F7I vapor. By momentarily flowing the lasant, a 30-Hz pulsed output was obtained for about 200 ms. The peak laser power observed was 4 W for which the system efficiency reached 0.1%. These results indicate that direct solar pumping of a gas laser for power conversion in space is indeed feasible.

Initial state-specific photodissociation dynamics of pyrrole via 1 π σ ∗/ S 0 conical intersection initiated with optimally controlled UV-laser pulses

NASA Astrophysics Data System (ADS)

Nandipati, K. R.; Kanakati, Arun Kumar; Singh, H.; Lan, Z.; Mahapatra, S.

2017-09-01

Optimal initiation of quantum dynamics of N-H photodissociation of pyrrole on the S0-1πσ∗(1A2) coupled electronic states by UV-laser pulses in an effort to guide the subsequent dynamics to dissociation limits is studied theoretically. Specifically, the task of designing optimal laser pulses that act on initial vibrational states of the system for an effective UV-photodissociation is considered by employing optimal control theory. The associated control mechanism(s) for the initial state dependent photodissociation dynamics of pyrrole in the presence of control pulses is examined and discussed in detail. The initial conditions determine implicitly the variation in the dissociation probabilities for the two channels, upon interaction with the field. The optimal pulse corresponds to the objective fixed as maximization of overall reactive flux subject to constraints of reasonable fluence and quantum dynamics. The simple optimal pulses obtained by the use of genetic algorithm based optimization are worth an experimental implementation given the experimental relevance of πσ∗-photochemistry in recent times.

Design and chemical synthesis of iodine-containing molecules for application to solar-pumped I* lasers

NASA Technical Reports Server (NTRS)

Shiner, C. S.

1985-01-01

This work is directed toward the design and chemical synthesis of new media for solar-pumped I* lasers. In view of the desirability of preparing a perfluoroalkyl iodide absorbing strongly at 300 nm, the relationship betwen perfluoroalkyl iodide structure and the corresponding absorption wavelength was reexamined. Analysis of existing data suggests that, in this family of compounds, the absorption maximum shifts to longer wavelength, as desired, as the C-I bond in the lasant is progressively weakened. Weakening of the C-I bond correlates, in turn, with increasing stability of the perfluoroalkyl radical formed upon photodissociation of the iodide. The extremely promising absorption characteristics of perfluoro-tert-butyl iodide can be accounted for on this basis. A new technique of diode laser probing to obtain precise yields of I* atoms in photodissociation was also developed.

Optically (solar) pumped oxygen-iodine lasers

NASA Astrophysics Data System (ADS)

Danilov, O. B.; Zhevlakov, A. P.; Yur'ev, M. S.

2014-07-01

We present the results of theoretical and experimental studies demonstrating the possibility of developing an oxygen-iodine laser (OIL) with direct optical pumping of molecular oxygen involving inter-molecular interaction with charge transfer from donor molecule (buffer gas) to acceptor molecule (oxygen). This interaction lifts degeneracy of the lower energy states of molecular oxygen and increases its absorption cross section in the visible spectral region and the UV Herzberg band, where high quantum yield of singlet oxygen is achieved (QY ˜ 1 and QY ˜ 2, respectively) at the same time. A pulse-periodic optical pump sources with pulse energy of ˜50 kJ, pulse duration of ˜25 μs, and repetition rate of ˜10 Hz, which are synchronized with the mechanism of singlet oxygen generation, are developed. This allows implementation of a pulse-periodic oxygen-iodine laser with an efficiency of ˜25%, optical efficiency of ˜40%, and parameter L/ T ˜ 1/1.5, where T is the thermal energy released in the laser active medium upon generation of energy L. It is demonstrated that, under direct solar pumping of molecular oxygen, the efficiency parameter of the OIL can reach L/ T ˜ 1/0.8 in a wide range of scaling factors.

Investigation of laser-induced iodine fluorescence for the measurement of density in compressible flows

NASA Technical Reports Server (NTRS)

Mcdaniel, J. C., Jr.

1982-01-01

Laser induced fluorescence is an attractive nonintrusive approach for measuring molecular number density in compressible flows although this technique does not produce a signal that is directly related to the number density. Saturation and frequency detuned excitation are explored as means for minimizing the quenching effect using iodine as the molecular system because of its convenient absorption spectrum. Saturation experiments indicate that with available continuous wave laser sources of Gaussian transverse intensity distribution only partial saturation could be achieved in iodine at the pressures of interest in gas dynamics. Using a fluorescence lineshape theory, it is shown that for sufficiently large detuning of a narrow bandwidth laser from a molecular transition, the quenching can be cancelled by collisional broadening over a large range of pressures and temperatures. Experimental data obtained in a Mach 4.3 underexpanded jet of nitrogen seeded with iodine for various single mode argon laser detunings from a strong iodine transition at 5145 A are discussed.

Solar-pumped gas laser development

NASA Technical Reports Server (NTRS)

Wilson, J. W.

1981-01-01

The direct conversion of solar radiation into an inverted population for extraction in an optical cavity holds promise as a relatively simple system design. Broad-band photoabsorption in the visible or near-UV range is required to excite large volumes of gas and to ensure good solar absorption efficiency. The state excited must be a metastable state which is not quenched by the parent gas. The emission bandwidth must be less than approximately 10 A. The system should show chemical reversibility and an insensitivity to increasing temperature. Other properties such as good quantum efficiency and kinetic efficiency are also implied. A search of electronic-vibrational transitions in diatomic molecules satisfying these conditions is now in progress. A photodissociation-pumped atomic iodine laser is now being tested under solar pumping conditions. Photodissociation studies for thallium spin-flip metastable formation will begin in the near future.

Planar temperature measurement in compressible flows using laser-induced iodine fluorescence

NASA Technical Reports Server (NTRS)

Hartfield, Roy J., Jr.; Hollo, Steven D.; Mcdaniel, James C.

1991-01-01

A laser-induced iodine fluorescence technique that is suitable for the planar measurement of temperature in cold nonreacting compressible air flows is investigated analytically and demonstrated in a known flow field. The technique is based on the temperature dependence of the broadband fluorescence from iodine excited by the 514-nm line of an argon-ion laser. Temperatures ranging from 165 to 245 K were measured in the calibration flow field. This technique makes complete, spatially resolved surveys of temperature practical in highly three-dimensional, low-temperature compressible flows.

Improvement in Suppression of Pulsed Nd:YAG Laser Light With Iodine Absorption Cells for Filtered Rayleigh Scattering Measurements

NASA Technical Reports Server (NTRS)

Seasholtz, Richard G.; Buggele, Alvin E

1997-01-01

Filtered Rayleigh scattering using iodine absorption cells is an effective technique for obtaining density, temperature, and velocity measurements in high speed confined flows. By tuning a single frequency laser to a strong iodine absorption line, stray scattered laser light can be greatly suppressed. For example, the minimum transmission predicted by an iodine absorption model calculation is less than 10(exp -5) at the 18788.44/cm line using a 200 mm absorption cell containing iodine vapor at 0.46 T. Measurements obtained by other researches using a CW Nd:YAG laser agree with the model calculations. However, measurements made by us and by others using Q-switched, injection-seeded, frequency doubled Nd:YAG lasers only show minimum transmission of about 3 x 10(exp -3). This greatly reduces the applicability of the filtered Rayleigh scattering technique using these lasers in experiments having large amounts of stray scattered laser light. The purposes of the present study are to characterize the spectrum of the excess light transmitted by the iodine cell and to make changes to the laser to reduce the transmitted laser light. Transmission data as a function of laser frequency for the iodine absorption line at 18788.44/cm are presented. A planar mirror Fabry-Perot interferometer was used to characterize the frequency spectrum of the light passed through the cell. Measurements taken with the laser tuned to the center of the iodine absorption line show the light transmitted through the iodine cell to have a component with a bandwidth of about 40 GHz. This is probably caused by other modes in the laser that exist in spite of the single frequency injection beam. A second broadband component was also observed, possibly caused by the laser flash lamps or by fluorescence. An intracavity etalon was installed in the laser oscillator cavity to suppress the 40 GHz component. Measurements taken with the etalon tuned to the injection frequency showed a reduction in the transmitted

UV Photodissociation Action Spectroscopy of Haloanilinium Ions in a Linear Quadrupole Ion Trap Mass Spectrometer

NASA Astrophysics Data System (ADS)

Hansen, Christopher S.; Kirk, Benjamin B.; Blanksby, Stephen J.; O'Hair, Richard. A. J.; Trevitt, Adam J.

2013-06-01

UV-vis photodissociation action spectroscopy is becoming increasingly prevalent because of advances in, and commercial availability of, ion trapping technologies and tunable laser sources. This study outlines in detail an instrumental arrangement, combining a commercial ion-trap mass spectrometer and tunable nanosecond pulsed laser source, for performing fully automated photodissociation action spectroscopy on gas-phase ions. The components of the instrumentation are outlined, including the optical and electronic interfacing, in addition to the control software for automating the experiment and performing online analysis of the spectra. To demonstrate the utility of this ensemble, the photodissociation action spectra of 4-chloroanilinium, 4-bromoanilinium, and 4-iodoanilinium cations are presented and discussed. Multiple photoproducts are detected in each case and the photoproduct yields are followed as a function of laser wavelength. It is shown that the wavelength-dependent partitioning of the halide loss, H loss, and NH3 loss channels can be broadly rationalized in terms of the relative carbon-halide bond dissociation energies and processes of energy redistribution. The photodissociation action spectrum of (phenyl)Ag2 + is compared with a literature spectrum as a further benchmark.

Comparison Study of Subsonic and Transonic Mixing in a Multi-Kw Grid-Nozzle Supersonic Chemical Oxygen Iodine Laser

NASA Astrophysics Data System (ADS)

Vyskubenko, Oleg; Sugimoto, Daichi; Watanabe, Goro; Tei, Kazuyoku; Nanri, Kenzo; Fujioka, Tomoo

2005-05-01

The present study compares the laser medium properties for subsonic and transonic iodine injection schemes of a multi-kW grid-nozzle supersonic chemical oxygen iodine laser (COIL). Two supersonic nozzles of similar geometry having subsonic or transonic iodine injectors were investigated in the present study. Small signal gain (SSG) and internal cavity temperature (ICT) were experimentally measured as a function of the iodine flow rate and coordinate in the direction of the gas flow. Dissociated fraction of iodine F and the number N of O2(1Δ) molecules consumed for the dissociation of one iodine molecule were estimated by an analytical method, utilizing SSG and ICT as input parameters. Both gain and temperature were measured by diode laser spectroscopy. Pressure broadening of the spectroscopic line of iodine atom was taken into account when calculating the gas temperature in the cavity.

REVIEWS OF TOPICAL PROBLEMS: Gas lasers with solar excitation

NASA Astrophysics Data System (ADS)

Gordiets, B. F.; Panchenko, Vladislav Ya

1986-07-01

CONTENTS 1. Introduction 703 2. General requirements for laser media using solar excitation 704 3. Lasers with direct excitation by solar light 705 3.1. Basic characteristics of laser media. 3.2. Photodissociation Br2-CO2 lasers. 3.3. Interhalogen molecule lasers. 3.4. Iodine lasers. 3.5. Alkali metal vapor lasers. 4. Lasers with thermal conversion of solar pumping 709 4.1. General considerations. 4.2. CO2 laser with excitation in a black body cavity and with gas flow. 4.3. cw CO2 laser without gas flow. 5. Space laser media with solar excitation 713 5.1. Population inversion of molecular levels in the outer atmosphere of the Earth. 5.2. Laser effect in the atmospheres of Venus and Mars. 5.3. Terrestrial experimental technique for observing infrared emission in the atmospheres of planets. 5.4. Designs for laser systems in the atmospheres of Venus and Mars. 6. Conclusions 717 References 717

Relative quantum yield of I-asterisk(2P1/2) in the tunable laser UV photodissociation of i-C3F7I and n-C3F7I - Effect of temperature and exciplex emission

NASA Technical Reports Server (NTRS)

Smedley, J. E.; Leone, S. R.

1983-01-01

Wavelength-specific relative quantum yields of metastable I from pulsed laser photodissociation of i-C3F7I and n-C3F7I in the range 265-336 nm are determined by measuring the time-resolved infrared emission from the atomic I(P-2(1/2) P-2(3/2) transition. It is shown that although this yield appears to be unity from 265 to 298 nm, it decreases dramatically at longer wavelengths. Values are also reported for the enhancement of emission from metastable I due to exciplex formation at several temperatures. The exciplex formation emission increases linearly with parent gas pressure, but decreases with increasing temperature. Absorption spectra of i- and n-C3F7I between 303 and 497 K are presented, and the effect of temperature on the quantum yields at selected wavelengths greater than 300 nm, where increasing the temperature enhances the absorption considerably, are given. The results are discussed in regard to the development of solar-pumped iodine lasers.

Absolute frequency atlas from 915 nm to 985 nm based on laser absorption spectroscopy of iodine

NASA Astrophysics Data System (ADS)

Nölleke, Christian; Raab, Christoph; Neuhaus, Rudolf; Falke, Stephan

2018-04-01

This article reports on laser absorption spectroscopy of iodine gas between 915 nm and 985 nm. This wavelength range is scanned utilizing a narrow linewidth and mode-hop-free tunable diode-laser whose frequency is actively controlled using a calibrated wavelength meter. This allows us to provide an iodine atlas that contains almost 10,000 experimentally observed reference lines with an uncertainty of 50 MHz. For common lines, good agreement is found with a publication by Gerstenkorn and Luc (1978). The new rich dataset allows existing models of the iodine molecule to be refined and can serve as a reference for laser frequency calibration and stabilization.

A z-pinch photo-pumped pulsed atomic iodine laser

NASA Astrophysics Data System (ADS)

Stone, D. H.; Saunders, D. P.; Clark, M. C.

1984-03-01

A pulsed atomic iodine laser (CF3I) was designed and constructed using a coaxial xenon flash lamp as a pump source. The flash lamp was operated at low pressure to obtain pulse compression via xenon self-pinch. Electrical and optical diagnostics were performed for various xenon and CF3I pressures. Calorimeter data and burn patterns were obtained for the laser. Time-resolved spectroscopic data were taken throughout the CF3I pump band.

Theoretical study of the photodissociation of Li(2)+ in one-color intense laser fields.

PubMed

Li, Yuanjun; Jiang, Wanyi; Khait, Yuriy G; Hoffmann, Mark R

2011-05-07

A theoretical treatment of the photodissociation of the molecular ion Li(2) (+) in one-color intense laser fields, using the time-dependent wave packet approach in a Floquet Born-Oppenheimer representation, is presented. Six electronic states 1,2 (2)Σ(g)(+), 1,2 (2)Σ(u)(+), 1 (2)Π(g), and 1 (2)Π(u) are of relevance in this simulation and have been included. The dependences of the fragmental dissociation probabilities and kinetic energy release (KER) spectra on pulse width, peak intensity, polarization angle, wavelength, and initial vibrational level are analyzed to interpret the influence of control parameters of the external field. Three main dissociation channels, 1 (2)Σ(g)(+) (m = -1), 2 (2)Σ(g)(+) (m = -2), and 2 (2)Σ(u)(+) (m = -3), are seen to dominate the dissociation processes under a wide variety of laser conditions and give rise to well separated groups of KER features. Different dissociation mechanisms for the involved Floquet channels are discussed.

Branching ratios for TlBr photodissociation with 2660 A radiation

DOE Office of Scientific and Technical Information (OSTI.GOV)

White, J.C.; Zdasiuk, G.A.

1978-09-01

Radiation from a Nd:YAG laser was used to study the selective photodissociation of TlBr into the Tl metastable state, 6p/sup 2/P/sub 3/2/, as a potential candidate for stimulated Roman up-converters.(AIP)

Infrared Photodissociation Spectroscopy of Metal Ion -WATER Complexes

NASA Astrophysics Data System (ADS)

Bandyopadhyay, B.; Carnegie, P. D.; Duncan, M. A.

2011-06-01

Metal ion-water complexes are produced in a supersonic expansion cluster source via laser vaporization technique. Infrared photodissociation spectroscopy has been performed in the O-H stretch region. DFT calculations have also been carried out to obtain the structures and vibrational frequencies. Infrared spectra show partially resolved rotational structures which will be analyzed.

Numerical study of He/CF{sub 3}I pulsed discharge used to produce iodine atom in chemical oxygen-iodine laser

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang Jiao; Wang Yanhui; Wang Dezhen

2013-04-15

The pulsed discharge for producing iodine atoms from the alkyl and perfluoroalky iodides (CH{sub 3}I, CF{sub 3}I, etc.) is the most efficient method for achieving the pulse operating mode of a chemical oxygen-iodine laser. In this paper, a one-dimensional fluid model is developed to study the characteristics of pulsed discharge in CF{sub 3}I-He mixture. By solving continuity equation, momentum equation, Poisson equation, Boltzmann equation, and an electric circuit equation, the temporal evolution of discharge current density and various discharge products, especially the atomic iodine, are investigated. The dependence of iodine atom density on discharge parameters is also studied. The resultsmore » show that iodine atom density increases with the pulsed width and pulsed voltage amplitude. The mixture ratio of CF{sub 3}I and helium plays a more significant role in iodine atom production. For a constant voltage amplitude, there exists an optimal mixture ratio under which the maximum iodine atom concentration is achieved. The bigger the applied voltage amplitude is, the higher partial pressure of CF{sub 3}I is needed to obtain the maximum iodine atom concentration.« less

Iodine-stabilized single-frequency green InGaN diode laser.

PubMed

Chen, Yi-Hsi; Lin, Wei-Chen; Shy, Jow-Tsong; Chui, Hsiang-Chen

2018-01-01

A 520-nm InGaN diode laser can emit a milliwatt-level, single-frequency laser beam when the applied current slightly exceeds the lasing threshold. The laser frequency was less sensitive to diode temperature and could be finely tuned by adjusting the applied current. Laser frequency was stabilized onto a hyperfine component in an iodine transition through the saturated absorption spectroscopy. The uncertainty of frequency stabilization was approximately 8×10 -9 at a 10-s integration time. This compact laser system can replace the conventional green diode-pumped solid-state laser and applied as a frequency reference. A single longitudinal mode operational region with diode temperature, current, and output power was investigated.

Molecular Iodine Fluorescence Using a Green Helium-Neon Laser

ERIC Educational Resources Information Center

Williamson, J. Charles

2011-01-01

Excitation of molecular iodine vapor with a green (543.4 nm) helium-neon laser produces a fluorescence spectrum that is well suited for the upper-level undergraduate physical chemistry laboratory. Application of standard evaluation techniques to the spectrum yields ground electronic-state molecular parameters in good agreement with literature…

Temperature measurement in a compressible flow field using laser-induced iodine fluorescence

NASA Technical Reports Server (NTRS)

Fletcher, D. G.; Mcdaniel, J. C.

1987-01-01

The thermometric capability of a two-line fluorescence technique using iodine seed molecules in air is investigated analytically and verified experimentally in a known steady compressible flow field. Temperatures ranging from 165 to 295 K were measured in the flowfield using two iodine transitions accessed with a 30-GHz dye-laser scan near 543 nm. The effect of pressure broadening on temperature measurement is evaluated.

Injectant mole-fraction imaging in compressible mixing flows using planar laser-induced iodine fluorescence

NASA Technical Reports Server (NTRS)

Hartfield, Roy J., Jr.; Abbitt, John D., III; Mcdaniel, James C.

1989-01-01

A technique is described for imaging the injectant mole-fraction distribution in nonreacting compressible mixing flow fields. Planar fluorescence from iodine, seeded into air, is induced by a broadband argon-ion laser and collected using an intensified charge-injection-device array camera. The technique eliminates the thermodynamic dependence of the iodine fluorescence in the compressible flow field by taking the ratio of two images collected with identical thermodynamic flow conditions but different iodine seeding conditions.

Gain and temperature in a slit nozzle supersonic chemical oxygen-iodine laser with transonic and supersonic injection of iodine

NASA Astrophysics Data System (ADS)

Rosenwaks, Salman; Barmashenko, Boris D.; Bruins, Esther; Furman, Dov; Rybalkin, Victor; Katz, Arje

2002-05-01

Spatial distributions of the gain and temperament across the flow were studied for transonic and supersonic schemes of the iodine injection in a slit nozzle supersonic chemical oxygen-iodine laser as a function of the iodine and secondary nitrogen flow rate, jet penetration parameter and gas pumping rate. The mixing efficiency for supersonic injection of iodine is found to be much larger than for transonic injection, the maximum values of the gain being approximately 0.65 percent/cm for both injection schemes. Measurements of the gain distribution as a function of the iodine molar flow rate nI2 were carried out. For transonic injection the optimal value of nI2 at the flow centerline is smaller than that at the off axis location. The temperature is distributed homogeneously across the flow, increasing only in the narrow boundary layers near the walls. Opening a leak downstream of the cavity in order to decease the Mach number results in a decrease of the gain and increase of the temperature. The mixing efficiency in this case is much larger than for closed leak.

Oxygen-iodine ejector laser with a centrifugal bubbling singlet-oxygen generator

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zagidullin, M V; Nikolaev, V D; Svistun, M I

2005-10-31

It is shown that if a supersonic oxygen-iodine ejector laser is fed by singlet oxygen from a centrifugal bubbling generator operating at a centrifugal acceleration of {approx}400g, the laser output power achieves a value 1264 W at a chemical efficiency of 24.6% for an alkaline hydrogen peroxide flow rate of 208 cm{sup 3}s{sup -1} and a specific chlorine load of 1.34 mmol s{sup -1} per square centimetre of the bubble layer. (lasers)

Applications of the chemical oxygen-iodine laser

NASA Astrophysics Data System (ADS)

Latham, W. Pete; Kendrick, Kip R.; Quillen, Brian

2000-01-01

The Chemical Oxygen-Iodine Laser (COIL) has been developed at the Air Force Research Laboratory for military applications. For example, the COIL is to be use as the laser device for the ABL. A high power laser is useful for applications that require the delivery of a substantial amount of energy to a very small focused laser spot. The COIL is a member of the class of high power lasers that are also useful for industrial applications, including the materials processing task of high speed cutting and drilling. COIL technology has received considerable interest over the last several years due to its short, fiber- deliverable wavelength, scalability to very high powers, and demonstrated nearly diffraction-limited optical quality. These unique abilities make it an ideal candidate for nuclear reactor decommissioning and nuclear warhead dismantlement. Japanese researchers envision using a COIL for disaster cleanup and survivor rescue. It is also being studied by the oil and gas industry for well drilling. Any commercial or industrial application that requires very rapid, precise, and noninvasive cutting or drilling, could be readily accomplished with a COIL. Because of the substantial power levels available with a COIL, the laser could also be used for broad area applications such as paint stripping. This paper includes a collection of experiments accomplished at the Air Force Research Laboratory Chemical Laser Facility, including metal cutting, hole drilling, high power fiber optic transmission, and rock crushing.

Combined Infrared Multiphoton Dissociation with Ultraviolet Photodissociation for Ubiquitin Characterization

NASA Astrophysics Data System (ADS)

Halim, Mohammad A.; Girod, Marion; MacAleese, Luke; Lemoine, Jérôme; Antoine, Rodolphe; Dugourd, Philippe

2016-09-01

Herein we report the successful implementation of the consecutive and simultaneous photodissociation with high (213 nm) and low (10.6 μm) energy photons (HiLoPD, high-low photodissociation) on ubiquitin in a quadrupole-Orbitrap mass spectrometer. Absorption of high-energy UV photon is dispersed over the whole protein and stimulates extensive C-Cα backbone fragmentation, whereas low-energy IR photon gradually increases the internal energy and thus preferentially dissociates the most labile amide (C-N) bonds. We noticed that simultaneous irradiation of UV and IR lasers on intact ubiquitin in a single MS/MS experiment provides a rich and well-balanced fragmentation array of a/x, b/y, and z ions. Moreover, secondary fragmentation from a/x and z ions leads to the formation of satellite side-chain ions (d, v, and w) and can help to distinguish isomeric residues in a protein. Implementation of high-low photodissociation in a high-resolution mass spectrometer may offer considerable benefits to promote a comprehensive portrait of protein characterization.

Iodine-Catalyzed Isomerization of Dimethyl Muconate

DOE Office of Scientific and Technical Information (OSTI.GOV)

Settle, Amy E.; Berstis, Laura; Zhang, Shuting

cis,cis-Muconic acid is a platform biobased chemical that can be upgraded to drop-in commodity and novel monomers. Among the possible drop-in products, dimethyl terephthalate can be synthesized via esterification, isomerization, Diels-Alder cycloaddition, and dehydrogenation. The isomerization of cis,cis-dimethyl muconate ( ccDMM) to the trans,trans-form ( ttDMM) can be catalyzed by iodine; however, studies have yet to address (i) the mechanism and reaction barriers unique to DMM, and (ii) the influence of solvent, potential for catalyst recycle, and recovery of high-purity ttDMM. To address this gap, we apply a joint computational and experimental approach to investigate iodine-catalyzed isomerization of DMM. Densitymore » functional theory calculations identified unique regiochemical considerations due to the large number of halogen-diene coordination schemes. Both transition state theory and experiments estimate significant barrier reductions with photodissociated iodine. Solvent selection was critical for rapid kinetics, likely due to solvent complexation with iodine. Under select conditions, ttDMM yields of 95% were achieved in <1 h with methanol, followed by high purity recovery (>98%) with crystallization. Lastly, post-reaction iodine can be recovered and recycled with minimal loss of activity. Altogether, these findings provide new insight into the mechanism and conditions necessary for DMM isomerization with iodine to advance the state-of-the-art for biobased chemicals.« less

Iodine-Catalyzed Isomerization of Dimethyl Muconate

DOE PAGES

Settle, Amy E.; Berstis, Laura; Zhang, Shuting; ...

2018-04-16

cis,cis-Muconic acid is a platform biobased chemical that can be upgraded to drop-in commodity and novel monomers. Among the possible drop-in products, dimethyl terephthalate can be synthesized via esterification, isomerization, Diels-Alder cycloaddition, and dehydrogenation. The isomerization of cis,cis-dimethyl muconate ( ccDMM) to the trans,trans-form ( ttDMM) can be catalyzed by iodine; however, studies have yet to address (i) the mechanism and reaction barriers unique to DMM, and (ii) the influence of solvent, potential for catalyst recycle, and recovery of high-purity ttDMM. To address this gap, we apply a joint computational and experimental approach to investigate iodine-catalyzed isomerization of DMM. Densitymore » functional theory calculations identified unique regiochemical considerations due to the large number of halogen-diene coordination schemes. Both transition state theory and experiments estimate significant barrier reductions with photodissociated iodine. Solvent selection was critical for rapid kinetics, likely due to solvent complexation with iodine. Under select conditions, ttDMM yields of 95% were achieved in <1 h with methanol, followed by high purity recovery (>98%) with crystallization. Lastly, post-reaction iodine can be recovered and recycled with minimal loss of activity. Altogether, these findings provide new insight into the mechanism and conditions necessary for DMM isomerization with iodine to advance the state-of-the-art for biobased chemicals.« less

Singlet oxygen generator for a solar powered chemically pumped iodine laser

NASA Technical Reports Server (NTRS)

Busch, G. E.

1984-01-01

The potential of solid phase endoperoxides as a means to produce single-delta oxygen in the gas phase in concentrations useful to chemical oxygen-iodine lasers was investigated. The 1,4 - endoperoxide of ethyl 3- (4-methyl - 1-naphthyl) propanoate was deposited over an indium-oxide layer on a glass plate. Single-delta oxygen was released from the endoperoxide upon heating the organic film by means of an electrical discharge through the conductive indium oxide coating. The evolution of singlet-delta oxygen was determined by measuring the dimol emission signal at 634 nm. Comparison of the measured signal with an analytic model leads to two main conclusions: virtually all the oxygen being evolved is in the singlet-delta state and in the gas phase, and there is no significant quenching other than energy pooling on the time scale of the experiment (approximately 10 msec). The use of solid phase endoperoxide as a singlet-delta oxygen generator for an oxygen-iodine laser appears promising.

Calculation of the mixing chamber of an ejector chemical oxygen - iodine laser

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zagidullin, M V; Nikolaev, V D

2001-06-30

Gas parameters are calculated at the outlet of the mixing chamber of an ejector chemical oxygen-iodine laser with a nozzle unit consisting of nozzles of three types, which provides a total pressure of the active medium that substantially exceeds a pressure in the generator of singlet oxygen. This technique of forming the laser active medium substantially facilitates the ejection of the exhaust gas to the atmosphere by using a diffuser and single-stage vacuum systems based on water circulating pumps. (lasers, active media)

Singlet delta oxygen generation for Chemical Oxygen-Iodine Lasers

NASA Astrophysics Data System (ADS)

Georges, E.; Mouthon, A.; Barraud, R.

1991-10-01

The development of Chemical Oxygen-Iodine Lasers is based on the generation of singlet delta oxygen. To improve the overall efficiency of these lasers, it is necessary to increase the generator production and yield of singlet delta oxygen at low and high pressure, respectively, for subsonic and supersonic lasers. Furthermore, the water vapor content must be as low as possible. A generator model, based on gas-liquid reaction and liquid-vapor equilibrium theories associated with thermophysical evaluations is presented. From model predictions, operating conditions have been drawn to attain the following experimental results in a bubble-column: by increasing the superficial gas velocity, the production of singlet delta oxygen is largely improved at low pressure; by mixing chlorine with an inert gas before injection in the reactor, this yield is maintained constant up to higher pressure. A theoretical analysis of these experimental results and their consequences for both subsonic and supersonic lasers are presented.

Singlet Delta oxygen generation for chemical oxygen-iodine lasers

NASA Astrophysics Data System (ADS)

Georges, E.; Mouthon, A.; Barraud, R.

To improve the overall efficiency of chemical oxygen-iodine lasers, it is necessary to increase the generator production and yield of singlet delta oxygen at low and high pressure, respectively, for subsonic and supersonic lasers. The water vapor content must also be as low as possible. A generator model based on gas-liquid reaction and liquid-vapor equilibrium theories is presented. From model predictions, operating conditions have been drawn to attain the following experimental results in a bubble-column: by increasing the superficial gas velocity, the production of singlet delta oxygen is largely improved at low pressure; by mixing chlorine with an inert gas before injection in the reactor, this yield is maintained constant up to higher pressure.

Iodine-Catalyzed Isomerization of Dimethyl Muconate.

PubMed

Settle, Amy E; Berstis, Laura; Zhang, Shuting; Rorrer, Nicholas A; Hu, Haiming; Richards, Ryan M; Beckham, Gregg T; Crowley, Michael F; Vardon, Derek R

2018-06-11

cis,cis-Muconic acid is a platform bio-based chemical that can be upgraded to drop-in commodity and novel monomers. Among the possible drop-in products, dimethyl terephthalate can be synthesized via esterification, isomerization, Diels-Alder cycloaddition, and dehydrogenation. The isomerization of cis,cis-dimethyl muconate (ccDMM) to the trans,trans-form (ttDMM) can be catalyzed by iodine; however, studies have yet to address (i) the mechanism and reaction barriers unique to DMM, and (ii) the influence of solvent, potential for catalyst recycle, and recovery of high-purity ttDMM. To address this gap, we apply a joint computational and experimental approach to investigate iodine-catalyzed isomerization of DMM. Density functional theory calculations identified unique regiochemical considerations owing to the large number of halogen-diene coordination schemes. Both transition state theory and experiments estimate significant barrier reductions with photodissociated iodine. Solvent selection was critical for rapid kinetics, likely because of solvent complexation with iodine. Under select conditions, ttDMM yields of 95 % were achieved in <1 h with methanol, followed by high purity recovery (>98 %) with crystallization. Lastly, post-reaction iodine can be recovered and recycled with minimal loss of activity. Overall, these findings provide new insight into the mechanism and conditions necessary for DMM isomerization with iodine to advance the state-of-the-art for bio-based chemicals. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Singlet oxygen generator for a supersonic chemical oxygen iodine laser: parametric study and recovery of chemicals

NASA Astrophysics Data System (ADS)

Spalek, Otomar; Kodymova, Jarmila

1997-04-01

A jet singlet oxygen generator for a supersonic chemical oxygen-iodine laser was studied including singlet delta oxygen, O2(1(Delta) g), and residual chlorine concentration measurements. The investigation was intended mainly for a water vapor measurement in gas effluent of generator in dependence on properties of liquid jets: a chemical composition and temperature of the input liquid (alkaline solution of hydrogen peroxide), a liquid jets diameter and their geometrical arrangement. Effects of these parameters on output power of a small-scale supersonic laser were studied as well. Possible approaches to a chemical fuels management in a chemical oxygen-iodine laser for industrial applications are considered. An 'open loop' cycle with a possible use of sodium hydroxide, and a 'closed loop' cycle with a regeneration of both potassium hydroxide and hydrogen peroxide are discussed.

Optical Frequency Metrology of an Iodine-Stabilized He-Ne Laser Using the Frequency Comb of a Quantum-Interference-Stabilized Mode-Locked Laser

PubMed Central

Smith, Ryan P.; Roos, Peter A.; Wahlstrand, Jared K.; Pipis, Jessica A.; Rivas, Maria Belmonte; Cundiff, Steven T.

2007-01-01

We perform optical frequency metrology of an iodine-stabilized He-Ne laser using a mode-locked Ti:sapphire laser frequency comb that is stabilized using quantum interference of photocurrents in a semiconductor. Using this technique, we demonstrate carrier-envelope offset frequency fluctuations of less than 5 mHz using a 1 s gate time. With the resulting stable frequency comb, we measure the optical frequency of the iodine transition [127I2 R(127) 11-5 i component] to be 473 612 214 712.96 ± 0.66 kHz, well within the uncertainty of the CIPM recommended value. The stability of the quantum interference technique is high enough such that it does not limit the measurements. PMID:27110472

History of chemical oxygen-iodine laser (COIL) development in the USA

NASA Astrophysics Data System (ADS)

Truesdell, Keith A.; Helms, Charles A.; Hager, Gordon D.

1994-09-01

This is an overview of the development of Chemical Oxygen-Iodine Laser (COIL) technology in the United States. Key technical developments will be reviewed, beginning in 1960 and culminating in 1977 with the first COIL lasing demonstration at the Air Force Weapons Laboratory (now the Phillips Laboratory). The discussion will then turn to subsonic laser development, supersonic lasing demonstration and efficiency improvements, and finishing with a brief discussion of some spin off COIL technologies. Particular emphasis will be placed on how the O2 (1(Delta) ) generator and O2-I2 mixing nozzle technologies evolved.

History of chemical oxygen-iodine laser (COIL) development in the USA

NASA Astrophysics Data System (ADS)

Truesdell, Keith A.; Helms, Charles A.; Hager, Gordon D.

1995-03-01

This is an overview of the development of Chemical Oxygen-Iodine Laser (COIL) technology in the United States. Key technical developments will be reviewed, beginning in 1960 and culminating in 1977 with the first COIL lasing demonstration at the Air Force Weapons Laboratory (now the Phillips Laboratory). The discussion will then turn to subsonic laser development, supersonic lasing demonstration and efficiency improvements, and finishing with a brief discussion of some spin off COIL technologies. Particular emphasis will be placed on how the O2 (1(Delta) ) generator and O2-I2 mixing nozzle technologies evolved.

New singlet oxygen generator for chemical oxygen-iodine lasers

NASA Astrophysics Data System (ADS)

Yoshida, S.; Saito, H.; Fujioka, T.; Yamakoshi, H.; Uchiyama, T.

1986-11-01

Experiments have been carried out to investigate a new method for generating O2(1Delta) with long-time operation of an efficient chemical oxygen-iodine laser system in mind. An impinging-jet nozzle was utilized to atomize a H2O2-KOH solution so that the alkaline H2O2/Cl2 reaction might occur in droplet-gas phase with high excitation efficiency. Experimental results indicate that the present generator can yield as high as 80 percent of O2(1Delta) with reasonable O2 flow rate.

Iodine absorption cells quality evaluation methods

NASA Astrophysics Data System (ADS)

Hrabina, Jan; Zucco, Massimo; Holá, Miroslava; Šarbort, Martin; Acef, Ouali; Du-Burck, Frédéric; Lazar, Josef; Číp, Ondřej

2016-12-01

The absorption cells represent an unique tool for the laser frequency stabilization. They serve as irreplaceable optical frequency references in realization of high-stable laser standards and laser sources for different brands of optical measurements, including the most precise frequency and dimensional measurement systems. One of the most often used absorption media covering visible and near IR spectral range is molecular iodine. It offers rich atlas of very strong and narrow spectral transitions which allow realization of laser systems with ultimate frequency stabilities in or below 10-14 order level. One of the most often disccussed disadvantage of the iodine cells is iodine's corrosivity and sensitivity to presence of foreign substances. The impurities react with absorption media and cause spectral shifts of absorption spectra, spectral broadening of the transitions and decrease achievable signal-to-noise ratio of the detected spectra. All of these unwanted effects directly influence frequency stability of the realized laser standard and due to this fact, the quality of iodine cells must be precisely controlled. We present a comparison of traditionally used method of laser induced fluorescence (LIF) with novel technique based on hyperfine transitions linewidths measurement. The results summarize advantages and drawbacks of these techniques and give a recommendation for their practical usage.

Photodissociation of Small Molecules and Photoionization of Free Radicals Using the VUV Velocity-Map Imaging Photoion and Photoelectron Method

NASA Astrophysics Data System (ADS)

Gao, Hong

The tunable vacuum ultraviolet (VUV) laser generated through the two-photon resonance-enhanced four-wave mixing scheme is combined with the newly developed time-slice velocity map imaging photoion method to study the photodissociation of small molecules in the VUV region, and with the velocity map imaging photoelectron method to study the photoionization of free radicals. The photodissociation dynamics of NO in the energy region around 13.5 eV has been investigated. Branching ratios of the three lowest dissociation channels of 12C 16O that produce C(3P) + O(3P), C( 1D) + O(3P) and C(3P) + O(1D) are measured for the first time in the VUV region from 102,500 cm-1 to 110,500 cm-1, valuable information of the dissociation dynamics for this prototype system has been deduced. We demonstrated an experiment that has two independently tunable VUV lasers and a time-slice velocity map imaging setup, this provides us a global way to perform systematic state-selected photodissociation of small molecules via state-selected detection of the atomic products in the VUV region. The velocity map imaging photoelectron method was successfully used to obtain the photoelectron spectrum of the propargyl radical (C3H3) via a single VUV photoionization process. The propargyl radical is generated by the 193 nm laser photodissociation of the precursor C3H3Cl. This is the first time that the velocity map imaging photoelectron method is used to get the photoelectron spectra of free radicals, indicating that it is a powerful technique for studying the photoionization of free radicals which are always hard to be produced with high enough number densities for spectroscopic studies. This dissertation is mainly based on the following peer-reviewed journal articles: 1. Hong Gao, Yang Pan, Lei Yang, Jingang Zhou, C. Y. Ng and William M. Jackson. "Time-slice velocity-map ion imaging studies of the Photodissociation of NO in the vacuum ultraviolet region", the Journal of Chemical Physics, 136, 134302

Quantum yield for carbon monoxide production in the 248 nm photodissociation of carbonyl sulfide (OCS)

NASA Technical Reports Server (NTRS)

Zhao, Z.; Stickel, R. E.; Wine, P. H.

1995-01-01

Tunable diode laser absorption spectroscopy has been coupled with excimer laser flash photolysis to measure the quantum yield for CO production from 248 nm photodissociation of carbonyl sulfide (OCS) relative to the well-known quantum yield for CO production from 248 nm photolysis of phosgene (Cl2CO2). The temporal resolution of the experiments was sufficient to distinguish CO formed directly by photodissociation from that formed by subsequent S((sup 3)P(sub J)) reaction with OCS. Under the experimental conditions employed, CO formation via the fast S((sup 1)D(sub 2)) + OCS reaction was minimal. Measurements at 297K and total pressures from 4 to 100 Torr N2 + N2O show the CO yield to be greater than 0.95 and most likely unity. This result suggests that the contribution of OCS as a precursor to the lower stratospheric sulfate aerosol layer is somewhat larger than previously thought.

A unified planar measurement technique for compressible flows using laser-induced iodine fluorescence

NASA Technical Reports Server (NTRS)

Hartfield, Roy J., Jr.; Hollo, Steven D.; Mcdaniel, James C.

1992-01-01

A unified laser-induced fluorescence technique for conducting planar measurements of temperature, pressure and velocity in nonreacting, highly compressible flows has been developed, validated and demonstrated. Planar fluorescence from iodine, seeded into air, was induced by an argon-ion laser and collected using a liquid-nitrogen cooled CCD camera. In the measurement technique, temperature is determined from the fluorescence induced with the laser operated broad band. Pressure and velocity are determined from the shape and position of the fluorescence excitation spectrum which is measured with the laser operated narrow band. The measurement approach described herein provides a means of obtaining accurate, spatially-complete maps of the primary flow field parameters in a wide variety of cold supersonic and transonic flows.

Linkage and Anomeric Differentiation in Trisaccharides by Sequential Fragmentation and Variable-Wavelength Infrared Photodissociation

NASA Astrophysics Data System (ADS)

Tan, Yanglan; Polfer, Nicolas C.

2015-02-01

Carbohydrates and their derivatives play important roles in biological systems, but their isomeric heterogeneity also presents a considerable challenge for analytical techniques. Here, a stepwise approach using infrared multiple-photon dissociation (IRMPD) via a tunable CO2 laser (9.2-10.7 μm) was employed to characterize isomeric variants of glucose-based trisaccharides. After the deprotonated trisaccharides were trapped and fragmented to disaccharide C2 fragments in a Fourier transform ion cyclotron resonance (FTICR) cell, a further variable-wavelength infrared irradiation of the C2 ion produced wavelength-dependent dissociation patterns that are represented as heat maps. The photodissociation patterns of these C2 fragments are shown to be strikingly similar to the photodissociation patterns of disaccharides with identical glycosidic bonds. Conversely, the photodissociation patterns of different glycosidic linkages exhibit considerable differences. On the basis of these results, the linkage position and anomericity of glycosidic bonds of disaccharide units in trisaccharides can be systematically differentiated and identified, providing a promising approach to characterize the structures of isomeric oligosaccharides.

Chemical oxygen-iodine laser (COIL) for the dismantlement of nuclear facilities

NASA Astrophysics Data System (ADS)

Hallada, Marc R.; Seiffert, Stephan L.; Walter, Robert F.; Vetrovec, John

2000-05-01

The dismantlement of obsolete nuclear facilities is a major challenge for both the US Department of Energy and nuclear power utilities. Recent demonstrations have shown that lasers can be highly effective for size reduction cutting, especially for the efficient storage and recycling of materials. However, the full benefits of lasers can only be realized with high average power beams that can be conveniently delivered, via fiber optics, to remote and/or confined areas. Industrial lasers that can meet these requirements are not available now or for the foreseeable future. However, a military weapon laser, a Chemical Oxygen Iodine Laser (COIL), which has been demonstrated at over a hundred kilo Watts, could be adapted to meet these needs and enable entirely new industrial applications. An 'industrialized' COIL would enable rapid sectioning of thick and complex structures, such as glove boxes, reactor vessels, and steam generators, accelerating dismantlement schedules and reducing worker hazards. The full advantages of lasers in dismantlement could finally be realized with a portable COIL which is integrated with sophisticated robotics. It could be built and deployed in less than two years, breaking the paradigm of labor-intensive dismantlement operations and cutting processing times and costs dramatically.

Reduced dimer production in solar-simulator-pumped continuous wave iodine lasers based on model simulations and scaling and pumping studies

NASA Technical Reports Server (NTRS)

Costen, Robert C.; Heinbockel, John H.; Miner, Gilda A.; Meador, Willard E., Jr.; Tabibi, Bagher M.; Lee, Ja H.; Williams, Michael D.

1995-01-01

A numerical rate equation model for a continuous wave iodine laser with longitudinally flowing gaseous lasant is validated by approximating two experiments that compare the perfluoroalkyl iodine lasants n-C3F7I and t-C4F9I. The salient feature of the simulations is that the production rate of the dimer (C4F9)2 is reduced by one order of magnitude relative to the dimer (C3F7)2. The model is then used to investigate the kinetic effects of this reduced dimer production, especially how it improves output power. Related parametric and scaling studies are also presented. When dimer production is reduced, more monomer radicals (t-C4F9) are available to combine with iodine ions, thus enhancing depletion of the laser lower level and reducing buildup of the principal quencher, molecular iodine. Fewer iodine molecules result in fewer downward transitions from quenching and more transitions from stimulated emission of lasing photons. Enhanced depletion of the lower level reduces the absorption of lasing photons. The combined result is more lasing photons and proportionally increased output power.

Solar pumped laser

NASA Technical Reports Server (NTRS)

Lee, J. H.; Hohl, F.; Weaver, W. R. (Inventor)

1984-01-01

A solar pumped laser is described in which the lasant is a gas that will photodissociate and lase when subjected to sunrays. Sunrays are collected and directed onto the gas lasant to cause it to lase. Applications to laser propulsion and laser power transmission are discussed.

Comparing the efficiency of supersonic oxygen-iodine laser with different mixing designs

NASA Astrophysics Data System (ADS)

Vyskubenko, Boris A.; Adamenkov, A. A.; Bakshin, V. V.; Efremov, V. I.; Ilyin, S. P.; Kolobyanin, Yu. V.; Krukovsky, I. M.; Kudryashov, E. A.; Moiseyev, V. B.

2003-11-01

The paper presents experimental studies of supersonic oxygen-iodine laser (OIL) using twisted-flow singlet oxygen generator (SOG) over a wide range of the singlet oxygen pressures and the buffer gas flow rates. The experiments used different designs of the nozzle unit and mixing system for singlet oxygen and iodine gas with the carrier gas (such as nitrogen or helium). For a wide range of the key parameters, the study looked at the efficiency of supersonic OIL with variation of the singlet oxygen pressure. The measurements were made for different positions of the iodine injection plane with respect to the critical cross-section (both in the subsonic part of the nozzle and in the supersonic flow). The gas pressure at the nozzle unit entry was varied from 50 to 250 Torr. The total pressure loss have been found for different mixing designs. Experimental curves are given for energy performance and chemical efficiency of the supersonic OIL as a function of the key parameters. Comparison is made between the calculated and experimental data. For the optimum conditions of OIL operation, chemical efficiency of 25-30% has been achieved.

Laser power transmission

NASA Technical Reports Server (NTRS)

Conway, Edmund J.

1992-01-01

An overview of previous studies related to laser power transmission is presented. Particular attention is given to the use of solar pumped lasers for space power applications. Three general laser mechanisms are addressed: photodissociation lasing driven by sunlight, photoexcitation lasing driven directly by sunlight, and photoexcitation lasing driven by thermal radiation.

REVIEW: Excited states in the active media of oxygen — iodine lasers

NASA Astrophysics Data System (ADS)

Azyazov, V. N.

2009-11-01

A review of investigations of kinetic processes in active media oxygen — iodine lasers (OILs) performed in the last decade is presented. The mechanisms of pumping and quenching of electronically and vibrationally excited O2 and I2 molecules are considered, and dissociation mechanisms of I2 in the active medium of the OIL are analysed. The values of kinetic constants of processes proceeding in the active media of OILs are recommended.

Iodine Absorption Cells Purity Testing.

PubMed

Hrabina, Jan; Zucco, Massimo; Philippe, Charles; Pham, Tuan Minh; Holá, Miroslava; Acef, Ouali; Lazar, Josef; Číp, Ondřej

2017-01-06

This article deals with the evaluation of the chemical purity of iodine-filled absorption cells and the optical frequency references used for the frequency locking of laser standards. We summarize the recent trends and progress in absorption cell technology and we focus on methods for iodine cell purity testing. We compare two independent experimental systems based on the laser-induced fluorescence method, showing an improvement of measurement uncertainty by introducing a compensation system reducing unwanted influences. We show the advantages of this technique, which is relatively simple and does not require extensive hardware equipment. As an alternative to the traditionally used methods we propose an approach of hyperfine transitions' spectral linewidth measurement. The key characteristic of this method is demonstrated on a set of testing iodine cells. The relationship between laser-induced fluorescence and transition linewidth methods will be presented as well as a summary of the advantages and disadvantages of the proposed technique (in comparison with traditional measurement approaches).

Iodine Absorption Cells Purity Testing

PubMed Central

Hrabina, Jan; Zucco, Massimo; Philippe, Charles; Pham, Tuan Minh; Holá, Miroslava; Acef, Ouali; Lazar, Josef; Číp, Ondřej

2017-01-01

This article deals with the evaluation of the chemical purity of iodine-filled absorption cells and the optical frequency references used for the frequency locking of laser standards. We summarize the recent trends and progress in absorption cell technology and we focus on methods for iodine cell purity testing. We compare two independent experimental systems based on the laser-induced fluorescence method, showing an improvement of measurement uncertainty by introducing a compensation system reducing unwanted influences. We show the advantages of this technique, which is relatively simple and does not require extensive hardware equipment. As an alternative to the traditionally used methods we propose an approach of hyperfine transitions’ spectral linewidth measurement. The key characteristic of this method is demonstrated on a set of testing iodine cells. The relationship between laser-induced fluorescence and transition linewidth methods will be presented as well as a summary of the advantages and disadvantages of the proposed technique (in comparison with traditional measurement approaches). PMID:28067834

Numerical investigation of the boundary layer separation in chemical oxygen iodine laser

NASA Astrophysics Data System (ADS)

Huai, Ying; Jia, Shuqin; Wu, Kenan; Jin, Yuqi; Sang, Fengting

2017-11-01

Large eddy simulation is carried out to model the flow process in a supersonic chemical oxygen iodine laser. Unlike the common approaches relying on the tensor representation theory only, the model in the present work is an explicit anisotropy-resolving algebraic Subgrid-scale scalar flux formulation. With an accuracy in capturing the unsteady flow behaviours in the laser. Boundary layer separation initiated by the adverse pressure gradient is identified using Large Eddy Simulation. To quantify the influences of flow boundary layer on the laser performance, the fluid computations coupled with a physical optics loaded cavity model is developed. It has been found that boundary layer separation has a profound effect on the laser outputs due to the introduced shock waves. The F factor of the output beam decreases to 10% of the original one when the boundary transit into turbulence for the setup depicted in the paper. Because the pressure is always greater on the downstream of the boundary layer, there will always be a tendency of boundary separation in the laser. The results inspire designs of the laser to apply positive/passive control methods avoiding the boundary layer perturbation.

Photodissociation Cross Sections and Spectroscopy of Atmospheric Positive Ions

DTIC Science & Technology

1979-03-13

MP 79-1 * ATNR~ e _____________________ CONTRAg T’. NUMNER(s) G. P. Smith, L. C. Lee, P. CCobJ. R. I . DA 9--C- /EPeter o J.: T.1 MoseASy PEFRMN...Photodissociation of positive ions can be an important power-loss process in e -beam and gas discharge lasers, and a genctal model should prove useful...monJel ca.l)olatioa i detibed is, Apm4i 0, 4 PHOTON ENERGY (eV) 1.5 2.0 2.5 3.0 3.5 24k NONO+ E 20E °This work Vanderhoff 0 . -Model calculation 16- z 0_ m

Photodissociation dynamics of the ortho- and para-xylyl radicals

NASA Astrophysics Data System (ADS)

Pachner, Kai; Steglich, Mathias; Hemberger, Patrick; Fischer, Ingo

2017-08-01

The photodissociation dynamics of the C8H9 isomers ortho- and para-xylyl are investigated in a free jet. The xylyl radicals are generated by flash pyrolysis from 2-(2-methylphenyl)- and 2-(4-methylphenyl) ethyl nitrite and are excited into the D3 state. REMPI- spectra show vibronic structure and the origin of the transition is identified at 32 291 cm-1 for the para- and at 32 132 cm-1 for the ortho-isomer. Photofragment H-atom action spectra show bands at the same energy and thus confirm H-atom loss from xylyl radicals. To gain further insight into the photodissociation dynamics, velocity map images of the hydrogen atom photofragments are recorded. Their angular distribution is isotropic and the translational energy release is in agreement with a dissociation to products in their electronic ground state. Photodissociation of para-xylyl leads to the formation of para-xylylene (C8H8), while the data for ortho-xylyl agree much better with the isomer benzocyclobutene as the dominant molecular fragment rather than ortho-xylylene. In computations we identified a new pathway for the reaction ortho-xylyl → benzocyclobutene + H with a barrier of 3.39 eV (27 340 cm-1), which becomes accessible at the employed excitation energy. It proceeds via a combination of scissoring and rotational motion of the -CH2 and -CH3 groups. However, the observed rate constants measured by delaying the excitation and ionization laser with respect to each other are significantly faster than computed ones, indicating intrinsic non-RRKM behaviour. A comparably high value of around 30% of the excess energy is released as translation of the H-atom photofragment.

Photodissociation dynamics of the ortho- and para-xylyl radicals.

PubMed

Pachner, Kai; Steglich, Mathias; Hemberger, Patrick; Fischer, Ingo

2017-08-28

The photodissociation dynamics of the C 8 H 9 isomers ortho- and para-xylyl are investigated in a free jet. The xylyl radicals are generated by flash pyrolysis from 2-(2-methylphenyl)- and 2-(4-methylphenyl) ethyl nitrite and are excited into the D 3 state. REMPI- spectra show vibronic structure and the origin of the transition is identified at 32 291 cm -1 for the para- and at 32 132 cm -1 for the ortho-isomer. Photofragment H-atom action spectra show bands at the same energy and thus confirm H-atom loss from xylyl radicals. To gain further insight into the photodissociation dynamics, velocity map images of the hydrogen atom photofragments are recorded. Their angular distribution is isotropic and the translational energy release is in agreement with a dissociation to products in their electronic ground state. Photodissociation of para-xylyl leads to the formation of para-xylylene (C 8 H 8 ), while the data for ortho-xylyl agree much better with the isomer benzocyclobutene as the dominant molecular fragment rather than ortho-xylylene. In computations we identified a new pathway for the reaction ortho-xylyl → benzocyclobutene + H with a barrier of 3.39 eV (27 340 cm -1 ), which becomes accessible at the employed excitation energy. It proceeds via a combination of scissoring and rotational motion of the -CH 2 and -CH 3 groups. However, the observed rate constants measured by delaying the excitation and ionization laser with respect to each other are significantly faster than computed ones, indicating intrinsic non-RRKM behaviour. A comparably high value of around 30% of the excess energy is released as translation of the H-atom photofragment.

Photodissociation Studies of Metal-Containing Clusters and Complexes

NASA Astrophysics Data System (ADS)

Pilgrim, Jeffrey Scott

1995-01-01

There have been two major areas of investigation for researchers working with laser ablation in molecular beams. The first area is the study of weakly-bound complexes. These complexes are bound by electrostatic interactions. In the present study the weakly bound interactions of the rare gases with the magnesium ion are investigated with electronic spectroscopy. The second major area is the study of metal and metal-containing clusters. Examples of previous investigations are the alkali metal clusters and the fullerenes. The present investigation is on metal -carbon clusters. The so-called metallo-carbohedrenes and metal-carbon nanocrystals are studied. Resonance enhanced photodissociation spectroscopy is used to obtain electronic excitation spectra of the Mg^+-rare gas species in the ultraviolet region. This investigation is facilitated by a reflectron time-of-flight mass spectrometer. The interaction of the rare gas with the metal ion is attributed to a "solvation" of the atomic ion transition. Simple bonding arguments predict that the excited state is more bound than the ground state for these complexes. This will result in a shift of the complex vibronic origin to lower energy from the atomic ion transition. This is exactly what is observed in the experiment with progressively larger shifts for the heavier rare gases. The electronic excitation spectra allow the vibrational frequencies and anharmonicities for these complexes to be obtained for the excited state. In turn, the excited state bond dissociation energies can be determined. Finally, conservation of energy allows calculation of the ground state bond dissociation energies. In the metal-carbon systems the stability of the metallo-carbohedrene, met-car, stoichiometry is shown to extend into the transition period at least to the iron group. Photodissociation with a 532 nm laser causes a loss of metal atoms for met-cars formed with first row transition metals and a loss of metal-carbon units for met

Mechanism of singlet oxygen deactivation in an electric discharge oxygen – iodine laser

DOE Office of Scientific and Technical Information (OSTI.GOV)

Azyazov, V N; Mikheyev, P A; Torbin, A P

2014-12-31

We have determined the influence of the reaction of molecular singlet oxygen with a vibrationally excited ozone molecule O{sub 2}(a {sup 1}Δ) + O{sub 3}(ν) → 2O{sub 2} + O on the removal rate of O{sub 2}(a {sup 1}Δ) in an electric-discharge-driven oxygen – iodine laser. This reaction has been shown to be a major channel of O{sub 2}(a {sup 1}Δ) loss at the output of an electric-discharge singlet oxygen generator. In addition, it can also contribute significantly to the loss of O{sub 2}(a {sup 1}Δ) in the discharge region of the generator. (lasers)

Photoabsorption and photodissociation of molecules important in the interstellar medium

NASA Technical Reports Server (NTRS)

Lee, L. C.

1985-01-01

The photoabsorption and photodissociation cross sections of several interstellar molecules and radicals in the 105 to 210 nm region were measured. The research results accomplished are briefly described. Photoabsorption cross sections of OD and CN, and photoabsorption and photodissociation of HCl, and photoabsorption and photodissociation cross sections of CH3OH are discussed.

LASERS: Efficient chemical oxygen — iodine laser with a high total pressure of the active medium

NASA Astrophysics Data System (ADS)

Zagidullin, M. V.; Nikolaev, V. D.; Svistun, M. I.; Khvatov, N. A.; Heiger, G. D.; Madden, T. J.

2001-01-01

A new concept of obtaining a high total pressure of the active medium of a chemical oxygen — iodine laser (OIL) is proposed and verified. The nozzle unit of the laser consists of the alternating vertical arrays of cylindrical nozzles to produce high-pressure nitrogen jets, plane slotted nozzles for the flow of O2(1Δ) oxygen, and vertical arrays of cylindrical nozzles to inject the N2 — I2 mixture between the first two streams. For a molar chlorine flow rate of 39.2 mmol s-1, the output power was 700 W and the chemical efficiency was 19.7 %. The combined use of the ejector nozzle unit proposed to obtain the active medium and a super-sonic diffuser allows a significant simplification of the ejection system for the exhaust active medium of the OIL.

Optical control of ground-state atomic orbital alignment: Cl(2P3/2) atoms from HCl(v=2,J=1) photodissociation.

PubMed

Sofikitis, Dimitris; Rubio-Lago, Luis; Martin, Marion R; Ankeny Brown, Davida J; Bartlett, Nathaniel C-M; Alexander, Andrew J; Zare, Richard N; Rakitzis, T Peter

2007-10-14

H(35)Cl(v=0,J=0) molecules in a supersonic expansion were excited to the H(35)Cl(v=2,J=1,M=0) state with linearly polarized laser pulses at about 1.7 microm. These rotationally aligned J=1 molecules were then selectively photodissociated with a linearly polarized laser pulse at 220 nm after a time delay, and the velocity-dependent alignment of the (35)Cl((2)P(32)) photofragments was measured using 2+1 REMPI and time-of-flight mass spectrometry. The (35)Cl((2)P(32)) atoms are aligned by two mechanisms: (1) the time-dependent transfer of rotational polarization of the H(35)Cl(v=2,J=1,M=0) molecule to the (35)Cl((2)P(32)) nuclear spin [which is conserved during the photodissociation and thus contributes to the total (35)Cl((2)P(32)) photofragment atomic polarization] and (2) the alignment of the (35)Cl((2)P(32)) electronic polarization resulting from the photoexcitation and dissociation process. The total alignment of the (35)Cl((2)P(32)) photofragments from these two mechanisms was found to vary as a function of time delay between the excitation and the photolysis laser pulses, in agreement with theoretical predictions. We show that the alignment of the ground-state (35)Cl((2)P(32)) atoms, with respect to the photodissociation recoil direction, can be controlled optically. Potential applications include the study of alignment-dependent collision effects.

Photodissociation Studies of Polyatomic Free Radicals

DTIC Science & Technology

1993-08-01

photofragment, that varies with vibrational level, and appears to have a strong J dependence. We are currently in the process of modelling these effects, as well...have also begun to study the photodissociation dynamics of thionyl halides, The photodissociation of thionyl chloride (C12SO) is of interest as a model ...concerted three-body fragmentation mechanism as the primary dissociation channel. A Franck- Condon/golden rule model elucidates the geometry prior to

Studies of oxygen-helium discharges for use in electric oxygen-iodine lasers

NASA Astrophysics Data System (ADS)

Zimmerman, Joseph William

In recent work, the performance of the Electric Oxygen-Iodine Laser (ElectricOIL), developed in partnership by researchers at the University of Illinois and CU Aerospace, has been greatly improved through systematic study of various components of this new laser technology. One major contribution to the advancement of ElectricOIL technology has been the development of electric discharges capable of producing significant flow rates of the precursor electronically-excited molecular oxygen, O2(a1Delta). O2(a 1Delta) serves as an energy reservoir in the laser system, pumping atomic iodine by near-resonant energy transfer producing gain and laser on the I(2P1/2) → I(2P3/2 ) transition at 1315 nm. Initial experimental work with radio-frequency discharges showed the importance of controlling O-atom flow rates to reduce quenching losses of energy stored in O2(a1Delta), and determined proper selection of the helium diluent ratio and specific power deposition (power per O2 flow rate). Further experimental investigations with transverse capacitive radio-frequency discharges in O2/He/NO mixtures in the pressure range of 1-100 Torr and power range of 0.1-1.2 kW have indicated that O2(a1Delta) production is a strong function of geometry (transverse gap), excitation frequency, and pressure. These parameters along with gas flow mixture dictate the current density at which the discharge operates, and its modal characteristics (normal vs. abnormal, homogeneous vs. inhomogeneous). A key result is that to encourage efficient O2(a1Delta) production these parameters should be selected in order to promote a homogeneous (low current density) discharge. The discharge behavior is characterized using terminal current-voltage-characteristics, microwave interferometer measurements, and plasma emission intensity measurements. Numerous spectroscopic measurements of O2(a1Delta), oxygen atoms, and discharge excited states are made in order to describe the discharge performance dependent on

Estimation of the quantum efficiency of the photodissociation of HbO2 and HbCO

NASA Astrophysics Data System (ADS)

Gisbrecht, A. I.; Mamilov, S. A.; Esman, S. S.; Asimov, M. M.

2016-01-01

The paper presents our results on the study of the efficiency of inter-fractional changes in hemoglobin molecules depending on the laser radiation parameters. The evaluation of the quantum efficiency of light interaction in vivo with oxyhemoglobin (HbO2) and carboxyhemoglobin (HbCO) in the blood at wavelengths for 525 and 605 nm is presented. The photodissociation yield of 11% for HbO2 and 79% for HbCO are measured at the wavelength of 525 nm and 10 % for HbO2 and 76 % for HbCO at a wavelength of 605 nm. Thus, the quantum yield of photodissociation of the HbCO is considerably higher, which ensures high efficiency of photodecomposition of the HbCO in the blood. The obtained results can be used in the clinical phototherapy practice for effective treatment of CO poisoning.

Similarity criteria in calculations of the energy characteristics of a cw oxygen - iodine laser

NASA Astrophysics Data System (ADS)

Mezhenin, A. V.; Azyazov, V. N.

2012-12-01

The calculated and experimental data on the energy efficiency of a cw oxygen - iodine laser (OIL) are analysed based on two similarity criteria, namely, on the ratio of the residence time of the gas mixture in the resonator to the characteristic time of extraction of the energy stored in singlet oxygen td and on the gain-to-loss ratio Π. It is shown that the simplified two-level laser model satisfactorily predicts the output characteristics of OILs with a stable resonator at τd <= 7. Efficient energy extraction from the OIL active medium is achieved in the case of τd = 5 - 7, Π = 4 - 8.

Ultrafast photodissociation dynamics of 1,4-diiodobenzene

NASA Astrophysics Data System (ADS)

Stankus, Brian; Zotev, Nikola; Rogers, David M.; Gao, Yan; Odate, Asami; Kirrander, Adam; Weber, Peter M.

2018-05-01

The photodissociation dynamics of 1,4-diiodobenzene is investigated using ultrafast time-resolved photoelectron spectroscopy. Following excitation by laser pulses at 271 nm, the excited-state dynamics is probed by resonance-enhanced multiphoton ionization with 405 nm probe pulses. A progression of Rydberg states, which come into resonance sequentially, provide a fingerprint of the dissociation dynamics of the molecule. The initial excitation decays with a lifetime of 33 ± 4 fs, in good agreement with a previous study. The spectrum is interpreted by reference to ab initio calculations at the CASPT2(18,14) level, including spin-orbit coupling. We propose that both the 5B1 and 6B1 states are excited initially, and based on the calculations, we identify diabatic spin-orbit coupled states corresponding to the main dissociation pathways.

Design and chemical synthesis of iodine-containing molecules for application to solar-pumped I* lasers

NASA Technical Reports Server (NTRS)

Shiner, Christopher S.

1986-01-01

Research is directed toward the design and synthesis of new media for solar-pumped I* lasers. Since the most effective existing lasants are perfluoroalkyl iodides, a strategy was proposed for the development of improved materials of this type with absorption maxima at 300 nm. Absorption spectra were synthesized and measured for prototypical species containing iodine bound to boron, iron, and cobalt.

Photodissociation of the carbon monoxide dication in the (3)Σ(-) manifold: Quantum control simulation towards the C(2+) + O channel.

PubMed

Vranckx, S; Loreau, J; Vaeck, N; Meier, C; Desouter-Lecomte, M

2015-10-28

The photodissociation and laser assisted dissociation of the carbon monoxide dication X(3)Π CO(2+) into the (3)Σ(-) states are investigated. Ab initio electronic structure calculations of the adiabatic potential energy curves, radial nonadiabatic couplings, and dipole moments for the X (3)Π state are performed for 13 excited (3)Σ(-) states of CO(2+). The photodissociation cross section, calculated by time-dependent methods, shows that the C(+) + O(+) channels dominate the process in the studied energy range. The carbon monoxide dication CO(2+) is an interesting candidate for control because it can be produced in a single, long lived, v = 0 vibrational state due to the instability of all the other excited vibrational states of the ground (3)Π electronic state. In a spectral range of about 25 eV, perpendicular transition dipoles couple this (3)Π state to a manifold of (3)Σ(-) excited states leading to numerous C(+) + O(+) channels and a single C(2+) + O channel. This unique channel is used as target for control calculations using local control theory. We illustrate the efficiency of this method in order to find a tailored electric field driving the photodissociation in a manifold of strongly interacting electronic states. The selected local pulses are then concatenated in a sequence inspired by the "laser distillation" strategy. Finally, the local pulse is compared with optimal control theory.

Imaging the photodissociation dynamics of the methyl radical from the 3s and 3pz Rydberg states

PubMed Central

Marggi Poullain, Sonia; Chicharro, David V.; Zanchet, Alexandre; González, Marta G.; Rubio-Lago, Luis; Senent, María L.; García-Vela, Alberto; Bañares, Luis

2016-01-01

The photodissociation dynamics of the methyl radical from the 3s and 3pz Rydberg states have been studied using velocity map and slice ion imaging in combination with pump-probe nanosecond laser pulses. The reported translational energy and angular distributions of the H(2S) photofragment detected by (2+1) REMPI highlight different dissociation mechanisms for the 3s and 3pz Rydberg states. A narrow peak in the translational energy distribution and an anisotropic angular distribution characterizes the fast 3s photodissociation, while for the 3pz state Boltzmann-type translational energy and isotropic angular distributions are found. High level ab initio calculations have been performed in order to elucidate the photodissociation mechanisms from the two Rydberg states and to rationalize the experimental results. The calculated potential energy curves highlight a typical predissociation mechanism for the 3s state, characterized by the coupling between the 3s Rydberg state and a valence repulsive state. On the other hand, the photodissociation on the 3pz state is initiated by a predissociation process due to the coupling between the 3pz Rydberg state and a valence repulsive state and constrained, later on, by two conical intersections that allow the system to relax to lower electronic states. Such mechanism opens different reaction pathways leading to CH2 photofragments in different electronic states and inducing a transfer of energy between translational and internal modes. PMID:27296907

Computer-controlled multi-parameter mapping of 3D compressible flowfields using planar laser-induced iodine fluorescence

NASA Technical Reports Server (NTRS)

Donohue, James M.; Victor, Kenneth G.; Mcdaniel, James C., Jr.

1993-01-01

A computer-controlled technique, using planar laser-induced iodine fluorescence, for measuring complex compressible flowfields is presented. A new laser permits the use of a planar two-line temperature technique so that all parameters can be measured with the laser operated narrowband. Pressure and temperature measurements in a step flowfield show agreement within 10 percent of a CFD model except in regions close to walls. Deviation of near wall temperature measurements from the model was decreased from 21 percent to 12 percent compared to broadband planar temperature measurements. Computer-control of the experiment has been implemented, except for the frequency tuning of the laser. Image data storage and processing has been improved by integrating a workstation into the experimental setup reducing the data reduction time by a factor of 50.

Photodissociation of HBr/LiF(001): A quantum mechanical model

NASA Technical Reports Server (NTRS)

Seideman, Tamar

1993-01-01

The photodissociation dynamics of HBr adsorbed on a LiF(001) surface is studied using time-independent quantum mechanics. The photodissociation lineshape and the Br(P(sub 1/2)-2)/Br(P(sub 3/2)-2) yield ratio are computed and compared with the corresponding quantities for gas phase photodissociation. The angular distribution of the hydrogen photofragments following excitation of adsorbed HBr is computed and found to agree qualitatively with experimental data. The effect of polarization of the photon is illustrated and discussed. The field polarization is found to affect significantly the magnitude of the photodissociation signal but not the angular dependence of the photofragment distribution, in agreement with experiment and in accord with expectations for a strongly aligned adsorbed phase.

Photodissociation of HBr/LiF(001) - A quantum mechanical model

NASA Technical Reports Server (NTRS)

Seideman, Tamar

1993-01-01

The photodissociation dynamics of HBr adsorbed on an LiF(001) surface is studied using time-independent quantum mechanics. The photodissociation line shape and the Br(2P(1/2))/Br(2P(3/2)) yield ratio are computed and compared with the corresponding quantities for gas phase photodissociation. The angular distribution of the hydrogen photofragments following excitation of adsorbed HBr is computed and found to agree qualitatively with experimental data. The effect of polarization of the photon is illustrated and discussed. We find the field polarization to affect significantly the magnitude of the photodissociation signal but not the angular dependence of the photofragment distribution, in agreement with experiment and in accord with expectations for a strongly aligned adsorbed phase.

Combining laser frequency combs and iodine cell calibration techniques for Doppler detection of exoplanets

NASA Astrophysics Data System (ADS)

Cahoy, Kerri; Fischer, Debra; Spronck, Julien; DeMille, David

2010-07-01

Exoplanets can be detected from a time series of stellar spectra by looking for small, periodic shifts in the absorption features that are consistent with Doppler shifts caused by the presence of an exoplanet, or multiple exoplanets, in the system. While hundreds of large exoplanets have already been discovered with the Doppler technique (also called radial velocity), our goal is to improve the measurement precision so that many Earth-like planets can be detected. The smaller mass and longer period of true Earth analogues require the ability to detect a reflex velocity of ~10 cm/s over long time periods. Currently, typical astronomical spectrographs calibrate using either Iodine absorptive cells or Thorium Argon lamps and achieve ~10 m/s precision, with the most stable spectrographs pushing down to ~2 m/s. High velocity precision is currently achieved at HARPS by controlling the thermal and pressure environment of the spectrograph. These environmental controls increase the cost of the spectrograph, and it is not feasible to simply retrofit existing spectrometers. We propose a fiber-fed high precision spectrograph design that combines the existing ~5000-6000 A Iodine calibration system with a high-precision Laser Frequency Comb (LFC) system from ~6000-7000 A that just meets the redward side of the Iodine lines. The scientific motivation for such a system includes: a 1000 A span in the red is currently achievable with LFC systems, combining the two calibration methods increases the wavelength range by a factor of two, and moving redward decreases the "noise" from starspots. The proposed LFC system design employs a fiber laser, tunable serial Fabry-Perot cavity filters to match the resolution of the LFC system to that of standard astronomical spectrographs, and terminal ultrasonic vibration of the multimode fiber for a stable point spread function.

Adsorption of iodine from COIL waste gas on soaked coal-based activated carbon

NASA Astrophysics Data System (ADS)

Zhou, Junbo; Hao, Shan; Gao, Liping

2014-04-01

The chemical oxygen-iodine laser (COIL) has wide application prospects in military, industrial and medical treatment fields as a second generation gas chemical laser to follow the first HF/DF chemical laser. However, a COIL releases large amounts of gas, such as helium, oxygen, chlorine and iodine. Chlorides have a serious corrosive effect on the system, especially iodine vapor crystallization, which seriously endangers the normal use of vacuum systems, and radioactive methyl iodide, which is hazardous to operators and pollutes the environment. The use of soaked coal-based activated carbon as an adsorbent for removing methyl iodine is proposed, while it is proposed that coal-based activated carbon is an effective adsorbent for removing stable iodine. The research conducted in this work shows that iodine residues are less than 0.5 μg ml-1 after the adsorption treatment and the decontamination factor of the coal-based activated carbon for removing stable iodine is more than 1000. Using this method can achieve the purpose of removing harmful iodine, satisfy the requirements for engineering applications, and also be applied to other nuclear power plant flue gas treatments.

Iodine Tagging Velocimetry in a Mach 10 Wake

NASA Technical Reports Server (NTRS)

Balla, Robert Jeffrey

2013-01-01

A variation on molecular tagging velocimetry (MTV) [1] designated iodine tagging velocimetry (ITV) is demonstrated. Molecular iodine is tagged by two-photon absorption using an Argon Fluoride (ArF) excimer laser. A single camera measures fluid displacement using atomic iodine emission at 206 nm. Two examples ofMTVfor cold-flowmeasurements areN2OMTV [2] and Femtosecond Laser Electronic Excitation Tagging [3]. These, like most MTV methods, are designed for atmospheric pressure applications. Neither can be implemented at the low pressures (0.1- 1 Torr) in typical hypersonic wakes. Of all the single-laser/singlecamera MTV approaches, only Nitric-Oxide Planar Laser Induced Fluorescence-based MTV [4] has been successfully demonstrated in a Mach 10 wake. Oxygen quenching limits transit times to 500 ns and accuracy to typically 30%. The present note describes the photophysics of the ITV method. Off-body velocimetry along a line is demonstrated in the aerothermodynamically important and experimentally challenging region of a hypersonic low-pressure near-wake in a Mach 10 air wind tunnel. Transit times up to 10 µs are demonstrated with conservative errors of 10%.

Charge transfer photodissociation of phenol on Ag(111)

NASA Astrophysics Data System (ADS)

Lee, Junseok; Ryu, Sunmin; Ku, Jong Seok; Kim, Seong Keun

2001-12-01

The photochemistry of phenol on Ag(111) has been investigated by post-irradiation temperature programmed desorption (TPD). Ultraviolet (UV) irradiation at 355 and 266 nm was found to affect only the chemisorption layer in direct contact with the metal surface, while leaving the multilayer virtually intact. The main photoinduced reaction was found to be photodissociation of the O-H bond of phenol. Two new peaks were observed at the mass of phenol in the post-irradiation TPD spectrum at 335 K and 455 K. These peaks were assigned to the recombinative desorption of phenoxy with the hydrogen from O-H bond photodissociation and from thermal C-H bond fission, respectively. The photodissociation cross section was measured at different wavelengths and coverages. A charge transfer type photodissociation mechanism was proposed, where hot electrons generated in the substrate by UV photons attach to the affinity level of the adsorbed phenol. The transition to the transient anionic potential then leads to facile dissociation of O-H bond. The affinity level of phenol has been estimated to lie at 3.2-3.5 eV above the Fermi level for the 1 ML case.

Photodissociation dynamics of H2O at 111.5 nm by a vacuum ultraviolet free electron laser

NASA Astrophysics Data System (ADS)

Wang, Heilong; Yu, Yong; Chang, Yao; Su, Shu; Yu, Shengrui; Li, Qinming; Tao, Kai; Ding, Hongli; Yang, Jaiyue; Wang, Guanglei; Che, Li; He, Zhigang; Chen, Zhichao; Wang, Xingan; Zhang, Weiqing; Dai, Dongxu; Wu, Guorong; Yuan, Kaijun; Yang, Xueming

2018-03-01

Photodissociation dynamics of H2O via the F ˜ state at 111.5 nm were investigated using the high resolution H-atom Rydberg "tagging" time-of-flight (TOF) technique, in combination with the tunable vacuum ultraviolet free electron laser at the Dalian Coherent Light Source. The product translational energy distributions and angular distributions in both parallel and perpendicular directions were derived from the recorded TOF spectra. Based on these distributions, the quantum state distributions and angular anisotropy parameters of OH (X) and OH (A) products have been determined. For the OH (A) + H channel, highly rotationally excited OH (A) products have been observed. These products are ascribed to a fast direct dissociation on the B ˜ 1A1 state surface after multi-step internal conversions from the initial excited F ˜ state to the B ˜ state. While for the OH (X) + H channel, very highly rotationally excited OH (X) products with moderate vibrational excitation are revealed and attributed to the dissociation via a nonadiabatic pathway through the well-known two conical intersections between the B ˜ -state and the X ˜ -state surfaces.

Time-dependent infrared emission following photodissociation of nitromethane and chloropicrin.

PubMed

Wade, Elisabeth A; Reak, Kristina E; Li, Sissi L; Clegg, Samuel M; Zou, Peng; Osborn, David L

2006-04-06

Nitromethane (CH(3)NO(2)) and its chlorinated analogue, chloropicrin (CCl(3)NO(2)), were photolyzed at 193, 248, and 266 nm, and the products were observed by time-dependent Fourier transform infrared emission spectroscopy. At 193 and 248 nm, the primary photodissociation pathway for nitromethane was cleavage of the C-N bond to produce CH(3) + NO(2)(A (2)B(2)). At 266 nm, weak emission was observed following photodissociation of nitromethane, but an infrared spectrum could not be obtained. The photodissociation of chloropicrin at 193 nm produced the analogous product channel CCl(3) + NO(2)(A (2)B(2)) in addition to several other product channels. At 248 and 266 nm, only CCl(3) + NO(2)(A (2)B(2)) was observed. The production of phosgene (CCl(2)O) from chloropicrin photodissociation was not observed in this study.

Transient isomers in the photodissociation of bromoiodomethane

NASA Astrophysics Data System (ADS)

Marcellini, Moreno; Nasedkin, Alexandr; Zietz, Burkhard; Petersson, Jonas; Vincent, Jonathan; Palazzetti, Federico; Malmerberg, Erik; Kong, Qingyu; Wulff, Michael; van der Spoel, David; Neutze, Richard; Davidsson, Jan

2018-04-01

The photochemistry of halomethanes is fascinating for the complex cascade reactions toward either the parent or newly synthesized molecules. Here, we address the structural rearrangement of photodissociated CH2IBr in methanol and cyclohexane, probed by time-resolved X-ray scattering in liquid solution. Upon selective laser cleavage of the C-I bond, we follow the reaction cascade of the two geminate geometrical isomers, CH2I-Br and CH2Br-I. Both meta-stable isomers decay on different time scales, mediated by solvent interaction, toward the original parent molecule. We observe the internal rearrangement of CH2Br-I to CH2I-Br in cyclohexane by extending the time window up to 3 μs. We track the photoproduct kinetics of CH2Br-I in methanol solution where only one isomer is observed. The effect of the polarity of solvent on the geminate recombination pathways is discussed.

Threshold kinetics of a solar-simulator-pumped iodine laser

NASA Technical Reports Server (NTRS)

Wilson, J. W.; Lee, Y.; Weaver, W. R.; Humes, D. H.; Lee, J. H.

1984-01-01

A model of the chemical kinetics of the n-C3F7I solar-simulator-pumped iodine laser is utilized to study the major kinetic processes associated with the threshold behavior of this experimental system. Excited-state diffusion to the cell wall is the dominant limiting factor below 5 torr. Excited-state diffusion to the cell wall is the dominant limiting factor below 5 torr. Excited-state recombination with the alkyl radical and quenching by the parent gas control threshold at higher pressures. Treatment of the hyperfine splitting and uncertainty in the pressure broadening are important factors in fixing the threshold level. In spite of scatter in the experimental data caused by instabilities in the simulator high-pressure high-pressure arc, reasonable agreement is achieved between the model and experiment. Model parameters arrived at are within the uncertainty range of values found in the literature.

Oxygen discharge and post-discharge kinetics experiments and modeling for the electric oxygen-iodine laser system.

PubMed

Palla, A D; Zimmerman, J W; Woodard, B S; Carroll, D L; Verdeyen, J T; Lim, T C; Solomon, W C

2007-07-26

Laser oscillation at 1315 nm on the I(2P1/2)-->I(2P3/2) transition of atomic iodine has been obtained by a near resonant energy transfer from O2(a1Delta) produced using a low-pressure oxygen/helium/nitric oxide discharge. In the electric discharge oxygen-iodine laser (ElectricOIL) the discharge production of atomic oxygen, ozone, and other excited species adds levels of complexity to the singlet oxygen generator (SOG) kinetics which are not encountered in a classic purely chemical O2(a1Delta) generation system. The advanced model BLAZE-IV has been introduced to study the energy-transfer laser system dynamics and kinetics. Levels of singlet oxygen, oxygen atoms, and ozone are measured experimentally and compared with calculations. The new BLAZE-IV model is in reasonable agreement with O3, O atom, and gas temperature measurements but is under-predicting the increase in O2(a1Delta) concentration resulting from the presence of NO in the discharge and under-predicting the O2(b1Sigma) concentrations. A key conclusion is that the removal of oxygen atoms by NOX species leads to a significant increase in O2(a1Delta) concentrations downstream of the discharge in part via a recycling process; however, there are still some important processes related to the NOX discharge kinetics that are missing from the present modeling. Further, the removal of oxygen atoms dramatically inhibits the production of ozone in the downstream kinetics.

Solar pumped laser technology options for space power transmission

NASA Technical Reports Server (NTRS)

Conway, E. J.

1986-01-01

An overview of long-range options for in-space laser power transmission is presented. The focus is on the new technology and research status of solar-pumped lasers and their solar concentration needs. The laser options include gas photodissociation lasers, optically-pumped solid-state lasers, and blackbody-pumped transfer lasers. The paper concludes with a summary of current research thrusts.

Laser induced photoluminescence spectroscopy of cometary radicals

NASA Technical Reports Server (NTRS)

Jackson, W. M.; Cody, R. J.; Sabety-Dzvonik, M.

1976-01-01

Flash photolysis together with laser excitation of the product fragments was used in laboratory studies of cometary radicals. The LIPS method has been applied to the CN radical to determine: (1) Radiative lifetimes of individual rotational levels in the zeroth vibrational level of the B state; (2) energy partitioning during photodissociation of C2N2; and (3) vibrational and rotational excitation during formation of CN radicals in the photodissociation of dicyanoacetylene.

Photodissociation of CS from Excited Rovibrational Levels

NASA Astrophysics Data System (ADS)

Pattillo, R. J.; Cieszewski, R.; Stancil, P. C.; Forrey, R. C.; Babb, J. F.; McCann, J. F.; McLaughlin, B. M.

2018-05-01

Accurate photodissociation cross sections have been computed for transitions from the X 1Σ+ ground electronic state of CS to six low-lying excited electronic states. New ab initio potential curves and transition dipole moment functions have been obtained for these computations using the multi-reference configuration interaction approach with the Davidson correction (MRCI+Q) and aug-cc-pV6Z basis sets. State-resolved cross sections have been computed for transitions from nearly the full range of rovibrational levels of the X 1Σ+ state and for photon wavelengths ranging from 500 Å to threshold. Destruction of CS via predissociation in highly excited electronic states originating from the rovibrational ground state is found to be unimportant. Photodissociation cross sections are presented for temperatures in the range between 1000 and 10,000 K, where a Boltzmann distribution of initial rovibrational levels is assumed. Applications of the current computations to various astrophysical environments are briefly discussed focusing on photodissociation rates due to the standard interstellar and blackbody radiation fields.

A velocity-map imaging study of methyl non-resonant multiphoton ionization from the photodissociation of CH3I in the A-band

PubMed Central

Poullain, Sonia Marggi; Chicharro, David V.; Rubio-Lago, Luis; García-Vela, Alberto

2017-01-01

Chemical reaction dynamics and, particularly, photodissociation in the gas phase are generally studied using pump–probe schemes where a first laser pulse induces the process under study and a second one detects the produced fragments. Providing an efficient detection of ro-vibrationally state-selected photofragments, the resonance enhanced multiphoton ionization (REMPI) technique is, without question, the most popular approach used for the probe step, while non-resonant multiphoton ionization (NRMPI) detection of the products is scarce. The main goal of this work is to test the sensitivity of the NRMPI technique to fragment vibrational distributions arising from molecular photodissociation processes. We revisit the well-known process of methyl iodide photodissociation in the A-band at around 280 nm, using the velocity-map imaging technique in conjunction with NRMPI of the methyl fragment. The detection wavelength, carefully selected to avoid any REMPI transition, was scanned between 325 and 335 nm seeking correlations between the different observables—the product vibrational, translational and angular distributions—and the excitation wavelength of the probe laser pulse. The experimental results have been discussed on the base of quantum dynamics calculations of photofragment vibrational populations carried out on available ab initio potential-energy surfaces using a four-dimensional model. This article is part of the themed issue ‘Theoretical and computational studies of non-equilibrium and non-statistical dynamics in the gas phase, in the condensed phase and at interfaces’. PMID:28320907

Dissociation of iodine molecules and singlet oxygen generation in O2 - I2 mixture induced by 1315-nm laser radiation

NASA Astrophysics Data System (ADS)

Zagidullin, M. V.; Khvatov, N. A.; Malyshev, M. S.; Azyazov, V. N.

2017-11-01

It is observed that laser light at a wavelength of 1315 nm induces continuous stable fluorescence at the O2(b1Σ → X3Σ) and I2(B3Πu → X1Σ) bands in a O2 - I2 mixture preliminarily irradiated at a wavelength of 532 nm to achieve partial photolysis of iodine molecules. This testifies to generation of iodine atoms and excited O2(a1Δ), O2(b1Σ), and I2(B3Πu) molecules in the O2 - I2 mixture under irradiation at 1315 nm.

Investigation of Singly Ionized Iodine Spectroscopy in Support of Electrostatic Propulsion Diagnostics Development

DTIC Science & Technology

2012-07-02

from complex user interactions due to the use of liquid lasing medium with finite lifetime. Solid state lasers such as titanium sapphire (Ti:Sapphire...transitions for laser -induced fluorescence of an accelerated atomic iodine singly charged ion (I+). While the second spectrum of iodine has been analyzed...diagnostics tools, such as laser -induced fluorescence (LIF), to examine the plasma acceleration within an electro-static plasma propulsion thruster. While

Observation of rotational revivals for iodine molecules in helium droplets using a near-adiabatic laser pulse

NASA Astrophysics Data System (ADS)

Shepperson, Benjamin; Chatterley, Adam S.; Christiansen, Lars; Søndergaard, Anders A.; Stapelfeldt, Henrik

2018-01-01

A 160-ps near-Gaussian, linearly polarized laser pulse is used to align iodine (I2) molecules embedded in helium nanodroplets. The rise time of the laser pulse is sufficiently long and smooth that the alignment, characterized by , behaves adiabatically during the pulse turnon. However, after the laser pulse has turned off stays above 0.50 and a recurrence structure occurs ˜650 ps later. Measurements on isolated (I2) molecules with identical laser pulses are used to identify, through analysis of the observed half- and full-rotational revivals, that the nonadiabatic postpulse alignment dynamics results from a mild truncation of the trailing edge of the laser pulse. This truncation establishes a well-defined starting time for coherent rotation, which leads to the revival structures observed both for isolated molecules and molecules in He droplets. In the latter case the time-dependent trace recorded here is compared to that obtained previously for a 450-fs alignment pulse. It is found that the observed revivals are very similar.

Photodissociation of methyl formate: Conical intersections, roaming and triple fragmentation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lin, King-Chuen; Tsai, Po-Yu; Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 106, Taiwan

2015-12-31

The photodissociation channels of methyl formate have been extensively investigated by two different advanced experimental techniques, ion imaging and Fourier-Transform-Infrared emission spectroscopy, combined with quantum chemical calculations and molecular dynamics simulations. Our aim is to characterize the role of alternative routes to the conventional transition-state mediated pathway: the roaming and the triple fragmentation processes. The photolysis experiments, carried out at a range of laser wavelengths in the vicinity of the triple fragmentation threshold, beside the simulation of large bunches of classical trajectories with different initial conditions, have shown that both mechanisms share a common path that involves a conical intersectionmore » during the relaxation process from the electronic excited state S{sub 1} to the ground state S{sub 0}.« less

Photodissociation dynamics and spectroscopy of free radical combustion intermediates

DOE Office of Scientific and Technical Information (OSTI.GOV)

Osborn, David Lewis

1996-12-01

The photodissociation spectroscopy and dynamics of free radicals is studied by the technique of fast beam photofragment translational spectroscopy. Photodetachment of internally cold, mass-selected negative ions produces a clean source of radicals, which are subsequently dissociated and detected. The photofragment yield as a function of photon energy is obtained, mapping out the dissociative and predissociative electronic states of the radical. In addition, the photodissociation dynamics, product branching ratios, and bond energies are probed at fixed photon energies by measuring the translational energy, P(E T), and angular distribution of the recoiling fragments using a time- and position-sensitive detector. Ab initio calculationsmore » are combined with dynamical and statistical models to interpret the observed data. The photodissociation of three prototypical hydrocarbon combustion intermediates forms the core of this work.« less

Photodissociation of the CH3Cl/+/ and N2O/+/ cations.

NASA Technical Reports Server (NTRS)

Dunbar, R. C.

1971-01-01

Use of the ion cyclotron resonance (icr) technique to observe the photodissociation of the cations CH3Cl(+) and N2O(+) in the gas phase. Ions were trapped in the icr cell for periods of the order of seconds, which permitted the photodissociation process to be observed with wavelength-selected light. A cyclotron resonance ejection technique was employed to show that CH3Cl(+) ions were being dissociated rather than the CH3ClH(+) ions which were also present. The photodissociation cross section for N2O(+) was found to be without strong wavelength dependence between 4000 and 6500 A. The cross section for CH3Cl(+) showed a large peak at 3150 A. Possible assignments of this peak are considered, and it is suggested that a photodissociation occurs through an ion excitation involving a change in occupation of the bonding or antibonding orbitals of the C-Cl bond.

Photodissociation of nitromethane cluster anions.

PubMed

Goebbert, Daniel J; Khuseynov, Dmitry; Sanov, Andrei

2010-08-28

Three types of anionic fragments are observed in the photodissociation of nitromethane cluster anions, (CH(3)NO(2))(n)(-), n=1-6, at 355 nm: NO(2)(-)(CH(3)NO(2))(k), (CH(3)NO(2))(k)(-), and OH(-) (kphotodissociation of CH(3)NO(2)(-) requires lower energy photons because the photochemically active electron occupies a high energy pi* orbital (which is vacant in the neutral). Although the electronic states in the photodissociation of CH(3)NO(2) and CH(3)NO(2)(-) are different, the major fragments, CH(3)+NO(2) and CH(3)+NO(2)(-), respectively, both form via C-N bond cleavage.

Tuning the ultrafast photodissociation dynamics of CH3Br on ultrathin MgO films by reducing the layer thickness to the 2D limit

NASA Astrophysics Data System (ADS)

Vaida, Mihai E.; Bernhardt, Thorsten M.

2017-11-01

The femtosecond-laser induced photodissociation of CH3Br adsorbed at sub-monolayer coverage on a solid surface was investigated by time-resolved pump-probe mass spectrometry. To tune the interaction of the CH3Br molecules with the substrate, an Mo(1 0 0) surface was covered with ultrathin insulating MgO layers of variable thickness. By gradually decreasing the magnesia layer thickness to the 2D limit the photodissociation dynamics observed by detection of the methyl fragment indicates an energetic lowering of the relevant methyl bromide excited states due to the increasing spatial proximity of the metallic support. Potential orientational effects of the methyl bromide adsorption geometry are also considered.

The efficiency of photodissociation for molecules in interstellar ices

NASA Astrophysics Data System (ADS)

Kalvāns, J.

2018-05-01

Processing by interstellar photons affects the composition of the icy mantles on interstellar grains. The rate of photodissociation in solids differs from that of molecules in the gas phase. The aim of this work was to determine an average, general ratio between photodissociation coefficients for molecules in ice and gas. A 1D astrochemical model was utilized to simulate the chemical composition for a line of sight through a collapsing interstellar cloud core, whose interstellar extinction changes with time. At different extinctions, the calculated column densities of icy carbon oxides and ammonia (relative to water ice) were compared to observations. The latter were taken from literature data of background stars sampling ices in molecular clouds. The best-fit value for the solid/gas photodissociation coefficient ratio was found to be ≈0.3. In other words, gas-phase photodissociation rate coefficients have to be reduced by a factor of 0.3 before applying them to icy species. A crucial part of the model is a proper inclusion of cosmic-ray induced desorption. Observations sampling gas with total extinctions in excess of ≈22 mag were found to be uncorrelated to modelling results, possibly because of grains being covered with non-polar molecules.

Control of Ultracold Photodissociation with Magnetic Fields

NASA Astrophysics Data System (ADS)

McDonald, M.; Majewska, I.; Lee, C.-H.; Kondov, S. S.; McGuyer, B. H.; Moszynski, R.; Zelevinsky, T.

2018-01-01

Photodissociation of a molecule produces a spatial distribution of photofragments determined by the molecular structure and the characteristics of the dissociating light. Performing this basic reaction at ultracold temperatures allows its quantum mechanical features to dominate. In this regime, weak applied fields can be used to control the reaction. Here, we photodissociate ultracold diatomic strontium in magnetic fields below 10 G and observe striking changes in photofragment angular distributions. The observations are in excellent agreement with a multichannel quantum chemistry model that includes nonadiabatic effects and predicts strong mixing of partial waves in the photofragment energy continuum. The experiment is enabled by precise quantum-state control of the molecules.

Laser source for dimensional metrology: investigation of an iodine stabilized system based on narrow linewidth 633 nm DBR diode

NASA Astrophysics Data System (ADS)

Rerucha, Simon; Yacoot, Andrew; Pham, Tuan M.; Cizek, Martin; Hucl, Vaclav; Lazar, Josef; Cip, Ondrej

2017-04-01

We demonstrated that an iodine stabilized distributed Bragg reflector (DBR) diode based laser system lasing at a wavelength in close proximity to λ =633 nm could be used as an alternative laser source to the helium-neon lasers in both scientific and industrial metrology. This yields additional advantages besides the optical frequency stability and coherence: inherent traceability, wider optical frequency tuning range, higher output power and high frequency modulation capability. We experimentally investigated the characteristics of the laser source in two major steps: first using a wavelength meter referenced to a frequency comb controlled with a hydrogen maser and then on an interferometric optical bench testbed where we compared the performance of the laser system with that of a traditional frequency stabilized He-Ne laser. The results indicate that DBR diode laser system provides a good laser source for applications in dimensional (nano)metrology, especially in conjunction with novel interferometric detection methods exploiting high frequency modulation or multiaxis measurement systems.

An iodine hypersonic wind tunnel for the study of nonequilibrium reacting flows

NASA Technical Reports Server (NTRS)

Pham-Van-diep, G. C.; Muntz, E. P.; Weaver, D. P.; Dewitt, T. G.; Bradley, M. K.; Erwin, D. A.; Kunc, J. A.

1992-01-01

A pilot scale hypersonic wind tunnel operating on pure iodine vapor has been designed and tested. The wind tunnel operates intermittently with a run phase lasting approximately 20 minutes. Successful recirculation of the iodine used during the run phase has been achieved but can be improved. Relevant issues regarding the full scale facility's design and operation, and the use of iodine as a working gas are discussed. Continuous wave laser induced fluorescence was used to monitor number densities within the plume flowfield, while pulsed laser induced fluorescence was used in an initial attempt to measure vibrational energy state population distributions. Preliminary nozzle flow calculations based on finite rate chemistry are presented.

Directly solar-pumped iodine laser for beamed power transmission in space

NASA Technical Reports Server (NTRS)

Choi, S. H.; Meador, W. E.; Lee, J. H.

1992-01-01

A new approach for development of a 50-kW directly solar-pumped iodine laser (DSPIL) system as a space-based power station was made using a confocal unstable resonator (CUR). The CUR-based DSPIL has advantages, such as performance enhancement, reduction of total mass, and simplicity which alleviates the complexities inherent in the previous system, master oscillator/power amplifier (MOPA) configurations. In this design, a single CUR-based DSPIL with 50-kW output power was defined and compared to the MOPA-based DSPIL. Integration of multiple modules for power requirements more than 50-kW is physically and structurally a sound approach as compared to building a single large system. An integrated system of multiple modules can respond to various mission power requirements by combining and aiming the coherent beams at the user's receiver.

Performance Characteristics of Jet-type Generator of Singlet Oxygen for Supersonic Chemical Oxygen-Iodine Laser*1

NASA Astrophysics Data System (ADS)

Kodymová, Jarmila; Špalek, Otomar

1998-01-01

A jet-type singlet oxygen generator based on a gas-liquid chemical reaction yielding singlet oxygen, O2(1Δ g), for pumping the supersonic chemical oxygen-iodine laser was investigated. In addition to O2(1Δ g) and residual chlorine concentrations, a content of water formed during O2(1Δ g) generation was estimated (because of its detrimental effect on lasing) in gas flowing from the generator to the laser active region. The experimental conditions were determined under which an effect of liquid droplets escaping from the generator was negligible, and accordingly, a content of water vapour was suppressed to a value corresponding to the saturated water vapour pressure. It was also proved that a reduction in the relative water content, and a consequent increase in the laser output power, could be achieved by increasing peroxide and hydroxide concentration in the generator liquid, and by decreasing a liquid temperature and a total pressure in the generator.

A 50-kW Module Power Station of Directly Solar-Pumped Iodine Laser

NASA Technical Reports Server (NTRS)

Choi, S. H.; Lee, J. H.; Meador, W. E.; Conway, E. J.

1997-01-01

The conceptual design of a 50 kW Directly Solar-Pumped Iodine Laser (DSPIL) module was developed for a space-based power station which transmits its coherent-beam power to users such as the moon, Martian rovers, or other satellites with large (greater than 25 kW) electric power requirements. Integration of multiple modules would provide an amount of power that exceeds the power of a single module by combining and directing the coherent beams to the user's receiver. The model developed for the DSPIL system conservatively predicts the laser output power (50 kW) that appears much less than the laser output (93 kW) obtained from the gain volume ratio extrapolation of experimental data. The difference in laser outputs may be attributed to reflector configurations adopted in both design and experiment. Even though the photon absorption by multiple reflections in experimental cavity setup was more efficient, the maximum secondary absorption amounts to be only 24.7 percent of the primary. However, the gain volume ratio shows 86 percent more power output than theoretical estimation that is roughly 60 percent more than the contribution by the secondary absorption. Such a difference indicates that the theoretical model adopted in the study underestimates the overall performance of the DSPIL. This fact may tolerate more flexible and radical selection of design parameters than used in this design study. The design achieves an overall specific power of approximately 5 W/kg and total mass of 10 metric tons.

Photodissociation pathways and lifetimes of protonated peptides and their dimers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Aravind, G.; Klaerke, B.; Rajput, J.

2012-01-07

Photodissociation lifetimes and fragment channels of gas-phase, protonated YA{sub n} (n = 1,2) peptides and their dimers were measured with 266 nm photons. The protonated monomers were found to have a fast dissociation channel with an exponential lifetime of {approx}200 ns while the protonated dimers show an additional slow dissociation component with a lifetime of {approx}2 {mu}s. Laser power dependence measurements enabled us to ascribe the fast channel in the monomer and the slow channel in the dimer to a one-photon process, whereas the fast dimer channel is from a two-photon process. The slow (1 photon) dissociation channel in themore » dimer was found to result in cleavage of the H-bonds after energy transfer through these H-bonds. In general, the dissociation of these protonated peptides is non-prompt and the decay time was found to increase with the size of the peptides. Quantum RRKM calculations of the microcanonical rate constants also confirmed a statistical nature of the photodissociation processes in the dipeptide monomers and dimers. The classical RRKM expression gives a rate constant as an analytical function of the number of active vibrational modes in the system, estimated separately on the basis of the equipartition theorem. It demonstrates encouraging results in predicting fragmentation lifetimes of protonated peptides. Finally, we present the first experimental evidence for a photo-induced conversion of tyrosine-containing peptides into monocyclic aromatic hydrocarbon along with a formamide molecule both found in space.« less

A computational fluid dynamics simulation of a supersonic chemical oxygen-iodine laser

NASA Astrophysics Data System (ADS)

Waichman, K.; Rybalkin, V.; Katz, A.; Dahan, Z.; Barmashenko, B. D.; Rosenwaks, S.

2007-05-01

The dissociation of I II molecules at the optical axis of a supersonic chemical oxygen-iodine laser (COIL) was studied via detailed measurements and three dimensional computational fluid dynamics calculations. Comparing the measurements and the calculations enabled critical examination of previously proposed dissociation mechanisms and suggestion of a mechanism consistent with the experimental and theoretical results. The gain, I II dissociation fraction and temperature at the optical axis, calculated using Heidner's model (R.F. Heidner III et al., J. Phys. Chem. 87, 2348 (1983)), are much lower than those measured experimentally. Agreement with the experimental results was reached by using Heidner's model supplemented by Azyazov-Heaven's model (V.N. Azyazov and M.C. Heaven, AIAA J. 44, 1593 (2006)) where I II(A') and vibrationally excited O II(a1Δ) are significant dissociation intermediates.

Radical Rearrangement Chemistry in Ultraviolet Photodissociation of Iodotyrosine Systems: Insights from Metastable Dissociation, Infrared Ion Spectroscopy, and Reaction Pathway Calculations.

PubMed

Ranka, Karnamohit; Zhao, Ning; Yu, Long; Stanton, John F; Polfer, Nicolas C

2018-05-29

We report on the ultraviolet photodissociation (UVPD) chemistry of protonated tyrosine, iodotyrosine, and diiodotyrosine. Distonic loss of the iodine creates a high-energy radical at the aromatic ring that engages in hydrogen/proton rearrangement chemistry. Based on UVPD kinetics measurements, the appearance of this radical is coincident with the UV irradiation pulse (8 ns). Conversely, sequential UVPD product ions exhibit metastable decay on ca. 100 ns timescales. Infrared ion spectroscopy is capable of confirming putative structures of the rearrangement products as proton transfers from the imine and β-carbon hydrogens. Potential energy surfaces for the various reaction pathways indicate that the rearrangement chemistry is highly complex, compatible with a cascade of rearrangements, and that there is no preferred rearrangement pathway even in small molecular systems like these. Graphical Abstract.

Photodissociation of the carbon monoxide dication in the {sup 3}Σ{sup −} manifold: Quantum control simulation towards the C{sup 2+} + O channel

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vranckx, S.; Laboratoire de Chimie Physique; Loreau, J.

The photodissociation and laser assisted dissociation of the carbon monoxide dication X{sup 3}Π CO{sup 2+} into the {sup 3}Σ{sup −} states are investigated. Ab initio electronic structure calculations of the adiabatic potential energy curves, radial nonadiabatic couplings, and dipole moments for the X {sup 3}Π state are performed for 13 excited {sup 3}Σ{sup −} states of CO{sup 2+}. The photodissociation cross section, calculated by time-dependent methods, shows that the C{sup +} + O{sup +} channels dominate the process in the studied energy range. The carbon monoxide dication CO{sup 2+} is an interesting candidate for control because it can be producedmore » in a single, long lived, v = 0 vibrational state due to the instability of all the other excited vibrational states of the ground {sup 3}Π electronic state. In a spectral range of about 25 eV, perpendicular transition dipoles couple this {sup 3}Π state to a manifold of {sup 3}Σ{sup −} excited states leading to numerous C{sup +} + O{sup +} channels and a single C{sup 2+} + O channel. This unique channel is used as target for control calculations using local control theory. We illustrate the efficiency of this method in order to find a tailored electric field driving the photodissociation in a manifold of strongly interacting electronic states. The selected local pulses are then concatenated in a sequence inspired by the “laser distillation” strategy. Finally, the local pulse is compared with optimal control theory.« less

Does photodissociation of molecular oxygen from myoglobin and hemoglobin yield singlet oxygen?

PubMed

Lepeshkevich, Sergei V; Stasheuski, Alexander S; Parkhats, Marina V; Galievsky, Victor A; Dzhagarov, Boris M

2013-03-05

Time-resolved luminescence measurements in the near-infrared region indicate that photodissociation of molecular oxygen from myoglobin and hemoglobin does not produce detectable quantities of singlet oxygen. A simple and highly sensitive method of luminescence quantification is developed and used to determine the upper limit for the quantum yield of singlet oxygen production. The proposed method was preliminarily evaluated using model data sets and confirmed with experimental data for aqueous solutions of 5,10,15,20-tetrakis(4-N-methylpyridyl) porphyrin. A general procedure for error estimation is suggested. The method is shown to provide a determination of the integral luminescence intensity in a wide range of values even for kinetics with extremely low signal-to-noise ratio. The present experimental data do not deny the possibility of singlet oxygen generation during the photodissociation of molecular oxygen from myoglobin and hemoglobin. However, the photodissociation is not efficient to yield singlet oxygen escaped from the proteins into the surrounding medium. The upper limits for the quantum yields of singlet oxygen production in the surrounding medium after the photodissociation for oxyhemoglobin and oxymyoglobin do not exceed 3.4×10(-3) and 2.3×10(-3), respectively. On the average, no more than one molecule of singlet oxygen from every hundred photodissociated oxygen molecules can succeed in escaping from the protein matrix. Copyright © 2013 Elsevier B.V. All rights reserved.

Photodissociation spectroscopy of the Mg + -CO2 complex and its isotopic analogs

NASA Astrophysics Data System (ADS)

Yeh, C. S.; Willey, K. F.; Robbins, D. L.; Pilgrim, J. S.; Duncan, M. A.

1993-02-01

Mg+-CO2 ion-molecule cluster complexes are produced by laser vaporization in a pulsed nozzle cluster source. The vibronic spectroscopy in these complexes is studied with mass-selected photodissociation spectroscopy in a reflectron time-of-flight mass spectrometer. Two excited electronic states are observed (2) 2Σ+ and 2Π. The 2Π state has a vibrational progression in the metal-CO2 stretching mode (ωe'=381.8 cm-1). The complexes are linear (Mg+-OCO) and are bound by the charge-quadrupole interaction. The dissociation energy (D0`) is 14.7 kcal/mol. Corresponding spectra are measured for each of the 24, 25, and 26 isotopes of magnesium. These results are compared to theoretical predictions made by Bauschlicher and co-workers.

Ultraviolet photodissociation action spectroscopy of the N-pyridinium cation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hansen, Christopher S., E-mail: csh297@uowmail.edu.au; Trevitt, Adam J., E-mail: adamt@uow.edu.au; Blanksby, Stephen J.

2015-01-07

The S{sub 1}←S{sub 0} electronic transition of the N-pyridinium ion (C{sub 5}H{sub 5}NH{sup +}) is investigated using ultraviolet photodissociation (PD) spectroscopy of the bare ion and also the N{sub 2}-tagged complex. Gas-phase N-pyridinium ions photodissociate by the loss of molecular hydrogen (H{sub 2}) in the photon energy range 37 000–45 000 cm{sup −1} with structurally diagnostic ion-molecule reactions identifying the 2-pyridinylium ion as the exclusive co-product. The photodissociation action spectra reveal vibronic details that, with the aid of electronic structure calculations, support the proposal that dissociation occurs through an intramolecular rearrangement on the ground electronic state following internal conversion. Quantum chemical calculationsmore » are used to analyze the measured spectra. Most of the vibronic features are attributed to progressions of totally symmetric ring deformation modes and out-of-plane modes active in the isomerization of the planar excited state towards the non-planar excited state global minimum.« less

Experimental investigation of a supersonic swept ramp injector using laser-induced iodine fluorescence

NASA Technical Reports Server (NTRS)

Hartfield, Roy J.; Hollo, Steven D.; Mcdaniel, James C.

1990-01-01

Planar measurements of injectant mole fraction and temperature have been conducted in a nonreacting supersonic combustor configured with underexpanded injection in the base of a swept ramp. The temperature measurements were conducted with a Mach 2 test section inlet in streamwise planes perpendicular to the test section wall on which the ramp was mounted. Injection concentration measurements, conducted in cross flow planes with both Mach 2 and Mach 2.9 free stream conditions, dramatically illustrate the domination of the mixing process by streamwise vorticity generated by the ramp. These measurements, conducted using a nonintrusive optical technique (laser-induced iodine fluorescence), provide an accurate and extensive experimental data base for the validation of computation fluid dynamic codes for the calculation of highly three-dimensional supersonic combustor flow fields.

Lone-pair interactions and photodissociation of compressed nitrogen trifluoride

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kurzydłowski, D., E-mail: dkurzydlowski@uw.edu.pl; Department of Biogeochemistry, Max Planck Institute for Chemistry, 55128 Mainz; Wang, H. B.

2014-08-14

High-pressure behavior of nitrogen trifluoride (NF{sub 3}) was investigated by Raman and IR spectroscopy at pressures up to 55 GPa and room temperature, as well as by periodic calculations up to 100 GPa. Experimentally, we find three solid-solid phase transitions at 9, 18, and 39.5 GPa. Vibrational spectroscopy indicates that in all observed phases NF{sub 3} remains in the molecular form, in contrast to the behavior of compressed ammonia. This finding is confirmed by density functional theory calculations, which also indicate that the phase transitions of compressed NF{sub 3} are governed by the interplay between lone‑pair interactions and efficient moleculemore » packing. Although nitrogen trifluoride is molecular in the whole pressure range studied, we show that it can be photodissociated by mid-IR laser radiation. This finding paves the way for the use of NF{sub 3} as an oxidizing and fluorinating agent in high-pressure reactions.« less

Photodissociable dimer reduction products of 2-thiopyrimidine derivatives.

PubMed Central

Wrona, M; Giziewicz, J; Shugar, D

1975-01-01

Both 4,6-dimethyl-2-thipyrimidine and its 1-methyl derivative undergo polarographic reduction in aqueous medium, via a 1e/1H+ reduction to a free radical which rapidly dimerizes to products isolates and identified as 4,4'-bis-(4,6-dimethyl-3,4-dihydropyrimidin-2-thione) and the corresponding 1-methyl dimer. The dimers may be oxidized electrolytically to regenerate the parent monomers. Both dimers also undergo photodissociation to quantitatively regenerate the parent monomers, in high quantum yield, 0.23 and 0.35 M/Einstein. The correlation between electrochemical and photochemical reductions of 2-thiopyrimidines are discussed, as well as the significance of the dimer photodissociation reactions in relation to nucleic acid photochemistry. PMID:28516

High-Resolution Photoionization, Photoelectron and Photodissociation Studies. Determination of Accurate Energetic and Spectroscopic Database for Combustion Radicals and Molecules

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ng, Cheuk-Yiu

2016-04-25

The main goal of this research program was to obtain accurate thermochemical and spectroscopic data, such as ionization energies (IEs), 0 K bond dissociation energies, 0 K heats of formation, and spectroscopic constants for radicals and molecules and their ions of relevance to combustion chemistry. Two unique, generally applicable vacuum ultraviolet (VUV) laser photoion-photoelectron apparatuses have been developed in our group, which have used for high-resolution photoionization, photoelectron, and photodissociation studies for many small molecules of combustion relevance.

Singlet oxygen generation in gas discharge for oxygen-iodine laser pumping

NASA Astrophysics Data System (ADS)

Lopaev, D. V.; Braginsky, O. V.; Klopovsky, K. S.; Kovalev, A. S.; Mankelevich, Yu. A.; Popov, N. A.; Rakhimov, A. T.; Rakhimova, T. V.; Vasilieva, A. N.

2004-09-01

The possibility of development of effective discharged singlet oxygen (SO) generator (DSOG) for oxygen-iodine laser (OIL) is studied in detail. Researches of kinetics of oxygen atoms and oxygen molecules in the lowest metastable singlet states have been carried out in the different discharges and its afterglow (DC discharges, E-beam controlled discharge and RF discharges) in both CW and pulsed mode in a wide range of conditions (pressures, gas mixtures, energy deposits etc.). The models developed for all the discharges have allowed us to analyze SO generation and loss mechanisms and to find out the key-parameters controlling the highest SO yield. It is shown that in addition to spatial plasma uniformity at low E/N and high specific energy deposit per oxygen molecule, DSOG must be oxygen atom free to avoid fast three-body quenching of SO by atomic oxygen with increasing pressure and thereby to provide pressure scaling (in tens Torrs) for applying to real OIL systems.

Effect of the solution temperature in a singlet-oxygen generator on the formation of active medium in an ejector oxygen - iodine laser

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zagidullin, M V; Nikolaev, V D; Svistun, M I

2002-02-28

The influence of the solution temperature in a singlet-oxygen generator on the formation of the active medium in the ejector oxygen - iodine laser is investigated. The following parameters of the active medium at the solution temperature -20{sup 0}C are obtained: the gain is 7.2 x 10{sup -3} cm{sup -1}, the Mach number is M=2, the temperature is 205 K, and the static pressure is 9.3 mmHg. As the solution temperature is increased to -4{sup 0}C, the gain decreases to 5 x 10{sup 3} cm{sup -1}, the Mach number decreases to 1.78, while the temperature and the static pressure increasemore » to 241 K and 10.7 mmHg, respectively. As the solution temperature increases from -20 to -4{sup 0}C, the losses in O{sub 2}({sup 1}{Delta}) increase by less than 20%, while the dissociation efficiency of molecular iodine decreases by less than 21%. (lasers, active media)« less

Flowfield measurements in a model scramjet combustion using laser-induced iodine fluorescence

NASA Technical Reports Server (NTRS)

Mcdaniel, J. C., Jr.

1984-01-01

Preliminary designs were completed for an iodine mixing chamber and the optical setup to be used with a modified wind tunnel in obtaining accurate, spatially resolved measurements of variables in the flowfield of a model nonreacting scramjet combustor. Schematics of the iodine-seeded wind tunnel and a sketch of the charcoal filter for removing the iodine are included along with a cutaway section of the laboratory.

Imaging charge transfer in a cation-π system: velocity-map imaging of Ag(+)(benzene) photodissociation.

PubMed

Maner, Jonathon A; Mauney, Daniel T; Duncan, Michael A

2015-11-19

Ag(+)(benzene) complexes are generated in the gas phase by laser vaporization and mass selected in a time-of-flight spectrometer. UV laser excitation at either 355 or 266 nm results in dissociative charge transfer (DCT), leading to neutral silver atom and benzene cation products. Kinetic energy release in translationally hot benzene cations is detected using a new instrument designed for photofragment imaging of mass-selected ions. Velocity-map imaging and slice imaging techniques are employed. In addition to the expected translational energy release, DCT of Ag(+)(benzene) produces a distribution of internally hot benzene cations. Compared with experiments at 355 nm, 266 nm excitation produces only slightly higher translational excitation and a much greater fraction of internally hot benzene ions. The maximum kinetic energy release in the photodissociation sets an upper limit on the Ag(+)(benzene) dissociation energy of 32.8 (+1.4/-1.5) kcal/mol.

Photodissociation of nitromethane cluster anions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Goebbert, Daniel J.; Khuseynov, Dmitry; Sanov, Andrei

2010-08-28

Three types of anionic fragments are observed in the photodissociation of nitromethane cluster anions, (CH{sub 3}NO{sub 2}){sub n}{sup -}, n=1-6, at 355 nm: NO{sub 2}{sup -}(CH{sub 3}NO{sub 2}){sub k}, (CH{sub 3}NO{sub 2}){sub k}{sup -}, and OH{sup -} (kphotodissociation of CH{sub 3}NO{sub 2}{sup -} requires lower energy photons because the photochemically active electron occupies a high energy {pi}{sup *} orbital (which is vacant in the neutral). Although the electronic states in the photodissociation of CH{sub 3}NO{sub 2} and CH{sub 3}NO{sub 2}{sup -} are different, the major fragments, CH{sub 3}+NO{sub 2} and CH{sub 3}+NO{sub 2}{sup -}, respectively, both form via C-N bond cleavage.« less

Planar measurement of flow field parameters in a nonreacting supersonic combustor using laser-induced iodine fluorescence

NASA Technical Reports Server (NTRS)

Hartfield, Roy J., Jr.; Hollo, Steven D.; Mcdaniel, James C.

1990-01-01

A nonintrusive optical technique, laser-induced iodine fluorescence, has been used to obtain planar measurements of flow field parameters in the supersonic mixing flow field of a nonreacting supersonic combustor. The combustor design used in this work was configured with staged transverse sonic injection behind a rearward-facing step into a Mach 2.07 free stream. A set of spatially resolved measurements of temperature and injectant mole fraction has been generated. These measurements provide an extensive and accurate experimental data set required for the validation of computational fluid dynamic codes developed for the calculation of highly three-dimensional combustor flow fields.

Vacuum Ultraviolet Photodissociation and Fourier Transform-Ion Cyclotron Resonance (FT-ICR) Mass Spectrometry: Revisited.

PubMed

Shaw, Jared B; Robinson, Errol W; Paša-Tolić, Ljiljana

2016-03-15

We revisited the implementation of 193 nm ultraviolet photodissociation (UVPD) within the ion cyclotron resonance (ICR) cell of a Fourier transform-ion cyclotron resonance (FT-ICR) mass spectrometer. UVPD performance characteristics were examined in the context of recent developments in the understanding of UVPD and in-cell tandem mass spectrometry. Efficient UVPD and photo-ECD of a model peptide and proteins within the ICR cell of a FT-ICR mass spectrometer are accomplished through appropriate modulation of laser pulse timing, relative to ion magnetron motion and the potential applied to an ion optical element upon which photons impinge. It is shown that UVPD yields efficient and extensive fragmentation, resulting in excellent sequence coverage for model peptide and protein cations.

Bibliography of Soviet Laser Developments, Number 26, October - December 1976.

DTIC Science & Technology

1977-07-25

Arevyan, N.N. Petrov, and L.V. Sukhanov (0). Photodissociative short-pulse laser with gain modulation of the medium by a magnetic field. KE, no. 11...L________________________________________________ 120. Sukhanov , I.I. and Yu.V. Troitskiy (75). Mode-locking control in a gas laser by a phase interferometer. KE, no. 12, 1976 a 2596-2605. 121

Advantage of spatial map ion imaging in the study of large molecule photodissociation

NASA Astrophysics Data System (ADS)

Lee, Chin; Lin, Yen-Cheng; Lee, Shih-Huang; Lee, Yin-Yu; Tseng, Chien-Ming; Lee, Yuan-Tseh; Ni, Chi-Kung

2017-07-01

The original ion imaging technique has low velocity resolution, and currently, photodissociation is mostly investigated using velocity map ion imaging. However, separating signals from the background (resulting from undissociated excited parent molecules) is difficult when velocity map ion imaging is used for the photodissociation of large molecules (number of atoms ≥ 10). In this study, we used the photodissociation of phenol at the S1 band origin as an example to demonstrate how our multimass ion imaging technique, based on modified spatial map ion imaging, can overcome this difficulty. The photofragment translational energy distribution obtained when multimass ion imaging was used differed considerably from that obtained when velocity map ion imaging and Rydberg atom tagging were used. We used conventional translational spectroscopy as a second method to further confirm the experimental results, and we conclude that data should be interpreted carefully when velocity map ion imaging or Rydberg atom tagging is used in the photodissociation of large molecules. Finally, we propose a modified velocity map ion imaging technique without the disadvantages of the current velocity map ion imaging technique.

Iodine Deficiency and Iodine Prophylaxis in Pregnancy.

PubMed

Trofimiuk-Mudlner, Malgorzata; Hubalewska-Dydejczyk, Alicja

2017-01-01

Physiological changes in pregnancy result in increased iodine demand, which may not be met in areas of mild-to-moderate iodine deficiency or borderline sufficiency. As a pregnant woman is the only source of thyroid hormones for her child during early gestation, iodine deficiencyinduced hypothyroxinemia may have deleterious effects on fetal development. To present the current approach to iodine deficiency and its prophylaxis during pregnancy. A review of the current literature including patents on iodine deficiency in pregnancy has been performed. Negative influence of severe iodine deficiency on fetal development has been proved, and evidence on a deleterious impact of milder forms of iodine deficiency on cognition of the offspring is rapidly growing. Although the WHO has addressed the issues of monitoring iodine status during pregnancy, prophylactic measures and assessment of their effectiveness, there are some controversies, regarding for example the best methods for control of iodine status. New patents in urinary iodine measurement methods may make iodine nutrition monitoring easier. The main method of iodine prophylaxis, in pregnancy also, is universal salt iodization. However, particularly if there is not sufficient coverage of the households with iodized salt, additional measures, such as oral supplementation with potassium iodide tablets, are necessary in pregnant women to provide adequate iodine nutrition. Iodine supplementation improves maternal thyroid function indices; particularly, it prevents goiter formation. Stronger evidence on beneficial effects of iodine supplementation of mild-to-moderate iodine deficient pregnant women on cognitive function of their children is still needed. It may be provided by randomized controlled trials and international initiatives. Changes in the iodine prophylaxis system should be monitored, both to prevent decreased or excessive iodine intake. Copyright© Bentham Science Publishers; For any queries, please email at

LASER APPLICATIONS AND OTHER TOPICS IN QUANTUM ELECTRONICS: The 2P1/2 → 2P3/2 laser transition in atomic iodine and the problem of search for signals from extraterrestrial intelligence

NASA Astrophysics Data System (ADS)

Kutaev, Yu F.; Mankevich, S. K.; Nosach, O. Yu; Orlov, E. P.

2007-07-01

It is proposed to search for signals from extraterrestrial intelligence (ETI) at a wavelength of 1.315 μm of the laser 2P1/2 → 2P3/2 transition in the atomic iodine, which can be used for this purpose as the natural frequency reference. The search at this wavelength is promising because active quantum filters (AQFs) with the quantum sensitivity limit have been developed for this wavelength, which are capable of receiving laser signals, consisting of only a few photons, against the background of emission from a star under study. In addition, high-power iodine lasers emitting diffraction-limited radiation at 1.315 μm have been created, which highly developed ETI also can have. If a ETI sends in our direction a diffraction-limited 10-ns, 1-kJ laser pulse with the beam diameter of 10 m, a receiver with an AQF mounted on a ten-meter extra-atmospheric optical telescope can detect this signal at a distance of up to 300 light years, irrespective of the ETI position on the celestial sphere. The realisation of the projects for manufacturing optical telescopes of diameter 30 m will increase the research range up to 2700 light years. A weak absorption of the 1.315-μm radiation in the Earth atmosphere (the signal is attenuated by less than 20%) allows the search for ETI signals by using ground telescopes equipped with adaptive optical systems.

Charge-transfer photodissociation of adsorbed molecules via electron image states

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jensen, E. T.

The 248 and 193 nm photodissociations of submonolayer quantities of CH{sub 3}Br and CH{sub 3}I adsorbed on thin layers of n-hexane indicate that the dissociation is caused by dissociative electron attachment from subvacuum level photoelectrons created in the copper substrate. The characteristics of this photodissociation-translation energy distributions and coverage dependences show that the dissociation is mediated by an image potential state which temporarily traps the photoelectrons near the n-hexane-vacuum interface, and then the charge transfers from this image state to the affinity level of a coadsorbed halomethane which then dissociates.

Electronic excitation energies, three-state intersections, and photodissociation mechanisms of benzaldehyde and acetophenone

NASA Astrophysics Data System (ADS)

Cui, Ganglong; Lu, You; Thiel, Walter

2012-06-01

We report a theoretical study on the electronically excited states and the mechanisms of photodissociation of C6H5CHO and C6H5COCH3. For both molecules, we find an S1/T2/T1 three-state intersection region, which allows for an efficient S1 → T1 intersystem crossing via the T2 state that acts as a relay. Consequently, T1 reactions become the major radical photodissociation channels. According to the computed energy profiles, T1 photodissociation mainly yields phenyl and formyl radicals in the case of benzaldehyde, and benzoyl and methyl radicals in the case of acetophenone, with different C-C bonds being cleaved preferentially. The computational results agree well with the available experimental data.

Iodine

MedlinePlus

... the uterus (endometritis). Washing the vagina with a solution containing iodine in the form of povidone-iodine ... infection (periodontitis). Research suggests that rinsing with a solution containing iodine in the form of povidone-iodine ...

Photodissociation of ultracold diatomic strontium molecules with quantum state control.

PubMed

McDonald, M; McGuyer, B H; Apfelbeck, F; Lee, C-H; Majewska, I; Moszynski, R; Zelevinsky, T

2016-07-07

Chemical reactions at ultracold temperatures are expected to be dominated by quantum mechanical effects. Although progress towards ultracold chemistry has been made through atomic photoassociation, Feshbach resonances and bimolecular collisions, these approaches have been limited by imperfect quantum state selectivity. In particular, attaining complete control of the ground or excited continuum quantum states has remained a challenge. Here we achieve this control using photodissociation, an approach that encodes a wealth of information in the angular distribution of outgoing fragments. By photodissociating ultracold (88)Sr2 molecules with full control of the low-energy continuum, we access the quantum regime of ultracold chemistry, observing resonant and nonresonant barrier tunnelling, matter-wave interference of reaction products and forbidden reaction pathways. Our results illustrate the failure of the traditional quasiclassical model of photodissociation and instead are accurately described by a quantum mechanical model. The experimental ability to produce well-defined quantum continuum states at low energies will enable high-precision studies of long-range molecular potentials for which accurate quantum chemistry models are unavailable, and may serve as a source of entangled states and coherent matter waves for a wide range of experiments in quantum optics.

THE PHOTODISSOCIATION OF FORMALDEHYDE IN COMETS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Feldman, Paul D., E-mail: pfeldman@jhu.edu

2015-10-20

Observations of comets in the 905–1180 Å spectral band made with the Far Ultraviolet Spectroscopic Explorer in 2001 and 2004 show unusual features in the fluorescent emissions of CO and H{sub 2}. These include emission from a non-thermal high-J rotational population of CO and solar Lyα induced fluorescence from excited vibrational levels of H{sub 2}, both of which are attributed to the photodissociation of formaldehyde. In this paper we model the large number of observed H{sub 2} lines and demonstrate the dependence of the pumping on the heliocentric velocity of the comet and the solar line profiles. We also derivemore » the rotational and vibrational populations of H{sub 2} and show that they are consistent with the results of laboratory studies of the photodissociation of H{sub 2}CO. In addition to the principal series of H i and O i, the residual spectrum is found to consist mainly of the Rydberg series of C i multiplets from which we derive the mean carbon column abundance in the coma. Fluorescent emissions from N i and N{sub 2} are also searched for.« less

Advanced solar energy conversion. [solar pumped gas lasers

NASA Technical Reports Server (NTRS)

Lee, J. H.

1981-01-01

An atomic iodine laser, a candidate for the direct solar pumped lasers, was successfully excited with a 4 kW beam from a xenon arc solar simulator, thus proving the feasibility of the concept. The experimental set up and the laser output as functions of operating conditions are presented. The preliminary results of the iodine laser amplifier pumped with the HCP array to which a Q switch for giant pulse production was coupled are included. Two invention disclosures - a laser driven magnetohydrodynamic generator for conversion of laser energy to electricity and solar pumped gas lasers - are also included.

The photodissociation and chemistry of CO isotopologues: applications to interstellar clouds and circumstellar disks

NASA Astrophysics Data System (ADS)

Visser, R.; van Dishoeck, E. F.; Black, J. H.

2009-08-01

Aims: Photodissociation by UV light is an important destruction mechanism for carbon monoxide (CO) in many astrophysical environments, ranging from interstellar clouds to protoplanetary disks. The aim of this work is to gain a better understanding of the depth dependence and isotope-selective nature of this process. Methods: We present a photodissociation model based on recent spectroscopic data from the literature, which allows us to compute depth-dependent and isotope-selective photodissociation rates at higher accuracy than in previous work. The model includes self-shielding, mutual shielding and shielding by atomic and molecular hydrogen, and it is the first such model to include the rare isotopologues C17O and 13C17O. We couple it to a simple chemical network to analyse CO abundances in diffuse and translucent clouds, photon-dominated regions, and circumstellar disks. Results: The photodissociation rate in the unattenuated interstellar radiation field is 2.6 × 10-10 s-1, 30% higher than currently adopted values. Increasing the excitation temperature or the Doppler width can reduce the photodissociation rates and the isotopic selectivity by as much as a factor of three for temperatures above 100 K. The model reproduces column densities observed towards diffuse clouds and PDRs, and it offers an explanation for both the enhanced and the reduced N(12CO)/N(13CO) ratios seen in diffuse clouds. The photodissociation of C17O and 13C17O shows almost exactly the same depth dependence as that of C18O and 13C18O, respectively, so 17O and 18O are equally fractionated with respect to 16O. This supports the recent hypothesis that CO photodissociation in the solar nebula is responsible for the anomalous 17O and 18O abundances in meteorites. Grain growth in circumstellar disks can enhance the N(12CO)/N(C17O) and N(12CO)/N(C18O) ratios by a factor of ten relative to the initial isotopic abundances. Tables [see full textsee full text]-[see full textsee full text] are only

Exploding conducting film laser pumping apparatus

DOEpatents

Ware, Kenneth D.; Jones, Claude R.

1986-01-01

Exploding conducting film laser optical pumping apparatus. The 342-nm molecular iodine and the 1.315-.mu.m atomic iodine lasers have been optically pumped by intense light from exploding-metal-film discharges. Brightness temperatures for the exploding-film discharges were approximately 25,000 K. Although lower output energies were achieved for such discharges when compared to exploding-wire techniques, the larger surface area and smaller inductance inherent in the exploding-film should lead to improved efficiency for optically-pumped gas lasers.

Photodissociation of CO2 and quenching of metastables

NASA Technical Reports Server (NTRS)

Slanger, T. G.

1978-01-01

Investigations in four different areas were carried out to further our understanding of the chemistry of the atmospheres of Mars and Venus. CO2 photodissociation quantum yields were determined in the 1300-1500 A spectral region by measuring both CO and oxygen atoms. The O(1S) quantum yield was determined for CO2 photodissociation in the 1060-1175 A spectral region. The measurement resolves the differences between two earlier experiments, and demonstrates that the O(1S) yield is unity throughout most of the measured region. The pathways for the quenching of O(1S) by N2O, CO2, H2O and NO were investigated and the source of the Venus nightglow, detected by Venera 9 and 10, was investigated. What appears to be a new O2 band system, was detected although the identity of the transition is not yet evident.

Isotope separation by selective photodissociation of glyoxal

DOEpatents

Marling, John B.

1976-01-01

Dissociation products, mainly formaldehyde and carbon monoxide, enriched in a desired isotope of carbon, oxygen, or hydrogen are obtained by the selective photodissociation of glyoxal wherein glyoxal is subjected to electromagnetic radiation of a predetermined wavelength such that photon absorption excites and induces dissociation of only those molecules of glyoxal containing the desired isotope.

Direct solar-pumped iodine laser amplifier

NASA Technical Reports Server (NTRS)

Han, Kwang S.; Kim, K. H.; Stock, L. V.

1986-01-01

In order to evaluate the feasibility of the solar pumped dye laser, the parametric study of a dye laser amplifier pumped by a solar simulator and flashlamp was carried out, and the amplifier gains were measured at various pump beam irradiances on the dye cell. Rhodamine 6G was considered as a candidate for the solar pumped laser because of its good utilization of the solar spectrum and high quantum efficiency. The measurement shows that a solar concentration of 20,000 is required to reach the threshold of the dye. The work to construct a kinetic model algorithm which predicts the output parameter of laser was progressed. The kinetic model was improved such that there is good agreement between the theoretical model and experimental data for the systems defined previously as flashlamp pumped laser oscillator, and the long path length solar pumped laser.

Studies of new media radiation induced laser

NASA Technical Reports Server (NTRS)

Han, K. S.; Shiu, Y. J.; Raju, S. R.; Hwang, I. H.; Tabibi, B.

1984-01-01

Various lasants were investigated especially, 2-iodohepafluoropropane (i-C3F7I) for the direct solar pumped lasers. Optical pumping of iodine laser was achieved using a small flashlamp. Using i-C3F7I as a laser gain medium, threshold inversion density, small signal gain, and laser performance at the elevated temperature were measured. The experimental results and analysis are presented. The iodine laser kinetics of the C3F7I and IBr system were numerically simulated. The concept of a direct solar-pumped laser amplifier using (i-C3F7I) as the laser material was evaluated and several kinetic coefficients for i-C3F7I laser system were reexamined. The results are discussed.

The Photodissociation of HCN and HNC: Effects on the HNC/HCN Abundance Ratio in the Interstellar Medium

NASA Astrophysics Data System (ADS)

Aguado, Alfredo; Roncero, Octavio; Zanchet, Alexandre; Agúndez, Marcelino; Cernicharo, José

2017-03-01

The impact of the photodissociation of HCN and HNC isomers is analyzed in different astrophysical environments. For this purpose, the individual photodissociation cross sections of HCN and HNC isomers have been calculated in the 7-13.6 eV photon energy range for a temperature of 10 K. These calculations are based on the ab initio calculation of three-dimensional adiabatic potential energy surfaces of the 21 lower electronic states. The cross sections are then obtained using a quantum wave packet calculation of the rotational transitions needed to simulate a rotational temperature of 10 K. The cross section calculated for HCN shows significant differences with respect to the experimental one, and this is attributed to the need to consider non-adiabatic transitions. Ratios between the photodissociation rates of HCN and HNC under different ultraviolet radiation fields have been computed by renormalizing the rates to the experimental value. It is found that HNC is photodissociated faster than HCN by a factor of 2.2 for the local interstellar radiation field and 9.2 for the solar radiation field, at 1 au. We conclude that to properly describe the HNC/HCN abundance ratio in astronomical environments illuminated by an intense ultraviolet radiation field, it is necessary to use different photodissociation rates for each of the two isomers, which are obtained by integrating the product of the photodissociation cross sections and ultraviolet radiation field over the relevant wavelength range.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zagidullin, M V; Azyazov, V N; Malyshev, M S

The kinetics of the processes occurring in an O{sub 2} – I{sub 2} – He – H{sub 2}O gas flow in which photodissociation of molecular iodine at a wavelength close to 500 nm and excitation of atomic iodine on the {sup 2}P{sub 1/2} – {sup 2}P{sub 3/2} transition by narrow-band radiation near 1315 nm are implemented successively has been analysed. It is shown that implementation of these processes allows one to form an oxygen – iodine medium with a high degree of dissociation of molecular iodine and a relative content of singlet oxygen O{sub 2}(a{sup 1}Δ) exceeding 10%. Having formedmore » a supersonic gas flow with a temperature ∼100 K from this medium, one can reach a small-signal gain of about 10{sup -2} cm{sup -1} on the {sup 2}P{sub 1/2} – {sup 2}P{sub 3/2} transition in iodine atoms. The specific power per unit flow cross section in the oxygen – iodine laser with this active medium may reach ∼100 W cm{sup -2}. (active media)« less

Ultrastable laser array at 633 nm for real-time dimensional metrology

NASA Astrophysics Data System (ADS)

Lawall, John; Pedulla, J. Marc; Le Coq, Yann

2001-07-01

We describe a laser system for very-high-accuracy dimensional metrology. A sealed-cavity helium-neon laser is offset locked to an iodine-stabilized laser in order to realize a secondary standard with higher power and less phase noise. Synchronous averaging is employed to remove the effect of the frequency modulation present on the iodine-stabilized laser. Additional lasers are offset locked to the secondary standard for use in interferometry. All servo loops are implemented digitally. The offset-locked lasers have intrinsic linewidths of the order of 2.5 kHz and exhibit a rms deviation from the iodine-stabilized laser below 18 kHz. The amplitude noise is at the shot-noise limit for frequencies above 700 kHz. We describe and evaluate the system in detail, and include a discussion of the noise associated with various types of power supplies.

Instantaneous imaging of ozone in a gliding arc discharge using photofragmentation laser-induced fluorescence

NASA Astrophysics Data System (ADS)

Larsson, Kajsa; Hot, Dina; Gao, Jinlong; Kong, Chengdong; Li, Zhongshan; Aldén, Marcus; Bood, Joakim; Ehn, Andreas

2018-04-01

Ozone vapor, O3, is here visualized in a gliding arc discharge using photofragmentation laser-induced fluorescence. Ozone is imaged by first photodissociating the O3 molecule into an O radical and a vibrationally hot O2 fragment by a pump photon. Thereafter, the vibrationally excited O2 molecule absorbs a second (probe) photon that further transits the O2-molecule to an excited electronic state, and hence, fluorescence from the deexcitation process in the molecule can be detected. Both the photodissociation and excitation processes are achieved within one 248 nm KrF excimer laser pulse that is formed into a laser sheet and the fluorescence is imaged using an intensified CCD camera. The laser-induced signal in the vicinity of the plasma column formed by the gliding arc is confirmed to stem from O3 rather than plasma produced vibrationally hot O2. While both these products can be produced in plasmas a second laser pulse at 266 nm was utilized to separate the pump- from the probe-processes. Such arrangement allowed lifetime studies of vibrationally hot O2, which under these conditions were several orders of magnitude shorter than the lifetime of plasma-produced ozone.

Iodine

USGS Publications Warehouse

Krukowski, S.T.

2006-01-01

In descending order, Chile, Japan and the United States have the largest iodine reserves. Chile produces iodine from iodate minerals while Japan and the United States produce it from sodium iodide solutions found in underground iodide solutions. Iodine is also produced from subterranean brines in Azerbaijan, Russia, Turkmenista, Indonesia and Uzbekistan. In 2005, iodine prices increased sharply to US$19 to US$23 then leveled off at US$23 to US$25.

LASER APPLICATIONS AND OTHER TOPICS IN QUANTUM ELECTRONICS: Study of photodissociation parameters of carboxyhemoglobin

NASA Astrophysics Data System (ADS)

Kuz'min, V. V.; Salmin, V. V.; Salmina, A. B.; Provorov, A. S.

2008-07-01

The general properties of photodissociation of carboxyhemoglobin (HbCO) in buffer solutions of whole human blood are studied by the flash photolysis method on a setup with intersecting beams. It is shown that the efficiency of photoinduced dissociation of the HbCO complex virtually linearly depends on the photolytic irradiation intensity for the average power density not exceeding 45 mW cm-2. The general dissociation of the HbCO complex in native conditions occurs in a narrower range of values of the saturation degree than in model experiments with the hemoglobin solution. The dependence of the pulse photolysis efficiency of HbCO on the photolytic radiation wavelength in the range from 550 to 585 nm has a broad bell shape. The efficiency maximum corresponds to the electronic Q transition (porphyrin π—π* absorption) in HbCO at a wavelength of 570 nm. No dissociation of the complex was observed under given experimental conditions upon irradiation of solutions by photolytic radiation at wavelengths above 585 nm.

Exploding conducting film laser pumping apparatus

DOEpatents

Ware, K.D.; Jones, C.R.

1984-04-27

The 342-nm molecular iodine and the 1.315-..mu..m atomic iodine lasers have been optically pumped by intense light from exploding-metal-film discharges. Brightness temperatures for the exploding-film discharges were approximately 25,000 K. Although lower output energies were achieved for such discharges when compared to exploding-wire techniques, the larger surface area and smaller inductance inherent in the exploding-film should lead to improved efficiency for optically-pumped gas lasers.

A new concept in laser-assisted chemistry - The electronic-field representation

NASA Technical Reports Server (NTRS)

George, T. F.; Zimmerman, I. H.; Yuan, J.-M.; Laing, J. R.; Devries, P. L.

1977-01-01

Electronic-field representation is proposed as a technique for laser-assisted chemistry. Specifically, it is shown that several field-assisted chemical processes can be described in terms of mixed matter-field quantum states and their associated energies. The technique may be used to analyze the effects exerted by an intense laser on both bound and unbound molecular systems, and to investigate other field-induced effects including multiphoton processes, emission, and photodissociation.

Highly Nuclear-Spin-Polarized Deuterium Atoms from the UV Photodissociation of Deuterium Iodide.

PubMed

Sofikitis, Dimitris; Glodic, Pavle; Koumarianou, Greta; Jiang, Hongyan; Bougas, Lykourgos; Samartzis, Peter C; Andreev, Alexander; Rakitzis, T Peter

2017-06-09

We report a novel highly spin-polarized deuterium (SPD) source, via the photodissociation of deuterium iodide at 270 nm. I(^{2}P_{3/2}) photofragments are ionized with m-state selectivity, and their velocity distribution measured via velocity-map slice imaging, from which the D polarization is determined. The process produces ∼100% electronically polarized D at the time of dissociation, which is then converted to ∼60% nuclear D polarization after ∼1.6  ns. These production times for SPD allow collision-limited densities of ∼10^{18}  cm^{-3} and at production rates of ∼10^{21}  s^{-1} which are 10^{6} and 10^{4} times higher than conventional (Stern-Gerlach separation) methods, respectively. We discuss the production of SPD beams, and combining high-density SPD with laser fusion, to investigate polarized D-T, D-^{3}He, and D-D fusion.

Anatomy of the Photodissociation Region in the Orion Bar

NASA Technical Reports Server (NTRS)

Tielens, A. G. G. M.; Meixner, M. M.; vanderWerf, P. P.; Bregman, J.; Tauber, J. A.; Stutzki, J.; Rank, D.

1993-01-01

Much of the interstellar gas resides in photodissociation regions whose chemistry and energy balance is controlled by the flux of far-ultraviolet radiation upon them. These photons can ionize and dissociate molecules and heat the gas through the photoelectric effect working on dust grains. These regions have been extensively modeled theoretically, but detailed observational studies are few. Mapping of the prominent Orion Bar photo-dissociation region at wavelengths corresponding to the carbon-hydrogen stretching mode of polycyclic aromatic hydrocarbons, the 1-0 S(l) line of molecular hydrogen, and the J = 1-0 rotational line of carbon monoxide allows the penetration of the far-ultraviolet radiation into the cloud to be traced. The results strongly support the theoretical models and show conclusively that the incident far-ultraviolet radiation field, not shocks as has sometimes been proposed, is responsible for the emission in the Orion Bar.

Photodissociation and photoionisation of atoms and molecules of astrophysical interest

NASA Astrophysics Data System (ADS)

Heays, A. N.; Bosman, A. D.; van Dishoeck, E. F.

2017-06-01

A new collection of photodissociation and photoionisation cross sections for 102 atoms and molecules of astrochemical interest has been assembled, along with a brief review of the basic physical processes involved. These have been used to calculate dissociation and ionisation rates, with uncertainties, in a standard ultraviolet interstellar radiation field (ISRF) and for other wavelength-dependent radiation fields, including cool stellar and solar radiation, Lyman-α dominated radiation, and a cosmic-ray induced ultraviolet flux. The new ISRF rates generally agree within 30% with our previous compilations, with a few notable exceptions. Comparison with other databases such as PHIDRATES is made. The reduction of rates in shielded regions was calculated as a function of dust, molecular and atomic hydrogen, atomic C, and self-shielding column densities. The relative importance of these shielding types depends on the atom or molecule in question and the assumed dust optical properties. All of the new data are publicly available from the Leiden photodissociation and ionisation database. Sensitivity of the calculated rates to variation of temperature and isotope, and uncertainties in measured or calculated cross sections, are tested and discussed. Tests were conducted on the new rates with an interstellar-cloud chemical model, and find general agreement (within a factor of two) in abundances obtained with the previous iteration of the Leiden database assuming an ISRF, and order-of-magnitude variations assuming various kinds of stellar radiation. The newly parameterised dust-shielding factors makes a factor-of-two difference to many atomic and molecular abundances relative to parameters currently in the UDfA and KIDA astrochemical reaction databases. The newly-calculated cosmic-ray induced photodissociation and ionisation rates differ from current standard values up to a factor of 5. Under high temperature and cosmic-ray-flux conditions the new rates alter the equilibrium

Solar-pumped laser for free space power transmission

NASA Technical Reports Server (NTRS)

Lee, Ja H.

1989-01-01

Laser power transmission; laser systems; space-borne and available lasers; 2-D and 1 MW laser diode array systems; technical issues; iodine solar pumped laser system; and laser power transmission applications are presented. This presentation is represented by viewgraphs only.

Atomic carbon emission from photodissociation of CO2. [planetary atmospheric chemistry

NASA Technical Reports Server (NTRS)

Wu, C. Y. R.; Phillips, E.; Lee, L. C.; Judge, D. L.

1978-01-01

Atomic carbon fluorescence, C I 1561, 1657, and 1931 A, has been observed from photodissociation of CO2, and the production cross sections have been measured. A line emission source provided the primary photons at wavelengths from threshold to 420 A. The present results suggest that the excited carbon atoms are produced by total dissociation of CO2 into three atoms. The cross sections for producing the O I 1304-A fluorescence through photodissociation of CO2 are found to be less than 0.01 Mb in the wavelength region from 420 to 835 A. The present data have implications with respect to photochemical processes in the atmospheres of Mars and Venus.

Photodissociation of pernitric acid (HO2NO2) at 248 nm

NASA Technical Reports Server (NTRS)

Macleod, Helene; Smith, Gregory P.; Golden, David M.

1989-01-01

The photodissociation of pernitric acid (PNA) was studied at 248 nm. The quantum yield for production of OH radicals is 34 + or - 16 percent. The yield of OH from PNA was measured relative to that of H2O2. The translational and rotational energy content of the OH photofragment from PNA was characterized. A fluorescent emission was also observed and characterized. It is attributed to electronically excited NO2 produced in the PNA photodissociation. A maximum yield of 30 percent for NO2 production was determined. The intensity of this emission, and a mass spectrometric peak at m/e = 33, were found to be useful means of characterizing the purity of the PNA sample.

Spectroscopy of Vibrational States in Diatomic Iodine Molecules

NASA Astrophysics Data System (ADS)

Mulholland, Mary; Harrill, Charles H.; Smith, R. Seth

2015-04-01

This project is focused on understanding the vibrational structure of iodine, which is a homonuclear diatomic molecule. A 20 mW, 532 nm cw diode laser was used to selectively excite neutral iodine molecules to a higher energy electronic state. By performing spectroscopy on the transitions from this state to a lower energy electronic state, the data only showed those vibrational bands which connect the two electronic states. Since a number of vibrational levels are populated in the higher energy electronic state, the transitions to all of the allowed vibrational levels in the lower energy electronic state provided sufficient data to determine the vibrational structures of both states. Emission spectra were collected with an Ocean Optics USB4000 Compact CCD Spectrometer. The spectrometer had a range of 500 - 770 nm with a resolution of approximately 0.5 nm and was sensitive enough to resolve the vibrational states in diatomic iodine molecules. The results were compared to a simple harmonic oscillator model.

Leveraging Electron Transfer Dissociation for Site Selective Radical Generation: Applications for Peptide Epimer Analysis

NASA Astrophysics Data System (ADS)

Lyon, Yana A.; Beran, Gregory; Julian, Ryan R.

2017-07-01

Traditional electron-transfer dissociation (ETD) experiments operate through a complex combination of hydrogen abundant and hydrogen deficient fragmentation pathways, yielding c and z ions, side-chain losses, and disulfide bond scission. Herein, a novel dissociation pathway is reported, yielding homolytic cleavage of carbon-iodine bonds via electronic excitation. This observation is very similar to photodissociation experiments where homolytic cleavage of carbon-iodine bonds has been utilized previously, but ETD activation can be performed without addition of a laser to the mass spectrometer. Both loss of iodine and loss of hydrogen iodide are observed, with the abundance of the latter product being greatly enhanced for some peptides after additional collisional activation. These observations suggest a novel ETD fragmentation pathway involving temporary storage of the electron in a charge-reduced arginine side chain. Subsequent collisional activation of the peptide radical produced by loss of HI yields spectra dominated by radical-directed dissociation, which can be usefully employed for identification of peptide isomers, including epimers.

UV photodissociation of proline-containing peptide ions: insights from molecular dynamics.

PubMed

Girod, Marion; Sanader, Zeljka; Vojkovic, Marin; Antoine, Rodolphe; MacAleese, Luke; Lemoine, Jérôme; Bonacic-Koutecky, Vlasta; Dugourd, Philippe

2015-03-01

UV photodissociation of proline-containing peptide ions leads to unusual product ions. In this paper, we report laser-induced dissociation of a series of proline-containing peptides at 213 nm. We observe specific fragmentation pathways corresponding to the formation of (y-2), (a + 2) and (b + 2) fragment ions. This was not observed at 266 nm or for peptides which do not contain proline residues. In order to obtain insights into the fragmentation dynamics at 213 nm, a small peptide (RPK for arginine-proline-lysine) was studied both theoretically and experimentally. Calculations of absorption spectra and non-adiabatic molecular dynamics (MD) were made. Second and third excited singlet states, S(2) and S(3), lie close to 213 nm. Non-adiabatic MD simulation starting from S(2) and S(3) shows that these transitions are followed by C-C and C-N bond activation close to the proline residue. After this first relaxation step, consecutive rearrangements and proton transfers are required to produce unusual (y-2), (a + 2) and (b + 2) fragment ions. These fragmentation mechanisms were confirmed by H/D exchange experiments.

UV Photodissociation of Proline-containing Peptide Ions: Insights from Molecular Dynamics

NASA Astrophysics Data System (ADS)

Girod, Marion; Sanader, Zeljka; Vojkovic, Marin; Antoine, Rodolphe; MacAleese, Luke; Lemoine, Jérôme; Bonacic-Koutecky, Vlasta; Dugourd, Philippe

2015-03-01

UV photodissociation of proline-containing peptide ions leads to unusual product ions. In this paper, we report laser-induced dissociation of a series of proline-containing peptides at 213 nm. We observe specific fragmentation pathways corresponding to the formation of (y-2), (a + 2) and (b + 2) fragment ions. This was not observed at 266 nm or for peptides which do not contain proline residues. In order to obtain insights into the fragmentation dynamics at 213 nm, a small peptide (RPK for arginine-proline-lysine) was studied both theoretically and experimentally. Calculations of absorption spectra and non-adiabatic molecular dynamics (MD) were made. Second and third excited singlet states, S2 and S3, lie close to 213 nm. Non-adiabatic MD simulation starting from S2 and S3 shows that these transitions are followed by C-C and C-N bond activation close to the proline residue. After this first relaxation step, consecutive rearrangements and proton transfers are required to produce unusual (y-2), (a + 2) and (b + 2) fragment ions. These fragmentation mechanisms were confirmed by H/D exchange experiments.

Microbial Transformation of Iodine: From Radioisotopes to Iodine Deficiency.

PubMed

Yeager, Chris M; Amachi, Seigo; Grandbois, Russell; Kaplan, Daniel I; Xu, Chen; Schwehr, Kathy A; Santschi, Peter H

2017-01-01

Iodine is a biophilic element that is important for human health, both as an essential component of several thyroid hormones and, on the other hand, as a potential carcinogen in the form of radioiodine generated by anthropogenic nuclear activity. Iodine exists in multiple oxidation states (-1, 0, +1, +3, +5, and +7), primarily as molecular iodine (I 2 ), iodide (I - ), iodate [Formula: see text] , or organic iodine (org-I). The mobility of iodine in the environment is dependent on its speciation and a series of redox, complexation, sorption, precipitation, and microbial reactions. Over the last 15years, there have been significant advances in iodine biogeochemistry, largely spurred by renewed interest in the fate of radioiodine in the environment. We review the biogeochemistry of iodine, with particular emphasis on the microbial processes responsible for volatilization, accumulation, oxidation, and reduction of iodine, as well as the exciting technological potential of these fascinating microorganisms and enzymes. Copyright © 2017 Elsevier Inc. All rights reserved.

Semiclassical Wigner theory of photodissociation in three dimensions: Shedding light on its basis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Arbelo-González, W.; CNRS, Institut des Sciences Moléculaires, UMR 5255, 33405 Talence; Université Bordeaux, Institut des Sciences Moléculaires, UMR 5255, 33405 Talence

2015-04-07

The semiclassical Wigner theory (SCWT) of photodissociation dynamics, initially proposed by Brown and Heller [J. Chem. Phys. 75, 186 (1981)] in order to describe state distributions in the products of direct collinear photodissociations, was recently extended to realistic three-dimensional triatomic processes of the same type [Arbelo-González et al., Phys. Chem. Chem. Phys. 15, 9994 (2013)]. The resulting approach, which takes into account rotational motions in addition to vibrational and translational ones, was applied to a triatomic-like model of methyl iodide photodissociation and its predictions were found to be in nearly quantitative agreement with rigorous quantum results, but at a muchmore » lower computational cost, making thereby SCWT a potential tool for the study of polyatomic reaction dynamics. Here, we analyse the main reasons for this agreement by means of an elementary model of fragmentation explicitly dealing with the rotational motion only. We show that our formulation of SCWT makes it a semiclassical approximation to an approximate planar quantum treatment of the dynamics, both of sufficient quality for the whole treatment to be satisfying.« less

Photodissociation of quantum state-selected diatomic molecules yields new insight into ultracold chemistry

NASA Astrophysics Data System (ADS)

McDonald, Mickey; McGuyer, Bart H.; Lee, Chih-Hsi; Apfelbeck, Florian; Zelevinsky, Tanya

2016-05-01

When a molecule is subjected to a sufficiently energetic photon it can break apart into fragments through a process called ``photodissociation''. For over 70 years this simple chemical reaction has served as a vital experimental tool for acquiring information about molecular structure, since the character of the photodissociative transition can be inferred by measuring the 3D photofragment angular distribution (PAD). While theoretical understanding of this process has gradually evolved from classical considerations to a fully quantum approach, experiments to date have not yet revealed the full quantum nature of this process. In my talk I will describe recent experiments involving the photodissociation of ultracold, optical lattice-trapped, and fully quantum state-resolved 88Sr2 molecules. Optical absorption images of the PADs produced in these experiments reveal features which are inherently quantum mechanical in nature, such as matter-wave interference between output channels, and are sensitive to the quantum statistics of the molecular wavefunctions. The results of these experiments cannot be predicted using quasiclassical methods. Instead, we describe our results with a fully quantum mechanical model yielding new intuition about ultracold chemistry.

Quantitative measurement of transverse injector and free stream interaction in a nonreacting SCRAMJET combustor using laser-induced iodine fluorescence

NASA Technical Reports Server (NTRS)

Fletcher, D. G.; Mcdaniel, J. C.

1987-01-01

A preliminary quantitative study of the compressible flowfield in a steady, nonreacting model SCRAMJET combustor using laser-induced iodine fluorescence (LIIF) is reported. Measurements of density, temperature, and velocity were conducted with the calibrated, nonintrusive, optical technique for two different combustor operating conditions. First, measurements were made in the supersonic flow over a rearward-facing step without transverse injection for comparison with calculated pressure profiles. The second configuration was staged injection behind the rearward-facing step at an injection dynamic pressure ratio of 1.06. These experimental results will be used to validate computational fluid dynamic (CFD) codes being developed to model supersonic combustor flowfields.

Laser Doppler velocimetry for continuous flow solar-pumped iodine laser system

NASA Technical Reports Server (NTRS)

Tabibi, Bagher M.; Lee, Ja H.

1991-01-01

A laser Doppler velocimetry (LDV) system was employed to measure the flow velocity profile of iodide vapor inside laser tubes of 36 mm ID and 20 mm ID. The LDV, which was operated in the forward scatter mode used a low power (15 mW) He-Ne laser beam. Velocity ranges from 1 m/s was measured to within one percent accuracy. The flow velocity profile across the laser tube was measured and the intensity of turbulence was determined. The flow of iodide inside the laser tube demonstrated a mixture of both turbulence and laminar flow. The flowmeter used for the laser system previously was calibrated with the LDV and found to be in good agreement.

Evaluation of iodine nutritional status in Tehran, Iran: iodine deficiency within iodine sufficiency.

PubMed

Nazeri, Pantea; Mirmiran, Parvin; Mehrabi, Yadollah; Hedayati, Mehdi; Delshad, Hossein; Azizi, Fereidoun

2010-12-01

Production of iodized salt in Iran for household consumption began in 1990. Previous studies have reported sustainable elimination of iodine deficiency disorders in Iran. The aim of this study was to evaluate the iodine nutritional status in Tehran in 2009. In this cross-sectional study, 383 Tehranian households were enrolled through randomized cluster sampling and a total of 639 adult subjects (242 men and 397 women), aged 19 and over, participated. A 24-hour urine sample was collected for measurement of urinary iodine, sodium, and creatinine concentrations using the digestion method, flame photometry, and autoanalyzer assay, respectively. Salt intake was estimated and iodine content of household salt was measured by titration. Median (interquartile range) iodine content of household salt and urinary iodine concentration (UIC) in Tehran were 21.2 (3.2-31.7) parts per million and 70.0 (34.0-131.2) μg/L, respectively. There was no statistically significant difference in 24-hour UICs between men and women. Median (interquartile range) daily salt intake was 7.6 (5.5-9.8) g, which was not different in the two genders. According to the WHO/ICCIDD/UNICEF classification, 11.2%, 25.9%, 26.7%, 25.1%, 8.0%, and 3.2% of participants had UIC <20, 20-49, 50-99, 100-199, 200-299, and >300 μg/L, respectively. Mild iodine deficiency has recurred in Tehranians. The results emphasize the need for continuous monitoring in all regions, even in a country with iodine sufficiency.

Control of photodissociation and photoionization of the NaI molecule by dynamic Stark effect.

PubMed

Han, Yong-Chang; Yuan, Kai-Jun; Hu, Wen-Hui; Cong, Shu-Lin

2009-01-28

The diabatic photodissociation and photoionization processes of the NaI molecule are studied theoretically using the quantum wave packet method. A pump laser pulse is used to prepare a dissociation wave packet that propagates through both the ionic channel (NaI-->Na(+)+I(-)) and the covalent channel (NaI-->Na+I). A Stark pulse is used to control the diabatic dissociation dynamics and a probe pulse is employed to ionize the products from the two channels. Based on the first order nonresonant nonperturbative dynamic Stark effect, the dissociation probabilities and the branching ratio of the products from the two channels can be controlled. Moreover the final photoelectron kinetic energy distribution can also be affected by the Stark pulse. The influences of the delay time, intensity, frequency, and carrier-envelope phase of the Stark pulse on the dissociation and ionization dynamics of the NaI molecule are discussed in detail.

The {sup 2}P{sub 1/2} {yields} {sup 2}P{sub 3/2} laser transition in atomic iodine and the problem of search for signals from extraterrestrial intelligence

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kutaev, Yu F; Mankevich, S K; Nosach, O Yu

2007-07-31

It is proposed to search for signals from extraterrestrial intelligence (ETI) at a wavelength of 1.315 {mu}m of the laser {sup 2}P{sub 1/2} {yields} {sup 2}P{sub 3/2} transition in the atomic iodine, which can be used for this purpose as the natural frequency reference. The search at this wavelength is promising because active quantum filters (AQFs) with the quantum sensitivity limit have been developed for this wavelength, which are capable of receiving laser signals, consisting of only a few photons, against the background of emission from a star under study. In addition, high-power iodine lasers emitting diffraction-limited radiation at 1.315more » {mu}m have been created, which highly developed ETI also can have. If a ETI sends in our direction a diffraction-limited 10-ns, 1-kJ laser pulse with the beam diameter of 10 m, a receiver with an AQF mounted on a ten-meter extra-atmospheric optical telescope can detect this signal at a distance of up to 300 light years, irrespective of the ETI position on the celestial sphere. The realisation of the projects for manufacturing optical telescopes of diameter 30 m will increase the research range up to 2700 light years. A weak absorption of the 1.315-{mu}m radiation in the Earth atmosphere (the signal is attenuated by less than 20%) allows the search for ETI signals by using ground telescopes equipped with adaptive optical systems. (laser applications and other topics in quantum electronics)« less

Proposed Molecular Beam Determination of Energy Partition in the Photodissociation of Polyatomic Molecules

DOE R&D Accomplishments Database

Zare, P. N.; Herschbach, D. R.

1964-01-29

Conventional photochemical experiments give no information about the partitioning of energy between translational recoil and internal excitation of the fragment molecules formed in photodissociation of a polyatomic molecule. In a molecular beam experiment, it becomes possible to determine the energy partition from the form of the laboratory angular distribution of one of the photodissociation products. A general kinematic analysis is worked out in detail, and the uncertainty introduced by the finite angular resolution of the apparatus and the velocity spread in the parent beam is examined. The experimental requirements are evaluated for he photolysis of methyl iodide by the 2537 angstrom Hg line.

Photodissociation spectroscopy of the dysprosium monochloride molecular ion

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dunning, Alexander, E-mail: alexander.dunning@gmail.com; Schowalter, Steven J.; Puri, Prateek

2015-09-28

We have performed a combined experimental and theoretical study of the photodissociation cross section of the molecular ion DyCl{sup +}. The photodissociation cross section for the photon energy range 35 500 cm{sup −1} to 47 500 cm{sup −1} is measured using an integrated ion trap and time-of-flight mass spectrometer; we observe a broad, asymmetric profile that is peaked near 43 000 cm{sup −1}. The theoretical cross section is determined from electronic potentials and transition dipole moments calculated using the relativistic configuration-interaction valence-bond and coupled-cluster methods. The electronic structure of DyCl{sup +} is extremely complex due to the presence of multiple open electronic shells,more » including the 4f{sup 10} configuration. The molecule has nine attractive potentials with ionically bonded electrons and 99 repulsive potentials dissociating to a ground state Dy{sup +} ion and Cl atom. We explain the lack of symmetry in the cross section as due to multiple contributions from one-electron-dominated transitions between the vibrational ground state and several resolved repulsive excited states.« less

Urinary iodine concentration identifies pregnant women as iodine deficient yet school-aged children as iodine sufficient in rural Niger.

PubMed

Hess, Sonja Y; Ouédraogo, Césaire T; Young, Rebecca R; Bamba, Ibrahim F; Stinca, Sara; Zimmermann, Michael B; Wessells, K Ryan

2017-05-01

To assess iodine status among pregnant women in rural Zinder, Niger and to compare their status with the iodine status of school-aged children from the same households. Seventy-three villages in the catchment area of sixteen health centres were randomly selected to participate in the cross-sectional survey. Salt iodization is mandatory in Niger, requiring 20-60 ppm iodine at the retail level. A spot urine sample was collected from randomly selected pregnant women (n 662) and one school-aged child from the same household (n 373). Urinary iodine concentration (UIC) was assessed as an indicator of iodine status in both groups. Dried blood spots (DBS) were collected from venous blood samples of pregnant women and thyroglobulin (Tg), thyroid-stimulating hormone and total thyroxine were measured. Iodine content of household salt samples (n 108) was assessed by titration. Median iodine content of salt samples was 5·5 ppm (range 0-41 ppm), 98 % had an iodine content 40 µg/l. In this region of Niger, most salt is inadequately iodized. UIC in pregnant women indicated iodine deficiency, whereas UIC of school-aged children indicated marginally adequate iodine status. Thus, estimating population iodine status based solely on monitoring of UIC among school-aged children may underestimate the risk of iodine deficiency in pregnant women.

Comparison of the Detection Characteristics of Trace Species Using Laser-Induced Breakdown Spectroscopy and Laser Breakdown Time-of-Flight Mass Spectrometry

PubMed Central

Wang, Zhenzhen; Deguchi, Yoshihiro; Yan, Junjie; Liu, Jiping

2015-01-01

The rapid and precise element measurement of trace species, such as mercury, iodine, strontium, cesium, etc. is imperative for various applications, especially for industrial needs. The elements mercury and iodine were measured by two detection methods for comparison of the corresponding detection features. A laser beam was focused to induce plasma. Emission and ion signals were detected using laser-induced breakdown spectroscopy (LIBS) and laser breakdown time-of-flight mass spectrometry (LB-TOFMS). Multi-photon ionization and electron impact ionization in the plasma generation process can be controlled by the pressure and pulse width. The effect of electron impact ionization on continuum emission, coexisting molecular and atomic emissions became weakened in low pressure condition. When the pressure was less than 1 Pa, the plasma was induced by laser dissociation and multi-photon ionization in LB-TOFMS. According to the experimental results, the detection limits of mercury and iodine in N2 were 3.5 ppb and 60 ppb using low pressure LIBS. The mercury and iodine detection limits using LB-TOFMS were 1.2 ppb and 9.0 ppb, which were enhanced due to different detection features. The detection systems of LIBS and LB-TOFMS can be selected depending on the condition of each application. PMID:25769051

The Photodissociation of Nitromethane at 193 nm.

DTIC Science & Technology

1983-02-28

available energy for product translational + internal energy is 90 kcal/mole. As the largest amount of energy that goes into translational energy in the...CATAL.O8 NUMIER 0 R 92-545/21W83 P 3-/ 4. TITLE (and Subtlee) S. TYPE OF REPORT A PEI4o0 COVERED THE PHOTODISSOCIATION OF NITROMETHANE AT 193 NM Technical S...been investigated by two independent and comple- *_ mentary techniques, product emission spectroscopy and molecular beam photofragment translational

Spectral properties of molecular iodine in absorption cells filled to specified saturation pressure.

PubMed

Hrabina, Jan; Šarbort, Martin; Acef, Ouali; Burck, Frédéric Du; Chiodo, Nicola; Holá, Miroslava; Číp, Ondřej; Lazar, Josef

2014-11-01

We present the results of measurement and evaluation of spectral properties of iodine absorption cells filled at certain saturation pressure. A set of cells made of borosilicate glass instead of common fused silica was tested for their spectral properties in greater detail with special care for the long-term development of the absorption media purity. The results were compared with standard fused silica cells and the high quality of iodine was verified. A measurement method based on an approach relying on measurement of linewidth of the hyperfine transitions is proposed as a novel technique for iodine cell absorption media purity evaluation. A potential application in laser metrology of length is also discussed.

Iodine status in pregnancy and household salt iodine content in rural Bangladesh.

PubMed

Shamim, Abu Ahmed; Christian, Parul; Schulze, Kerry J; Ali, Hasmot; Kabir, Alamgir; Rashid, Mahbubur; Labrique, Alain; Salamatullah, Qauzi; West, Keith P

2012-04-01

Adequate maternal iodine intake is essential during pregnancy for the development of the foetus. To assess the extent of iodine insufficiency and its association with household iodized salt in rural Bangladesh, we measured urinary iodine and household salt iodine content among pregnant women in early (≤16 weeks, n = 1376) and late (≥32 weeks, n = 1114) pregnancy. Salt (∼20 g) and a spot urine sample (∼10 mL) were collected from women participating in a randomized, placebo-controlled trial of vitamin A or beta-carotene supplementation in rural northwestern Bangladesh during home visits in early and late pregnancy. Salt iodine was analyzed by iodometric titration, and urinary iodine by the Ohashi method. Almost all salt samples had some detectable iodine, but over 75% contained <15 ppm. Median (interquartile range) urinary iodine concentrations were 66 (34-133) and 55 (28-110) µg L⁻¹ in early and late pregnancy, respectively; urinary iodine <150 µg L⁻¹ was found in ∼80% of women at both times in pregnancy. Although the risk of iodine insufficiency declined with increasing iodine content of household salt (P for trend <0.05), median urinary iodine did not reach 150 µg L⁻¹ until iodine in household salt was at least 32 ppm and 51 ppm during early and late pregnancy, respectively. Despite a national policy on universal salt iodization, salt iodine content remains insufficient to maintain adequate maternal iodine status throughout pregnancy in rural northern Bangladesh. Alternative measures like direct iodine supplementation during pregnancy could be considered to assure adequate iodine status during this high-risk period of life. © 2010 Blackwell Publishing Ltd.

Photoisomerization and photodissociation dynamics of reactive free radicals

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bise, Ryan T.

2000-08-01

The photofragmentation pathways of chemically reactive free radicals have been examined using the technique of fast beam photofragment translational spectroscopy. Measurements of the photodissociation cross-sections, product branching ratios, product state energy distributions, and angular distributions provide insight into the excited state potential energy surfaces and nonadiabatic processes involved in the dissociation mechanisms. Photodissociation spectroscopy and dynamics of the predissociativemore » $$\\tilde{A}$$ 2A 1 and $$\\tilde{B}$$ 2A 2 states of CH 3S have been investigated. At all photon energies, CH 3 + S( 3P j), was the main reaction channel. The translational energy distributions reveal resolved structure corresponding to vibrational excitation of the CH 3 umbrella mode and the S( 3P j) fine-structure distribution from which the nature of the coupled repulsive surfaces is inferred. Dissociation rates are deduced from the photofragment angular distributions, which depend intimately on the degree of vibrational excitation in the C-S stretch. Nitrogen combustion radicals, NCN, CNN and HNCN have also been studied. For all three radicals, the elimination of molecular nitrogen is the primary reaction channel. Excitation to linear excited triplet and singlet electronic states of the NCN radical generates resolved vibrational structure of the N 2 photofragment. The relatively low fragment rotational excitation suggests dissociation via a symmetric C 2V transition state. Resolved vibrational structure of the N 2 photofragment is also observed in the photodissociation of the HNCN radical. The fragment vibrational and rotational distributions broaden with increased excitation energy. Simple dissociation models suggest that the HNCN radical isomerizes to a cyclic intermediate (c-HCNN) which then dissociates via a tight cyclic transition state. In contrast to the radicals mentioned above, resolved vibrational structure was not observed for the ICNN radical

Quenching of I(2P1/2) by NO2, N2O4, and N2O.

PubMed

Kabir, Md Humayun; Azyazov, Valeriy N; Heaven, Michael C

2007-10-11

Quenching of excited iodine atoms (I(5p5, 2P1/2)) by nitrogen oxides are processes of relevance to discharge-driven oxygen iodine lasers. Rate constants at ambient and elevated temperatures (293-380 K) for quenching of I(2P1/2) atoms by NO2, N2O4, and N2O have been measured using time-resolved I(2P1/2) --> I(2P3/2) 1315 nm emission. The excited atoms were generated by pulsed laser photodissociation of CF3I at 248 nm. The rate constants for I(2P1/2) quenching by NO2 and N2O were found to be independent of temperature over the range examined with average values of (2.9 +/- 0.3) x 10(-15) and (1.4 +/- 0.1) x 10(-15) cm3 s(-1), respectively. The rate constant for quenching of I(2P1/2) by N2O4 was found to be (3.5 +/- 0.5) x 10(-13) cm3 s(-1) at ambient temperature.

Velocity distributions of hydrogen atoms and hydroxyl radicals produced through solar photodissociation of water

NASA Astrophysics Data System (ADS)

Wu, C. Y. R.; Chen, F. Z.

1993-04-01

The velocity distributions of H and OH fragments produced through solar photodissociation of gaseous H2O molecules under collisionless conditions are presented. The calculations are carried out using: the most recently available absolute partial cross sections for the production of H and OH through photodissociation of H2O from its absorption onset at 1860 A down to 500 A; the newly available vibrational and rotational energy distributions of both the excited and ground state OH photofragments; the calculated cross sections for the total dissociation processes; and the integrated solar flux in 10 A increments from 500 to 1860 A in the continuum regions and the specific wavelength and flux at the bright solar lines. The calculated results show that the H atoms and the OH radicals produced exhibit multiple velocity groups. Since most current cometary modeling uses a single velocity of 20 km/sec associated with the photodissociation of H2O, the present results may be useful in interpreting the many peaks observed in the velocity distributions of the H Lyman alpha and H alpha of comets.

Photodissociation in the atmosphere of Mars - Impact of high resolution, temperature-dependent CO2 cross-section measurements

NASA Technical Reports Server (NTRS)

Anbar, A. D.; Allen, M.; Nair, H. A.

1993-01-01

We have investigated the impact of high resolution, temperature-dependent CO2 cross-section measurements, reported by Lewis and Carver (1983), on calculations of photodissociation rate coefficients in the Martian atmosphere. We find that the adoption of 50 A intervals for the purpose of computational efficiency results in errors in the calculated values for photodissociation of CO2, H2O, and O2 which are generally not above 10 percent, but as large as 20 percent in some instances. These are acceptably small errors, especially considering the uncertainties introduced by the large temperature dependence of the CO2 cross section. The inclusion of temperature-dependent CO2 cross sections is shown to lead to a decrease in the diurnally averaged rate of CO2 photodissociation as large as 33 percent at some altitudes, and increases of as much as 950 percent and 80 percent in the photodissociation rate coefficients of H2O and O2, respectively. The actual magnitude of the changes depends on the assumptions used to model the CO2 absorption spectrum at temperatures lower than the available measurements, and at wavelengths longward of 1970 A.

The Development and Deployment of a Ground-Based, Laser-Induced Fluorescence Instrument for the In Situ Detection of Iodine Monoxide Radicals

NASA Technical Reports Server (NTRS)

Thurlow, M. E.; Co, D. T.; O'Brien, A. S.; Hannun, R. A.; Lapson, L. B.; Hanisco, T. F.; Anderson, J. G.

2014-01-01

High abundances of iodine monoxide (IO) are known to exist and to participate in local photochemistry of the marine boundary layer. Of particular interest are the roles IO plays in the formation of new particles in coastal marine environments and in depletion episodes of ozone and mercury in the Arctic polar spring. This paper describes a ground-based instrument that measures IO at mixing ratios less than one part in 1012. The IO radical is measured by detecting laser-induced fluorescence at wavelengths longer that 500 nm. Tunable visible light is used to pump the A23/2 (v = 2) ? X23/2 (v = 0) transition of IO near 445 nm. The laser light is produced by a solid-state, Nd:YAG-pumped Ti:Sapphire laser at 5 kHz repetition rate. The laser-induced fluorescence instrument performs reliably with very high signal-to-noise ratios (>10) achieved in short integration times (<1 min). The observations from a validation deployment to the Shoals Marine Lab on Appledore Island, ME are presented and are broadly consistent with in situ observations from European Coastal Sites. Mixing ratios ranged from the instrumental detection limit (<1 pptv) to 10 pptv. These data represent the first in situ point measurements of IO in North America.

Mathematical modeling of a photovoltaic-laser energy converter for iodine laser radiation

NASA Technical Reports Server (NTRS)

Walker, Gilbert H.; Heinbockel, John H.

1987-01-01

Space-based laser power systems will require converters to change laser radiation into electricity. Vertical junction photovoltaic converters are promising devices for this use. A promising laser for the laser power station is the t-C4F9I laser which emits radiation at a wavelength of 1.315 microns. This paper describes the results of mathematical modeling of a photovoltaic-laser energy converter for use with this laser. The material for this photovoltaic converter is Ga(53)In(47)As which has a bandgap energy of 0.94 eV, slightly below the energy of the laser photons (0.943 eV). Results of a study optimizing the converter parameters are presented. Calculated efficiency for a 1000 vertical junction converter is 42.5 percent at a power density of 1 x 10 to the 3d power w/sq cm.

Neonatal hypothyroid screening in monitoring of iodine deficiency and iodine supplementation in Poland.

PubMed

Ołtarzewski, M; Szymborski, J

2003-01-01

Neonatal hypothyroid screening in Poland is standardised and all newborns screening data are registered in central data base in the National Institute of Mother and Child. About 400,000 newborns are screened per year for hypothyroidism (TSH) and phenylketonuria (PKU). Unfortunately, obstetric clinics still use antiseptics that contain iodine. According to our data 71% of clinics used iodine in 1998 (58% iodine tincture and 13% povidone iodine) and 58.2% (35.4 iodine tincture and 13% povidone iodine) in the year 2000. Presence of iodine resulted in over 3 times increase of a percentage of TSH levels over cut off, increasing the number of false positives in the hypothyroid screening. Analysis of TSH distribution for iodine containing and iodine free hospitals gave totally different estimation of iodine deficiency according to WHO criteria. In the group of iodine free hospitals 24 regions were classified as not deficient, 9 regions were borderline with a fraction of TSH levels over 5 mlU/l of 3-5%. 10 regions could not be analysed because all hospitals declared use of iodine. In the second group all regions were iodine deficient. TSH distribution since 1994 shows significant decrease of percentage of TSH levels over cut off from 2.23% in 1994 to 0.16 in 1997 and to 0.12 in 2000. These changes are most probably connected with successive introduction of iodine supplementation which became obligatory in 1997 and suggest that iodine supplementation covers iodine requirements during pregnancy. Iodine deficiency and iodine supplementation in Poland can be studied using TSH blood spot newborn screening results in correlation with data on interfering factors and in reference to modified criteria for the analytical test and the population. To reduce false positive rate in neonatal hypothyroid screening iodine containing antiseptics, particularly iodine tincture, should be withdrawn from all obstetrics clinics in Poland.

Iodine Deficiency

MedlinePlus

... public health problem globally. Approximately 40% of the world’s population remains at risk for iodine deficiency. Iodine Deficiency ... common preventable cause of intellectual disabilities in the world. Even mild iodine ... deficiency is seen in an entire population, it is best managed by ensuring that common ...

Iodine

MedlinePlus

... the amount depends on the iodine in the soil where they grew and in any fertilizer that ... babies. People living in regions with iodine-deficient soils who eat mostly local foods. These soils produce ...

Photodissociation Spectroscopy of Anionic Transition Metal Complexes

NASA Astrophysics Data System (ADS)

Kaufman, Sydney Hamilton

Transition metal complexes play an important role in many aspects of chemistry; whether in supporting biological functions, as catalysts for organic reactions, in the environment, or in industry. This thesis is comprised of gas-phase spectroscopic studies of four transition metal species with implications for many different chemical applications. Most knowledge of the target molecules in this thesis are derived from studies in the condensed phase, where the chemical environment can change molecular properties. As a result, it is difficult to gain an understanding of the intrinsic properties in solution as well as a molecular-level picture of chemical reactions that take place where many oxidation states, molecular species, and solvent interactions occur. By isolating one particular species in the gas phase, we are able to observe how each species interacts with light independent of perturbing effects of solvent and counter ions. In this thesis, we perform spectroscopic experiments on mass-selected ions in the gas phase, where we are able to gain information on intrinsic molecular properties without the influence of a condensed phase chemical environment. We employ photodissociation spectroscopy, where we mass-select a particular ionic species from solution and irradiate that molecular ion with the output of a tunable laser in the ultraviolet and visible regions. By monitoring the fragments produced, we can obtain an electronic absorption spectrum of the isolated species as well as gain insight into the photochemistry of the ions under study from the fragmentation pathways observed. We combine this method with solution absorption spectra as well as electronic structure calculations.

Simultaneous visualization of water and hydrogen peroxide vapor using two-photon laser-induced fluorescence and photofragmentation laser-induced fluorescence.

PubMed

Larsson, Kajsa; Johansson, Olof; Aldén, Marcus; Bood, Joakim

2014-01-01

A concept based on a combination of photofragmentation laser-induced fluorescence (PF-LIF) and two-photon laser-induced fluorescence (LIF) is for the first time demonstrated for simultaneous detection of hydrogen peroxide (H2O2) and water (H2O) vapor. Water detection is based on two-photon excitation by an injection-locked krypton fluoride (KrF) excimer laser (248.28 nm), which induces broadband fluorescence (400-500 nm) from water. The same laser simultaneously photodissociates H2O2, whereupon the generated OH fragments are probed by LIF after a time delay of typically 50 ns, by a frequency-doubled dye laser (281.91 nm). Experiments in six different H2O2/H2O mixtures of known compositions show that both signals are linearly dependent on respective species concentration. For the H2O2 detection there is a minor interfering signal contribution from OH fragments created by two-photon photodissociation of H2O. Since the PF-LIF signal yield from H2O2 is found to be at least ∼24,000 times higher than the PF-LIF signal yield from H2O at room temperature, this interference is negligible for most H2O/H2O2 mixtures of practical interest. Simultaneous single-shot imaging of both species was demonstrated in a slightly turbulent flow. For single-shot imaging the minimum detectable H2O2 and H2O concentration is 10 ppm and 0.5%, respectively. The proposed measurement concept could be a valuable asset in several areas, for example, in atmospheric and combustion science and research on vapor-phase H2O2 sterilization in the pharmaceutical and aseptic food-packaging industries.

Rovibrationally-Resolved Direct Photodissociation Through The Lyman And Werner Transitions Of H_{2}

NASA Astrophysics Data System (ADS)

Gay, Christopher; Stancil, P. C.

2008-03-01

Direct photodissociation cross sections have been obtained for the Lyman and Werner transitions of H2 using a combination of ab initio and experimentally derived potential curves and dipole transition moments. The partial cross sections have been evaluated for transitions from all 301 rovibrational levels (v'',J'') of the ground electronic state and over a wavelength range that extends from 10nm to the dissociation threshold for each particular rovibrational state. For UV-irradiated molecular gas with column densities of 1016-1019cm-2, direct photodissociation can compete with the Solomon process as an H2 destruction process. This research was supported by NASA grant NNG06GJ11G from the Astrophysics Theory Program.

Research needs for assessing iodine intake, iodine status, and the effects of maternal iodine supplementation12

PubMed Central

Ershow, Abby G; Coates, Paul M; Swanson, Christine A

2016-01-01

The Office of Dietary Supplements of the NIH convened 3 workshops on iodine nutrition in Rockville, Maryland, in 2014. The purpose of the current article is to summarize and briefly discuss a list of research and resource needs developed with the input of workshop participants. This list is composed of the basic, clinical, translational, and population studies required for characterizing the benefits and risks of iodine supplementation, along with related data, analyses, evaluations, methods development, and supporting activities. Ancillary studies designed to use the participant, biological sample, and data resources of ongoing and completed studies (including those not originally concerned with iodine) may provide an efficient, cost-effective means to address some of these research and resource needs. In the United States, the foremost question is whether neurobehavioral development in the offspring of mildly to moderately iodine-deficient women is improved by maternal iodine supplementation during pregnancy. It is important to identify the benefits and risks of iodine supplementation in all population subgroups so that supplementation can be targeted, if necessary, to avoid increasing the risk of thyroid dysfunction and related adverse health effects in those with high iodine intakes. Ultimately, there will be a need for well-designed trials and other studies to assess the impact of maternal supplementation on neurodevelopmental outcomes in the offspring. However, 2 basic information gaps loom ahead of such a study: the development of robust, valid, and convenient biomarkers of individual iodine status and the identification of infant and toddler neurobehavioral development endpoints that are sensitive to mild maternal iodine deficiency during pregnancy and its reversal by supplementation. PMID:27534640

[Iodinated contrast media and iodine allergy: myth or reality?].

PubMed

Meunier, B; Joskin, J; Damas, F; Meunier, P

2013-09-01

The term "iodine allergy" is an old phrase that refers to a reaction to iodinated contrast media. After a brief review of definitions, pathophysiological mechanisms and risk factors of this clinical entity, management is urged immediate and delayed according to the most recent recommendations from the literature. We underline that iodine allergy, as such, does not really exist.

Determining median urinary iodine concentration that indicates adequate iodine intake at population level.

PubMed Central

Delange, François; de Benoist, Bruno; Burgi, Hans

2002-01-01

OBJECTIVE: Urinary iodine concentration is the prime indicator of nutritional iodine status and is used to evaluate population-based iodine supplementation. In 1994, WHO, UNICEF and ICCIDD recommended median urinary iodine concentrations for populations of 100- 200 micro g/l, assuming the 100 micro g/l threshold would limit concentrations <50 micro g/l to iodine in iodine-replete populations (schoolchildren and adults) and the proportion of concentrations <50 micro g/l. METHOD: A questionnaire on frequency distribution of urinary iodine in iodine-replete populations was circulated to 29 scientific groups. FINDINGS: Nineteen groups reported data from 48 populations with median urinary iodine concentrations >100 micro g/l. The total population was 55 892, including 35 661 (64%) schoolchildren. Median urinary iodine concentrations were 111-540 (median 201) micro g/l for all populations, 100-199 micro g/l in 23 (48%) populations and >/=200 micro g/l in 25 (52%). The frequencies of values <50 micro g/l were 0-20.8 (mean 4.8%) overall and 7.2% and 2.5% in populations with medians of 100-199 micro g/l and >200 micro g/l, respectively. The frequency reached 20% only in two places where iodine had been supplemented for <2 years. CONCLUSION: The frequency of urinary iodine concentrations <50 micro g/l in populations with median urinary iodine concentrations >/=100 micro g/l has been overestimated. The threshold of 100 micro g/l does not need to be increased. In populations, median urinary iodine concentrations of 100-200 micro g/l indicate adequate iodine intake and optimal iodine nutrition. PMID:12219154

Iodine Satellite

NASA Technical Reports Server (NTRS)

Dankanich, John; Kamhawi, Hani; Szabo, James

2015-01-01

This project is a collaborative effort to mature an iodine propulsion system while reducing risk and increasing fidelity of a technology demonstration mission concept. 1 The FY 2014 tasks include investments leveraged throughout NASA, from multiple mission directorates, as a partnership with NASA Glenn Research Center (GRC), a NASA Marshall Space Flight Center (MSFC) Technology Investment Project, and an Air Force partnership. Propulsion technology is often a critical enabling technology for space missions. NASA is investing in technologies to enable high value missions with very small and low-cost spacecraft, even CubeSats. However, these small spacecraft currently lack any appreciable propulsion capability. CubeSats are typically deployed and drift without any ability to transfer to higher value orbits, perform orbit maintenance, or deorbit. However, the iodine Hall system can allow the spacecraft to transfer into a higher value science orbit. The iodine satellite (iSAT) will be able to achieve a (Delta)V of >500 m/s with <1 kg of solid iodine propellant, which can be stored in an unpressurized benign state prior to launch. The iSAT propulsion system consists of the 200 W Hall thruster, solid iodine propellant tank, a power processing unit, and the necessary valves and tubing to route the iodine vapor. The propulsion system is led by GRC, with critical hardware provided by the Busek Co. The propellant tank begins with solid iodine unpressurized on the ground and in-flight before operations, which is then heated via tank heaters to a temperature at which solid iodine sublimates to iodine vapor. The vapor is then routed through tubing and custom valves to control mass flow to the thruster and cathode assembly. 2 The thruster then ionizes the vapor and accelerates it via magnetic and electrostatic fields, resulting in thrust with a specific impulse >1,300 s. The iSAT spacecraft, illustrated in figure 1, is currently a 12U CubeSat. The spacecraft chassis will be

Iodine in diet

MedlinePlus

... products also contain iodine. Other good sources are plants grown in iodine-rich soil. Side Effects Lack ... daily recommendations by eating seafood, iodized salt, and plants grown in iodine-rich soil. When buying salt ...

Use of iodine for water disinfection: iodine toxicity and maximum recommended dose.

PubMed Central

Backer, H; Hollowell, J

2000-01-01

Iodine is an effective, simple, and cost-efficient means of water disinfection for people who vacation, travel, or work in areas where municipal water treatment is not reliable. However, there is considerable controversy about the maximum safe iodine dose and duration of use when iodine is ingested in excess of the recommended daily dietary amount. The major health effect of concern with excess iodine ingestion is thyroid disorders, primarily hypothyroidism with or without iodine-induced goiter. A review of the human trials on the safety of iodine ingestion indicates that neither the maximum recommended dietary dose (2 mg/day) nor the maximum recommended duration of use (3 weeks) has a firm basis. Rather than a clear threshold response level or a linear and temporal dose-response relationship between iodine intake and thyroid function, there appears to be marked individual sensitivity, often resulting from unmasking of underlying thyroid disease. The use of iodine for water disinfection requires a risk-benefit decision based on iodine's benefit as a disinfectant and the changes it induces in thyroid physiology. By using appropriate disinfection techniques and monitoring thyroid function, most people can use iodine for water treatment over a prolonged period of time. PMID:10964787

Coherent control at its most fundamental: carrier-envelope-phase-dependent electron localization in photodissociation of a H2(+) molecular ion beam target.

PubMed

Rathje, T; Sayler, A M; Zeng, S; Wustelt, P; Figger, H; Esry, B D; Paulus, G G

2013-08-30

Measurements and calculations of the absolute carrier-envelope-phase (CEP) effects in the photodissociation of the simplest molecule, H2(+), with a 4.5-fs Ti:sapphire laser pulse at intensities up to (4±2)×10(14)  W/cm2 are presented. Localization of the electron with respect to the two nuclei (during the dissociation process) is controlled via the CEP of the ultrashort laser pulses. In contrast to previous CEP-dependent experiments with neutral molecules, the dissociation of the molecular ions is not preceded by a photoionization process, which strongly influences the CEP dependence. Kinematically complete data are obtained by time- and position-resolved coincidence detection. The phase dependence is determined by a single-shot phase measurement correlated to the detection of the dissociation fragments. The experimental results show quantitative agreement with ab initio 3D time-dependent Schrödinger equation calculations that include nuclear vibration and rotation.

Carbon recombination lines as a diagnostic of photodissociation regions

NASA Technical Reports Server (NTRS)

Natta, A.; Walmsley, C. M.; Tielens, A. G. G. M.

1994-01-01

We have observed the C91 alpha radio recombination line toward the Orion H II region. This narrow (approximately 3-5 km per sec full width at half maximum (FWHM)) line is spatially very extended (approximately 8 arcmin or 1 pc). These charateristics compare well with the observed characteristics of the C II fine structure line at 158 microns. Thus, the C91 alpha line originates in the predominantly neutral photodissociation regions separating the H II region from the molecular cloud. We have developed theoretical models for the C II radio recombination lines from photodissociation regions. The results show that the I(C91 alpha)/I(C158) intensity ratio is a sensitive function of the temperature and density of the emitting gas. We have also extended theoretical models for photodissociation regions to include the C II recombination lines. Comparison with these models show that, in the central portion of the Orion region, the C91 alpha line originates in dense (10(exp 6) per cu cm), warm (500-1000 K) gas. Even at large projected distances (approximately 1 pc), the inferred density is still high (10(exp 5) per cu cm) and implies extremely high thermal pressures. As in the case of the (C II) 158 microns line, the large extent of the C91 alpha line shows that (FUV) photons can penetrate to large distances from the illuminating source. The decline of the intensity of the incident radiation field with distance from Theta(sup 1) C seems to be dominated by geometrical dilution, rather than dust extinction. Finally, we have used our models to calculate the intensity of the 9850 A recombination line of C II. The physical conditions inferred from this line are in good agreement with those determined from the radio recombination and the far-infrared fine-structure lines. We show that the ratio of the 9850 A to the C91 alpha lines is a very good probe of very high density clumps.

Proceedings of Workshop on Laser Diagnostics in Fluid Mechanics and Combustion

NASA Astrophysics Data System (ADS)

1993-10-01

Proceedings of the Workshop on Laser Diagnostics in Fluid Mechanics and Combustion are presented. Topics included are: Accuracy of Laser Doppler Anemometry; Applications of Raman-Rayleigh-LIF Diagnostics in Combustion Research; Phase Doppler Anemometer Technique Concepts and Applications; CARS; Particle Image Velocimetry; Practical Consideration in the Use and Design of Laser Velocimetry Systems in Turbomachinery Applications; Phase Doppler Measurements of Gas-Particle Flow Through a Tube Bank; Degenerate Four Wave Mixing for Shock Tunnel Studies of Supersonic Combustion; Laser Induced Photodissociation and Fluorescence (LIPF) of Sodium Species Present in Coal Combustion; 3D Holographic Measurements Inside a Spark Ignition Engine; Laser Doppler Velocimeter Measurements in Compressible Flow; Bursting in a Tornado Vortex; Quantitative Imaging of OH and Temperature Using a Single Laser Source and Single Intensified Camera; and Laser Doppler Measurements Inside an Artificial Heart Valve.

Optically-Based Diagnostics for Gas-Phase Laser Development

DTIC Science & Technology

2010-08-01

Laser (COIL), Electric Oxygen Iodine Laser (EOIL), Diode-Pumped Alkali Laser (DPAL), and Exciplex Alkali Laser (XPAL). The papers at this Symposium... exciplex -assisted absorption and laser-induced fluorescence, and multi-photon excitation of infrared atomic alkali transitions.11,12 In this paper... EXCIPLEX LASER SYSTEMS Proper review and discussion of the DPAL and XPAL laser systems can be found elsewhere,11,12 and in the paper by Carroll and

The elementary steps of the photodissociation and recombination reactions of iodine molecules enclosed in cages and channels of zeolite crystals: a femtosecond time-resolved study of the geometry effect.

PubMed

Flachenecker, G; Materny, A

2004-03-22

We present femtosecond time-resolved pump-probe experiments on iodine molecules enclosed into well-defined cages and channels of different crystalline SiO2 modifications of zeolites. The new experimental results obtained from iodine in TON (Silica-ZSM-22), FER (Silica-Ferrierit), and MFI (Silicalit-1) porosils are compared with data published earlier on the iodine/DDR (Decadodecasil 3R) porosil system [Flachenecker et al., Phys. Chem. Chem. Phys. 5, 865 (2003)]. A summary of all findings is given. The processes analyzed by means of the ultrafast spectroscopy are the vibrational relaxation as well as the dissociation and recombination reactions, which are caused by the interaction of the photo-excited iodine molecules with the cavity walls of the porosils. A clear dependence of the observed dynamics on the geometry of the surrounding lattice structure can be seen. These measurements are supported by temperature-dependent experiments. Making use of a theoretical model which is based on the classical Langevin equation, an analysis of the geometry-reaction relation is performed. The Brownian dynamics simulations show that in contrast to the vibrational relaxation the predissociation dynamics are independent of the frequency of collisions with the surroundings. From the results obtained in the different surroundings, we conclude that mainly local fields are responsible for the crossing from the bound B state to the repulsive a/a' states of the iodine molecules.

The Urine Iodine to Creatinine as an Optimal Index of Iodine During Pregnancy in an Iodine Adequate Area in China.

PubMed

Li, Chenyan; Peng, Shiqiao; Zhang, Xiaomei; Xie, Xiaochen; Wang, Danyang; Mao, Jinyuan; Teng, Xiaochun; Shan, Zhongyan; Teng, Weiping

2016-03-01

Iodine nutrition is a global event, especially for pregnant women. To develop applicable index of iodine intake for population during pregnancy. From 2012 to 2014, pregnant women at less than 8 weeks of gestation (n = 222) and reproductive-age women (n = 827) participated in this study. The pregnant women were evaluated at follow-up visits at 8, 12, 16, 20, 28, and 36 weeks of gestation and 3 and 6 months postpartum. Twenty-four-hour urine samples were collected at weeks 8 of gestation. Urine iodine (UI) and creatinine (Cr) and serum thyroglobulin were measured in all of the subjects. Circulatory iodine was measured using inductively coupled plasma-mass spectrometry at 8, 20, and 36 weeks of gestation and 6 months postpartum. The median UI concentration decreased from 183.6 to 104.2 μg/L during pregnancy. The serum iodine (SI) changes were similar to the UI to creatinine ratio (UI/Cr). The SI level was lowest at the eighth week of gestation (60.5 μg/L), which rose significantly until 20 weeks (106.5 μg/L) and then began to decline (36 wk, 84.7 μg/L). The 24-hour UI excretion measurement was regarded as the gold standard. The area under the receiver-operating characteristic curve for UI/Cr was 0.92 for iodine deficiency diagnoses and 0.78 for SI. The area for SI was 0.82 for excessive iodine diagnoses and 0.75 for UI/Cr. The areas under these curves were significantly different (P < .001). The areas under the receiver-operating characteristic curve for UI were 0.61 (P = .11) and 0.65 (P = .08) for iodine deficiency and excessive iodine diagnoses, respectively. Additionally, for thyroglobulin, these values were 0.54 (P = .53) and 0.53 (P = .74), respectively. Iodine intake, as assessed by spot UI concentration in pregnant women, is inaccurate and increases the prevalence of iodine deficiency. The UI/Cr better reflects the 24-hour iodine excretion and circulating iodine levels during pregnancy and the postpartum period.

Stability of iodine in salt fortified with iodine and iron.

PubMed

Ranganathan, Srinivasaiyengar; Karmarkar, Madhu G; Krupadanam, Muddepaka; Brahmam, Ginnela N V; Rao, Mendhu Vishnuvardhana; Vijayaraghavan, Kamasamudram; Sivakumar, Bhattriprolu

2007-03-01

Determining the stability of iodine in fortified salt can be difficult under certain conditions. Current methods are sometimes unreliable in the presence of iron. To test the new method to more accurately estimate iodine content in double-fortified salt (DFS) fortified with iodine and iron by using orthophosphoric acid instead of sulfuric acid in the titration procedure. A double-blind, placebo-controlled study was carried out on DFS and iodized salt produced by the dry-mixing method. DFS and iodized salt were packed and sealed in color-coded, 0.5-kg, low-density polyethylene pouches, and 25 of these pouches were further packed and sealed in color-coded, double-lined, high-density polyethylene bags and transported by road in closed, light-protected containers to the International Council for the Control of Iodine Deficiency Disorders (ICCIDD), Delhi; the National Institute of Nutrition (NIN), Hyderabad; and the Orissa Unit of the National Nutrition Monitoring Bureau (NNMB), Bhubaneswar. The iodine content of DFS and iodized salt stored under normal room conditions in these places was measured by the modified method every month on the same prescribed dates during the first 6 months and also after 15 months. The iodine content of DFS and iodized salt stored under simulated household conditions was also measured in the first 3 months. After the color code was broken at the end of the study, it was found that the DFS and iodized salt stored at Bhubaneswar, Delhi, and Hyderabad retained more or less the same initial iodine content (30-40 ppm) during the first 6 months, and the stability was not affected after 15 months. The proportion of salt samples having more than 30 ppm iodine was 100% in DFS and iodized salt throughout the study period. Daily opening and closing of salt pouches under simulated household conditions did not result in any iodine loss. The DFS and iodized salt prepared by the dry-mixing method and stored at normal room conditions had excellent iodine

Iodine generator for reclaimed water purification

NASA Technical Reports Server (NTRS)

Wynveen, R. A.; Powell, J. D.; Schubert, F. H. (Inventor)

1977-01-01

The system disclosed is for controlling the iodine level in a water supply in a spacecraft. It includes an iodine accumulator which stores crystalline iodine, an electrochemical valve to control the input of iodine to the drinking water and an iodine dispenser. A pump dispenses fluid through the iodine dispenser and an iodine sensor to a potable water tank storage. The iodine sensor electronically detects the iodine level in the water, and through electronic means, produces a correction current control. The correction current control operates the electro-chemical iodine valve to release iodine from the iodine accumulator into the iodine dispenser.

Data acquisition and control system with a programmable logic controller (PLC) for a pulsed chemical oxygen-iodine laser

NASA Astrophysics Data System (ADS)

Yu, Haijun; Li, Guofu; Duo, Liping; Jin, Yuqi; Wang, Jian; Sang, Fengting; Kang, Yuanfu; Li, Liucheng; Wang, Yuanhu; Tang, Shukai; Yu, Hongliang

2015-02-01

A user-friendly data acquisition and control system (DACS) for a pulsed chemical oxygen -iodine laser (PCOIL) has been developed. It is implemented by an industrial control computer，a PLC, and a distributed input/output (I/O) module, as well as the valve and transmitter. The system is capable of handling 200 analogue/digital channels for performing various operations such as on-line acquisition, display, safety measures and control of various valves. These operations are controlled either by control switches configured on a PC while not running or by a pre-determined sequence or timings during the run. The system is capable of real-time acquisition and on-line estimation of important diagnostic parameters for optimization of a PCOIL. The DACS system has been programmed using software programmable logic controller (PLC). Using this DACS, more than 200 runs were given performed successfully.

Ultraviolet photodissociation dynamics of the benzyl radical.

PubMed

Song, Yu; Zheng, Xianfeng; Lucas, Michael; Zhang, Jingsong

2011-05-14

Ultraviolet (UV) photodissociation dynamics of jet-cooled benzyl radical via the 4(2)B(2) electronically excited state is studied in the photolysis wavelength region of 228 to 270 nm using high-n Rydberg atom time-of-flight (HRTOF) and resonance enhanced multiphoton ionization (REMPI) techniques. In this wavelength region, H-atom photofragment yield (PFY) spectra are obtained using ethylbenzene and benzyl chloride as the precursors of benzyl radical, and they have a broad peak centered around 254 nm and are in a good agreement with the previous UV absorption spectra of benzyl. The H + C(7)H(6) product translational energy distributions, P(E(T))s, are derived from the H-atom TOF spectra. The P(E(T)) distributions peak near 5.5 kcal mol(-1), and the fraction of average translational energy in the total excess energy, , is ∼0.3. The P(E(T))s indicate the production of fulvenallene + H, which was suggested by recent theoretical studies. The H-atom product angular distribution is isotropic, with the anisotropy parameter β ≈ 0. The H/D product ratios from isotope labeling studies using C(6)H(5)CD(2) and C(6)D(5)CH(2) are reasonably close to the statistical H/D ratios, suggesting that the H/D atoms are scrambled in the photodissociation of benzyl. The dissociation mechanism is consistent with internal conversion of the electronically excited benzyl followed by unimolecular decomposition of the hot benzyl radical on the ground state.

Iodination and stability of somatostatin analogues: comparison of iodination techniques. A practical overview.

PubMed

de Blois, Erik; Chan, Ho Sze; Breeman, Wouter A P

2012-01-01

For iodination ((125/127)I) of tyrosine-containing peptides, chloramin-T, Pre-Coated Iodo-Gen(®) tubes and Iodo-Beads(®) (Pierce) are commonly used for in vitro radioligand investigations and there have been reliant vendors hereof for decades. However, commercial availability of these radio-iodinated peptides is decreasing. For continuation of our research in this field we investigated and optimized (radio-)iodination of somatostatin analogues. In literature, radioiodination using here described somatostatin analogues and iodination techniques are described separately. Here we present an overview, including High Performance Liquid Chromatography (HPLC) separation and characterisation by mass spectrometry, to obtain mono- and di-iodinated analogues. Reaction kinetics of (125/127)I iodinated somatostatin analogues were investigated as function of reaction time and concentration of reactants, including somatostatin analogues, iodine and oxidizing agent. To our knowledge, for the here described somatostatin analogues, no (127)I iodination and optimization are described. (Radio-)iodinated somatostatin analogues could be preserved with a >90% radiochemical purity for 1 month after reversed phase HPLC-purification.

Effect of iodine disinfectant source and water quality parameters on soluble iodine speciation

NASA Technical Reports Server (NTRS)

Silverstein, Joann; Hurst, Charles; Barkley, Robert; Dunham, Andrew

1993-01-01

Investigations of iodine species distribution of various aqueous solutions of iodine disinfectants and water from equilibrated suspensions of triodide and pentaiodide resins were done at the University of Colorado for the Center for Space Environmental Health during 1992 and 1993. Direct measurements of three individual iodine species: I(-), I2 and I3(-), were made. In addition three measures of total titratable iodine species were used. It has been found that I2 and I3(-) solutions produce a significant fraction of the non-disinfecting species iodine I(-), ranging from 50 to 80% of added iodine, respectively, at pH values of approximately 5. Correspondingly, I2 solutions produce more than twice the concentration of disinfecting iodine species per mass iodine dose than I3(-) solutions. Both I(-) and I2 species were found in aqeuous extracts of pentaiodide resin, although no soluble species were detected with triiodide resin.

Modeling an Iodine Hall Thruster Plume in the Iodine Satellite (ISAT)

NASA Technical Reports Server (NTRS)

Choi, Maria

2016-01-01

An iodine-operated 200-W Hall thruster plume has been simulated using a hybrid-PIC model to predict the spacecraft surface-plume interaction for spacecraft integration purposes. For validation of the model, the plasma potential, electron temperature, ion current flux, and ion number density of xenon propellant were compared with available measurement data at the nominal operating condition. To simulate iodine plasma, various collision cross sections were found and used in the model. While time-varying atomic iodine species (i.e., I, I+, I2+) information is provided by HP Hall simulation at the discharge channel exit, the molecular iodine species (i.e., I2, I2+) are introduced as Maxwellian particles at the channel exit. Simulation results show that xenon and iodine plasma plumes appear to be very similar under the assumptions of the model. Assuming a sticking coefficient of unity, iodine deposition rate is estimated.

Modeling an Iodine Hall Thruster Plume in the Iodine Satellite (ISAT)

NASA Technical Reports Server (NTRS)

Choi, Maria

2016-01-01

An iodine-operated 200-W Hall thruster plume has been simulated using a hybrid-PIC model to predict the spacecraft surface-plume interaction for spacecraft integration purposes. For validation of the model, the plasma potential, electron temperature, ion current flux, and ion number density of xenon propellant were compared with available measurement data at the nominal operating condition. To simulate iodine plasma, various collision cross sections were found and used in the model. While time-varying atomic iodine species (i.e., I, I+, I2+) information is provided by HPHall simulation at the discharge channel exit, the molecular iodine species (i.e., I2, I2+) are introduced as Maxwellian particles at the channel exit. Simulation results show that xenon and iodine plasma plumes appear to be very similar under the assumptions of the model. Assuming a sticking coefficient of unity, iodine deposition rate is estimated.

Low-level seaweed supplementation improves iodine status in iodine-insufficient women.

PubMed

Combet, Emilie; Ma, Zheng Feei; Cousins, Frances; Thompson, Brett; Lean, Michael E J

2014-09-14

Iodine insufficiency is now a prominent issue in the UK and other European countries due to low intakes of dairy products and seafood (especially where iodine fortification is not in place). In the present study, we tested a commercially available encapsulated edible seaweed (Napiers Hebridean Seagreens® Ascophyllum nodosum species) for its acceptability to consumers and iodine bioavailability and investigated the impact of a 2-week daily seaweed supplementation on iodine concentrations and thyroid function. Healthy non-pregnant women of childbearing age, self-reporting low dairy product and seafood consumption, with no history of thyroid or gastrointestinal disease were recruited. Seaweed iodine (712 μg, in 1 g seaweed) was modestly bioavailable at 33 (interquartile range (IQR) 28-46) % of the ingested iodine dose compared with 59 (IQR 46-74) % of iodine from the KI supplement (n 22). After supplement ingestion (2 weeks, 0·5 g seaweed daily, n 42), urinary iodine excretion increased from 78 (IQR 39-114) to 140 (IQR 103-195) μg/l (P< 0·001). The concentrations of thyroid-stimulating hormone increased from 1·5 (IQR 1·2-2·2) to 2·1 (IQR 1·3-2·9) mIU/l (P< 0·001), with two participants having concentrations exceeding the normal range after supplement ingestion (but normal free thyroxine concentrations). There was no change in the concentrations of other thyroid hormones after supplement ingestion. The seaweed was palatable and acceptable to consumers as a whole food or as a food ingredient and effective as a source of iodine in an iodine-insufficient population. In conclusion, seaweed inclusion in staple foods would serve as an alternative to fortification of salt or other foods with KI.

Photodissociation Dynamics of Phenol: Multistate Trajectory Simulations including Tunneling

DOE PAGES

Xu, Xuefei; Zheng, Jingjing; Yang, Ke R.; ...

2014-10-27

We report multistate trajectory simulations, including coherence, decoherence, and multidimensional tunneling, of phenol photodissociation dynamics. The calculations are based on full-dimensional anchor-points reactive potential surfaces and state couplings fit to electronic structure calculations including dynamical correlation with an augmented correlation-consistent polarized valence double-ζ basis set. The calculations successfully reproduce the experimentally observed bimodal character of the total kinetic energy release spectra and confirm the interpretation of the most recent experiments that the photodissociation process is dominated by tunneling. Analysis of the trajectories uncovers an unexpected dissociation pathway for one quantum excitation of the O–H stretching mode of the S 1more » state, namely, tunneling in a coherent mixture of states starting in a smaller R OH (~0.9–1.0 Å) region than has previously been invoked. The simulations also show that most trajectories do not pass close to the S 1–S 2 conical intersection (they have a minimum gap greater than 0.6 eV), they provide statistics on the out-of-plane angles at the locations of the minimum energy adiabatic gap, and they reveal information about which vibrational modes are most highly activated in the products.« less

[Study on the iodine nutrition and iodine deficiency disorders status in pasturing areas of Tibet-a non-epidemic area of iodine deficiency disorders in serious iodine deficiency district].

PubMed

DU, Dan; Li, Su-Mei; Li, Xiu-Wei; Wang, Hai-Yan; Li, Shu-Hua; Nima, Cangjue; Danzeng, Sangbu; Zhuang, Guang-Xiu

2010-08-01

To explore the status of iodine nutrition and iodine deficiency disorders in the pasturing areas and agricultural regions in Tibet. 30 families were selected respectively in pastoral Dangxiong county and agricultural Qushui county of Lasa. Drinking water and edible salt were collected for testing the iodine contents. In each type of the following populations including children aged 8 - 10, women of child-bearing age and male adults, 50 subjects were randomly sampled to examine their urinary iodine contents. Among them, 50 children and 50 women were randomly selected for goiter examination by palpation. Water iodine content was less than 2 µg/L, both in pasturing area and in agricultural areas. There was no iodized salt used in the families of pasturing areas, while 90% people consumed iodized salt in agricultural areas. The median of urinary iodine in pasturing area was 50.2 µg/L, significantly lower than that of agricultural area (193.2 µg/L). However, the goiter rate of children and women in pasturing area was significantly lower than that in agricultural area. Although iodine intake of populations in pasturing area of Tibet was severely deficient, there was no epidemic of Iodine Deficiency Disorders. This phenomenon noticed by the researchers deserved further investigation.

Photodissociation dynamics of Mo(CO) sub 6 at 266 and 355 nm: CO photofragment kinetic-energy and internal-state distributions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Buntin, S.A.; Cavanagh, R.R.; Richter, L.J.

1991-06-15

The internal-state and kinetic-energy distributions of the CO photofragments from the 266 and 355 nm photolysis of Mo(CO){sub 6} have been measured under collision-free conditions using vacuum-ultraviolet laser-induced fluorescence. The rotational-state distributions for CO({ital v}{double prime}=0) and ({ital v}{double prime}=1) are well represented by Boltzmann distributions with effective rotational temperatures'' of {ital T}{sub {ital r}}({ital v}{double prime}=0)=950{plus minus}70 K and {ital T}{sub {ital r}}({ital v}{double prime}=1)=935{plus minus}85 K for 266 nm and {ital T}{sub {ital r}}({ital v}{double prime}=0)=750{plus minus}70 K and {ital T}{sub {ital r}}({ital v}{double prime}=1)=1150{plus minus}250 K for 355 nm photolysis. The CO({ital v}{double prime}=1/{ital v}{double prime}=0) vibrational-statemore » ratios for 266 and 355 nm photolysis are 0.19{plus minus}0.03 and 0.09{plus minus}0.02, respectively. The Doppler-broadened CO photofragment line shapes indicate that the translational energy distributions are isotropic and Maxwellian. There is no photolysis-laser wavelength or internal-state dependence to the extracted translational temperatures.'' The observed energy partitioning and kinetic-energy distributions are inconsistent with an impulsive ejection of a single CO ligand. CO photofragment line shapes for 266 nm photolysis are not consistent with a mechanism involving the repulsive ejection of the first CO ligand, followed by the statistical decomposition of the Mo(CO){sub 5} fragment. While phase-space theories do not predict quantitatively the energy disposal, the photodissociation mechanism appears to be dominated by statistical considerations. The results also suggest that the photodissociation of Mo(CO){sub 6} at 266 and 355 nm involves a common initial state'' and that similar exit channel effects are operative.« less

Iodine deficiency and thyroid disorders.

PubMed

Zimmermann, Michael B; Boelaert, Kristien

2015-04-01

Iodine deficiency early in life impairs cognition and growth, but iodine status is also a key determinant of thyroid disorders in adults. Severe iodine deficiency causes goitre and hypothyroidism because, despite an increase in thyroid activity to maximise iodine uptake and recycling in this setting, iodine concentrations are still too low to enable production of thyroid hormone. In mild-to-moderate iodine deficiency, increased thyroid activity can compensate for low iodine intake and maintain euthyroidism in most individuals, but at a price: chronic thyroid stimulation results in an increase in the prevalence of toxic nodular goitre and hyperthyroidism in populations. This high prevalence of nodular autonomy usually results in a further increase in the prevalence of hyperthyroidism if iodine intake is subsequently increased by salt iodisation. However, this increase is transient because iodine sufficiency normalises thyroid activity which, in the long term, reduces nodular autonomy. Increased iodine intake in an iodine-deficient population is associated with a small increase in the prevalence of subclinical hypothyroidism and thyroid autoimmunity; whether these increases are also transient is unclear. Variations in population iodine intake do not affect risk for Graves' disease or thyroid cancer, but correction of iodine deficiency might shift thyroid cancer subtypes toward less malignant forms. Thus, optimisation of population iodine intake is an important component of preventive health care to reduce the prevalence of thyroid disorders. Copyright © 2015 Elsevier Ltd. All rights reserved.

Suboptimal Iodine Concentration in Breastmilk and Inadequate Iodine Intake among Lactating Women in Norway.

PubMed

Henjum, Sigrun; Lilleengen, Anne Marie; Aakre, Inger; Dudareva, Anna; Gjengedal, Elin Lovise Folven; Meltzer, Helle Margrete; Brantsæter, Anne Lise

2017-06-22

Breastfed infants depend on sufficient maternal iodine intake for optimal growth and neurological development. Despite this, few studies have assessed iodine concentrations in human milk and there is currently no published data on iodine status among lactating women in Norway. The aim of this study was to assess iodine concentrations in breast milk (BMIC) in lactating women and estimate iodine intake. Five Mother and Child Health Centres in Oslo were randomly selected during 2016, and 175 lactating women between 2nd and 28th weeks postpartum participated. Each of the women provided four breastmilk samples which were pooled and analysed for iodine concentrations. Participants also provided information on iodine intake from food and supplements covering the last 24 h and the habitual iodine intake (food frequency questionnaire). The median (p25, p75 percentiles) BMIC was 68 (45, 98) µg/L and 76% had BMIC <100 µg/L. Only 19% had taken an iodine-containing supplement during the last 24 h. The median 24 h iodine intake from food (p25, p75) was 121 (82, 162) µg/day and the total intake (food and supplements) was 134 (95, 222) µg/day. The majority of lactating women had suboptimal BMIC and inadequate intake of iodine from food and supplements.

Suboptimal Iodine Concentration in Breastmilk and Inadequate Iodine Intake among Lactating Women in Norway

PubMed Central

Henjum, Sigrun; Lilleengen, Anne Marie; Aakre, Inger; Dudareva, Anna; Gjengedal, Elin Lovise Folven; Meltzer, Helle Margrete; Brantsæter, Anne Lise

2017-01-01

Breastfed infants depend on sufficient maternal iodine intake for optimal growth and neurological development. Despite this, few studies have assessed iodine concentrations in human milk and there is currently no published data on iodine status among lactating women in Norway. The aim of this study was to assess iodine concentrations in breast milk (BMIC) in lactating women and estimate iodine intake. Five Mother and Child Health Centres in Oslo were randomly selected during 2016, and 175 lactating women between 2nd and 28th weeks postpartum participated. Each of the women provided four breastmilk samples which were pooled and analysed for iodine concentrations. Participants also provided information on iodine intake from food and supplements covering the last 24 h and the habitual iodine intake (food frequency questionnaire). The median (p25, p75 percentiles) BMIC was 68 (45, 98) µg/L and 76% had BMIC <100 µg/L. Only 19% had taken an iodine-containing supplement during the last 24 h. The median 24 h iodine intake from food (p25, p75) was 121 (82, 162) µg/day and the total intake (food and supplements) was 134 (95, 222) µg/day. The majority of lactating women had suboptimal BMIC and inadequate intake of iodine from food and supplements. PMID:28640217

Studies of new media radiation induced laser. Final Report, 1 February 1979-30 April 1984

DOE Office of Scientific and Technical Information (OSTI.GOV)

Han, K.S.; Shiu, Y.J.; Raju, S.R.

Various lasants were investigated especially, 2-iodohepafluoropropane (i-C3F7I) for the direct solar pumped lasers. Optical pumping of iodine laser was achieved using a small flashlamp. Using i-C3F7I as a laser gain medium, threshold inversion density, small signal gain, and laser performance at the elevated temperature were measured. The experimental results and analysis are presented. The iodine laser kinetics of the C3F7I and IBr system were numerically simulated. The concept of a direct solar-pumped laser amplifier using (i-C3F7I) as the laser material was evaluated and several kinetic coefficients for i-C3F7I laser system were reexamined. The results are discussed.

An ultra-stable iodine-based frequency reference for space applications

NASA Astrophysics Data System (ADS)

Schuldt, Thilo; Braxmaier, Claus; Doeringshoff, Klaus; Keetman, Anja; Reggentin, Matthias; Kovalchuk, Evgeny; Peters, Achim

2012-07-01

Future space missions require for ultra-stable optical frequency references. Examples are the gravitational wave detector LISA/eLISA (Laser Interferometer Space Antenna), the SpaceTime Asymmetry Research (STAR) program, the aperture-synthesis telescope Darwin and the GRACE (Gravity Recovery and Climate Experiment) follow on mission exploring Earth's gravity. As high long-term frequency stability is required, lasers stabilized to atomic or molecular transitions are preferred, also offering an absolute frequency reference. Frequency stabilities in the 10 ^{-15} domains at longer integration times (up to several hours) are demonstrated in laboratory experiments using setups based on Doppler-free spectroscopy. Such setups with a frequency stability comparable to the hydrogen maser in the microwave domain, have the potential to be developed space compatible on a relatively short time scale. Here, we present the development of ultra-stable optical frequency references based on modulation-transfer spectroscopy of molecular iodine. Noise levels of 2\\cdot10 ^{-14} at an integration time of 1 s and below 3\\cdot10 ^{-15} at integration times between 100 s and 1000 s are demonstrated with a laboratory setup using an 80 cm long iodine cell in single-pass configuration in combination with a frequency-doubled Nd:YAG laser and standard optical components and optomechanic mounts. The frequency stability at longer integration times is (amongst other things) limited by the dimensional stability of the optical setup, i.e. by th pointing stability of the two counter-propagating beams overlapped in the iodine cell. With the goal of a future space compatible setup, a compact frequency standard on EBB (elegant breadboard) level was realized. The spectroscopy unit utilizes a baseplate made of Clearceram-HS, a glass ceramics with an ultra-low coefficient of thermal expansion of 2\\cdot10 ^{-8} K ^{-1}. The optical components are joint to the baseplate using adhesive bonding technology

Precision Atomic Beam Laser Spectroscopy

DTIC Science & Technology

1999-02-20

optical efficiency with a new coupled- cavity scheme. We have locked a MISER Nd:YAG laser to a finesse 50,000 cavity with a...sensitivity of optical heterodyne detection is preserved with ZERO sensitivity to small laser / cavity frequency noises. The new method is called Noise-Immune...1996), P. Dube, L.- S. Ma, J. Ye, and J.L.Hall. 9 . "Free-induction decay in molecular iodine measured with an extended - cavity diode laser ,"

Transition state region in the A-Band photodissociation of allyl iodide—A femtosecond extreme ultraviolet transient absorption study

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bhattacherjee, Aditi, E-mail: abhattacherjee@berkeley.edu, E-mail: andrewattar@berkeley.edu; Attar, Andrew R., E-mail: abhattacherjee@berkeley.edu, E-mail: andrewattar@berkeley.edu; Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720

2016-03-28

Femtosecond extreme ultraviolet (XUV) transient absorption spectroscopy based on a high-harmonic generation source is used to study the 266 nm induced A-band photodissociation dynamics of allyl iodide (CH{sub 2} =CHCH{sub 2}I). The photolysis of the C—I bond at this wavelength produces iodine atoms both in the ground ({sup 2}P{sub 3/2}, I) and spin-orbit excited ({sup 2}P{sub 1/2}, I*) states, with the latter as the predominant channel. Using XUV absorption at the iodine N{sub 4/5} edge (45–60 eV), the experiments constitute a direct probe of not only the long-lived atomic iodine reaction products but also the fleeting transition state region ofmore » the repulsive n{sub I}σ{sup ∗}{sub C—I} excited states. Specifically, three distinct features are identified in the XUV transient absorption spectrum at 45.3 eV, 47.4 eV, and 48.4 eV (denoted transients A, B, and C, respectively), which arise from the repulsive valence-excited nσ{sup ∗} states and project onto the high-lying core-excited states of the dissociating molecule via excitation of 4d(I) core electrons. Transients A and B originate from 4d(I) → n(I) core-to-valence transitions, whereas transient C is best assigned to a 4d(I) →σ{sup ∗}(C—I) transition. The measured differential absorbance of these new features along with the I/I* branching ratios known from the literature is used to suggest a more definitive assignment, albeit provisional, of the transients to specific dissociative states within the A-band manifold. The transients are found to peak around 55 fs–65 fs and decay completely by 145 fs–185 fs, demonstrating the ability of XUV spectroscopy to map the evolution of reactants into products in real time. The similarity in the energies of transients A and B with analogous features observed in methyl iodide [Attar et al. J. Phys. Chem. Lett. 6, 5072, (2015)] together with the new observation of transient C in the present work provides a more complete picture of the valence

Iodine chemistry in the water column of the Chesapeake Bay: Evidence for organic iodine forms

NASA Astrophysics Data System (ADS)

Luther, George W.; Ferdelman, Timothy; Culberson, Charles H.; Kostka, Joel; Wu, Jingfeng

1991-03-01

During the summer of 1987, we collected and analysed Chesapeake Bay water samples for the inorganic iodine species: iodide (by cathodic-stripping squarewave voltammetry) and iodate (by differential pulse polarography); and total iodine (by hypochlorite oxidation of the seawater sample to iodate). The difference between the sum of the inorganic iodine species and the total iodine was significant for about one-third of the samples collected from the Bay. Thus, in these samples, a third (or more) 'new' form(s) of iodine was present. These samples were primarily from oxygen-saturated surface waters of high biological activity (primary productivity and bacterial processes). This 'new' form can make up as much as 70% of the total iodine. Waters containing low oxygen concentrations showed less of this 'new' form of iodine whereas anoxic and sulphidic bottom waters contained only iodide. This 'new' form of iodine is organic in nature and probably non-volatile. It may reside in the peptide and humic fractions. Only reduced iodine (iodide and organic iodine) was detected in waters from the northern section of the Bay, whereas only iodide and iodate were detected in the southern section of the Bay. In only two samples were iodide, iodate and the 'new' form of iodine found to coexist. Iodide and organic iodine are probably cycled in the surface waters of the northern section of the Bay via a combination of biogeochemical and photochemical processes which produce the reactive intermediates, molecular iodine and hypoiodous acid. These react quickly with reduced inorganic and organic compounds to maintain the reduced forms of iodine in the water column. Only total iodine is conservative throughout the estuary. The inorganic iodine forms can be used as geochemical tracers.

FDA regulations regarding iodine addition to foods and labeling of foods containing added iodine.

PubMed

Trumbo, Paula R

2016-09-01

The US Food and Drug Administration (FDA) regulates the addition of iodine to infant formulas, the iodization of salt, and the addition of salt and iodine to foods. The required amount of iodine in infant formulas is based on caloric content, and the label must provide the iodine content per 100 kcal. Cuprous iodide and potassium iodide may be added to table salt as a source of dietary iodine at a maximum amount of 0.01%; if added, the label must indicate that the salt is iodized. Table salt to which iodine has not been added must bear the statement, "This salt does not supply iodide, a necessary nutrient." If a nutrient is to be appropriately added to a food for the purpose of correcting a dietary insufficiency, there should be sufficient scientific information available to demonstrate a nutritional deficiency and/or identify a public health problem. Furthermore, the population groups that would benefit from the proposed fortification should be identified. If iodine is added to a food, the percent Daily Value of iodine must be listed. There are no FDA regulations governing ingredient standards for dietary supplements. As a result, some dietary supplements include iodine and others do not. If a supplement contains iodine, the Supplement Facts label must list iodine as a nutrient ingredient. If iodine is not listed on the Supplement Facts label, then it has not been added. There are similarities between the FDA, which establishes US food regulations and policies, and the Codex Alimentarius (Codex), which develops international food standards and guidelines under the aegis of the FAO and the WHO. Both the FDA and Codex call for the labeling of table salt to indicate fortification with iodine, voluntary labeling of iodine on foods, and a Daily Value (called a Nutrient Reference Value by Codex) of 150 μg for iodine. © 2016 American Society for Nutrition.

Iodine Hall Thruster

NASA Technical Reports Server (NTRS)

Szabo, James

2015-01-01

Iodine enables dramatic mass and cost savings for lunar and Mars cargo missions, including Earth escape and near-Earth space maneuvers. The demonstrated throttling ability of iodine is important for a singular thruster that might be called upon to propel a spacecraft from Earth to Mars or Venus. The ability to throttle efficiently is even more important for missions beyond Mars. In the Phase I project, Busek Company, Inc., tested an existing Hall thruster, the BHT-8000, on iodine propellant. The thruster was fed by a high-flow iodine feed system and supported by an existing Busek hollow cathode flowing xenon gas. The Phase I propellant feed system was evolved from a previously demonstrated laboratory feed system. Throttling of the thruster between 2 and 11 kW at 200 to 600 V was demonstrated. Testing showed that the efficiency of iodine fueled BHT-8000 is the same as with xenon, with iodine delivering a slightly higher thrust-to-power (T/P) ratio. In Phase II, a complete iodine-fueled system was developed, including the thruster, hollow cathode, and iodine propellant feed system. The nominal power of the Phase II system is 8 kW; however, it can be deeply throttled as well as clustered to much higher power levels. The technology also can be scaled to greater than 100 kW per thruster to support megawatt-class missions. The target thruster efficiency for the full-scale system is 65 percent at high specific impulse (Isp) (approximately 3,000 s) and 60 percent at high thrust (Isp approximately 2,000 s).

Ab initio studies on the photodissociation dynamics of the 1,1-difluoroethyl radical

NASA Astrophysics Data System (ADS)

Fritsche, Lukas; Bach, Andreas; Chen, Peter

2018-02-01

Born-Oppenheimer molecular dynamics trajectory calculations at the HCTH147/6-31G** level of theory simulate the dissociation dynamics of photolytically excited 1,1-difluoroethyl radicals. EOMCCSD/AUG-cc-pVDZ calculations show that an excitation energy of 94.82 kcal/mol is necessary to initiate photodissociation reactions. In contrast to photodissociation dynamics of ethyl radicals where a large discrepancy between actual dissociation rates and rates that are predicted by statistical rate theories, we find reaction rates of 5.1 × 1011 s-1 for the dissociation of an H atom, which is in perfect accord with what is predicted by Rice-Ramsperger-Kassel-Marcus (RRKM) calculations and there is no indication of any nonstatistical effects. However, our trajectory calculations show a much larger fraction of C-C bond breakage reaction of 56% occurring than that expected by RRKM (only 16%).

Ab initio studies on the photodissociation dynamics of the 1,1-difluoroethyl radical.

PubMed

Fritsche, Lukas; Bach, Andreas; Chen, Peter

2018-02-28

Born-Oppenheimer molecular dynamics trajectory calculations at the HCTH147/6-31G** level of theory simulate the dissociation dynamics of photolytically excited 1,1-difluoroethyl radicals. EOMCCSD/AUG-cc-pVDZ calculations show that an excitation energy of 94.82 kcal/mol is necessary to initiate photodissociation reactions. In contrast to photodissociation dynamics of ethyl radicals where a large discrepancy between actual dissociation rates and rates that are predicted by statistical rate theories, we find reaction rates of 5.1 × 10 11 s -1 for the dissociation of an H atom, which is in perfect accord with what is predicted by Rice-Ramsperger-Kassel-Marcus (RRKM) calculations and there is no indication of any nonstatistical effects. However, our trajectory calculations show a much larger fraction of C-C bond breakage reaction of 56% occurring than that expected by RRKM (only 16%).

Combining UV photodissociation action spectroscopy with electron transfer dissociation for structure analysis of gas-phase peptide cation-radicals.

PubMed

Shaffer, Christopher J; Pepin, Robert; Tureček, František

2015-12-01

We report the first example of using ultraviolet (UV) photodissociation action spectroscopy for the investigation of gas-phase peptide cation-radicals produced by electron transfer dissociation. z-Type fragment ions (●) Gly-Gly-Lys(+), coordinated to 18-crown-6-ether (CE), are generated, selected by mass and photodissociated in the 200-400 nm region. The UVPD action spectra indicate the presence of valence-bond isomers differing in the position of the Cα radical defect, (α-Gly)-Gly-Lys(+) (CE), Gly-(α-Gly)-Lys(+) (CE) and Gly-Gly-(α-Lys(+))(CE). The isomers are readily distinguishable by UV absorption spectra obtained by time-dependent density functional theory (TD-DFT) calculations. In contrast, conformational isomers of these radical types are calculated to have similar UV spectra. UV photodissociation action spectroscopy represents a new tool for the investigation of transient intermediates of ion-electron reactions. Specifically, z-type cation radicals are shown to undergo spontaneous hydrogen atom migrations upon electron transfer dissociation. Copyright © 2015 John Wiley & Sons, Ltd.

Breast-Milk Iodine Concentrations and Iodine Levels of Infants According to the Iodine Status of the Country of Residence: A Systematic Review and Meta-Analysis.

PubMed

Nazeri, Pantea; Kabir, Ali; Dalili, Hosein; Mirmiran, Parvin; Azizi, Fereidoun

2018-01-01

Iodine, an essential micronutrient, plays a critical role in normal growth and development, especially during the first two years of life. This systematic review and meta-analysis is among the first to evaluate breast-milk iodine concentrations and infant iodine status in countries characterized by iodine sufficiency or deficiency. PubMed, Web of Science, Cochrane Library, Google Scholar, and other relevant databases, as well as reference lists of previous reviews, were searched for relevant studies published between 1986 and 2016. Mean or median breast-milk and infant urinary iodine concentrations, along with other relevant data, were extracted from eligible studies. Each study was assessed for quality and risk of bias. Of the 496 identified studies, 57 met the criteria for inclusion in the meta-analysis. The mean (confidence interval [CI]) iodine concentrations in maternal colostrum were 152.0 μg/L [CI 106.2-198.7 μg/L] and 57.8 μg/L [CI 41.4-74.1 μg/L] in iodine-sufficient and -deficient countries, respectively, indicating a significant difference between the two iodine statuses. By contrast, the corresponding values in mature milk did not differ significantly between mothers in iodine-sufficient and -deficient countries (71.5 μg/L [CI 51.0-92.0 μg/L] and 28.0 μg/L [CI -13.8 to 69.9 μg/L], respectively]. The weighted urinary iodine levels [CIs] of breast-fed infants in iodine-sufficient countries were significantly higher than those in iodine-deficient countries (164.5 μg/L [CI 116.4-212.7 μg/L] vs. 70.4 μg/L [CI 46.2-94.6 μg/L]). Similarly, a significant difference was observed in the pooled estimates of urinary iodine levels [CIs] among formula-fed infants in iodine-sufficient versus iodine-deficient countries (310.3 μg/L [CI 287.4-342.1 μg/L] vs. 38.3 μg/L [CI 23.4-53.2 μg/L]). The meta-analysis reveals that in iodine-sufficient countries, the mean iodine concentrations in colostrum and mature breast milk

Laser-induced fluorescence detection strategies for sodium atoms and compounds in high-pressure combustors

NASA Technical Reports Server (NTRS)

Weiland, Karen J. R.; Wise, Michael L.; Smith, Gregory P.

1993-01-01

A variety of laser-induced fluorescence schemes were examined experimentally in atmospheric pressure flames to determine their use for sodium atom and salt detection in high-pressure, optically thick environments. Collisional energy transfer plays a large role in fluorescence detection. Optimum sensitivity, at the parts in 10 exp 9 level for a single laser pulse, was obtained with the excitation of the 4p-3s transition at 330 nm and the detection of the 3d-3p fluorescence at 818 nm. Fluorescence loss processes, such as ionization and amplified spontaneous emission, were examined. A new laser-induced atomization/laser-induced fluorescence detection technique was demonstrated for NaOH and NaCl. A 248-nm excimer laser photodissociates the salt molecules present in the seeded flames prior to atom detection by laser-induced fluorescence.

FDA regulations regarding iodine addition to foods and labeling of foods containing added iodine12

PubMed Central

Trumbo, Paula R

2016-01-01

The US Food and Drug Administration (FDA) regulates the addition of iodine to infant formulas, the iodization of salt, and the addition of salt and iodine to foods. The required amount of iodine in infant formulas is based on caloric content, and the label must provide the iodine content per 100 kcal. Cuprous iodide and potassium iodide may be added to table salt as a source of dietary iodine at a maximum amount of 0.01%; if added, the label must indicate that the salt is iodized. Table salt to which iodine has not been added must bear the statement, “This salt does not supply iodide, a necessary nutrient.” If a nutrient is to be appropriately added to a food for the purpose of correcting a dietary insufficiency, there should be sufficient scientific information available to demonstrate a nutritional deficiency and/or identify a public health problem. Furthermore, the population groups that would benefit from the proposed fortification should be identified. If iodine is added to a food, the percent Daily Value of iodine must be listed. There are no FDA regulations governing ingredient standards for dietary supplements. As a result, some dietary supplements include iodine and others do not. If a supplement contains iodine, the Supplement Facts label must list iodine as a nutrient ingredient. If iodine is not listed on the Supplement Facts label, then it has not been added. There are similarities between the FDA, which establishes US food regulations and policies, and the Codex Alimentarius (Codex), which develops international food standards and guidelines under the aegis of the FAO and the WHO. Both the FDA and Codex call for the labeling of table salt to indicate fortification with iodine, voluntary labeling of iodine on foods, and a Daily Value (called a Nutrient Reference Value by Codex) of 150 μg for iodine. PMID:27534626

High-Performance Water-Iodinating Cartridge

NASA Technical Reports Server (NTRS)

Sauer, Richard; Gibbons, Randall E.; Flanagan, David T.

1993-01-01

High-performance cartridge contains bed of crystalline iodine iodinates water to near saturation in single pass. Cartridge includes stainless-steel housing equipped with inlet and outlet for water. Bed of iodine crystals divided into layers by polytetrafluoroethylene baffles. Holes made in baffles and positioned to maximize length of flow path through layers of iodine crystals. Resulting concentration of iodine biocidal; suppresses growth of microbes in stored water or disinfects contaminated equipment. Cartridge resists corrosion and can be stored wet. Reused several times before necessary to refill with fresh iodine crystals.

Analytic H I-to-H2 Photodissociation Transition Profiles

NASA Astrophysics Data System (ADS)

Bialy, Shmuel; Sternberg, Amiel

2016-05-01

We present a simple analytic procedure for generating atomic (H I) to molecular ({{{H}}}2) density profiles for optically thick hydrogen gas clouds illuminated by far-ultraviolet radiation fields. Our procedure is based on the analytic theory for the structure of one-dimensional H I/{{{H}}}2 photon-dominated regions, presented by Sternberg et al. Depth-dependent atomic and molecular density fractions may be computed for arbitrary gas density, far-ultraviolet field intensity, and the metallicity-dependent H2 formation rate coefficient, and dust absorption cross section in the Lyman-Werner photodissociation band. We use our procedure to generate a set of {{H}} {{I}}{-}{to}{-}{{{H}}}2 transition profiles for a wide range of conditions, from the weak- to strong-field limits, and from super-solar down to low metallicities. We show that if presented as functions of dust optical depth, the {{H}} {{I}} and {{{H}}}2 density profiles depend primarily on the Sternberg “α G parameter” (dimensionless) that determines the dust optical depth associated with the total photodissociated {{H}} {{I}} column. We derive a universal analytic formula for the {{H}} {{I}}{-}{to}{-}{{{H}}}2 transition points as a function of just α G. Our formula will be useful for interpreting emission-line observations of H I/{{{H}}}2 interfaces, for estimating star formation thresholds, and for sub-grid components in hydrodynamics simulations.

New ab initio potential surfaces and three-dimensional quantum dynamics for transition state spectroscopy in ozone photodissociation

NASA Astrophysics Data System (ADS)

Yamashita, Koichi; Morokuma, Keiji; Le Quéré, Frederic; Leforestier, Claude

1992-04-01

New ab initio potential energy surfaces (PESs) of the ground and B ( 1B 2) states of ozone have been calculated with the CASSCF-SECI/DZP method to describe the three-dimensional photodissociation process. The dissociation energy of the ground state and the vertical barrier height of the B PES are obtained to be 0.88 and 1.34 eV, respectively, in better agreement with the experimental values than the previous calculation. The photodissociation autocorrelation function, calculated on the new B PES, based on exact three-dimensional quantum dynamics, reproduces well the main recurrence feature extracted from the experimental spectra.

Iodine-induced hyperthyroidism--an epidemiological survey several years after institution of iodine prophylaxis in Poland.

PubMed

Lewiński, A; Szybiński, Z; Bandurska-Stankiewicz, E; Grzywa, M; Karwowska, A; Kinalska, I; Kowalska, A; Makarewicz, J; Nauman, J; Słowińska-Klencka, D; Sowiński, J; Syrenicz, A; Zonenberg, A; Huszno, B; Klencki, M

2003-01-01

In 1997, the obligatory model of iodine prophylaxis was introduced in Poland in order to correct the existing status of mild and/or moderate iodine deficiency. In order to monitor possible side-effects of increased iodine supply, studies on iodine-induced hyperthyroidism were initiated by establishing several regional registers of hyperthyroidism. In the present paper, the results of a two-year monitoring (2000-2001) have been summarized. There are no epidemiological data on hyperthyroidism prior to starting the iodine prophylaxis, but the obtained current data are comparable to observations in other countries, made after iodine supplementation. The incidence of iodine-induced hyperthyroidism did not exceed the acceptable level, thus confirming--together with previous observations on the effectiveness of iodine prophylaxis--the adequacy of applied dose of KI (30 microg/kg NaCl), used for salt iodization in Poland.

Theoretical studies of solar lasers and converters

NASA Technical Reports Server (NTRS)

Heinbockel, John H.

1990-01-01

The research described consisted of developing and refining the continuous flow laser model program including the creation of a working model. The mathematical development of a two pass amplifier for an iodine laser is summarized. A computer program for the amplifier's simulation is included with output from the simulation model.

A rechargeable iodine-carbon battery that exploits ion intercalation and iodine redox chemistry.

PubMed

Lu, Ke; Hu, Ziyu; Ma, Jizhen; Ma, Houyi; Dai, Liming; Zhang, Jintao

2017-09-13

Graphitic carbons have been used as conductive supports for developing rechargeable batteries. However, the classic ion intercalation in graphitic carbon has yet to be coupled with extrinsic redox reactions to develop rechargeable batteries. Herein, we demonstrate the preparation of a free-standing, flexible nitrogen and phosphorus co-doped hierarchically porous graphitic carbon for iodine loading by pyrolysis of polyaniline coated cellulose wiper. We find that heteroatoms could provide additional defect sites for encapsulating iodine while the porous carbon skeleton facilitates redox reactions of iodine and ion intercalation. The combination of ion intercalation with redox reactions of iodine allows for developing rechargeable iodine-carbon batteries free from the unsafe lithium/sodium metals, and hence eliminates the long-standing safety issue. The unique architecture of the hierarchically porous graphitic carbon with heteroatom doping not only provides suitable spaces for both iodine encapsulation and cation intercalation but also generates efficient electronic and ionic transport pathways, thus leading to enhanced performance.Carbon-based electrodes able to intercalate Li + and Na + ions have been exploited for high performing energy storage devices. Here, the authors combine the ion intercalation properties of porous graphitic carbons with the redox chemistry of iodine to produce iodine-carbon batteries with high reversible capacities.

Effects of iodine deficiency in pregnancy.

PubMed

Pearce, Elizabeth N

2012-06-01

Dietary iodine requirements are increased in pregnancy due to increased thyroid hormone production, increased renal iodine losses, and fetal iodine requirements. Adverse effects of iodine deficiency in pregnancy include maternal and fetal goiter, cretinism, intellectual impairments, neonatal hypothyroidism, and increased pregnancy loss and infant. Dietary iodine requirements remain increased in lactation due to the concentration of iodine in breast milk. Iodine deficiency remains a significant global public health problem. Excess iodine ingestion in pregnancy, while a relatively uncommon problem, may also have adverse fetal effects. However, the safe upper limit for chronic iodine ingestion in pregnancy and lactation is not currently well defined. Copyright © 2012 Elsevier GmbH. All rights reserved.

Feasibility of Iodine and Bromine analysis in Genesis AloS collectors

NASA Astrophysics Data System (ADS)

Pravdivtseva, O.; Meshik, A.; Hohenberg, C. M.; Burnett, D. S.

2011-12-01

Comparison of solar, meteoritic and terrestrial elemental abundances provides understanding of the formation and evolution of the solar system. Yet, the majority of the solar abundances are based on meteoritic values [1-6]. As a continuation of our noble gas measurements of the Solar Wind (SW) [7] we attempted to evaluate the possibility of SW-iodine and SW-bromine analyses in the Genesis Solar Wind Aluminum on Sapphire collectors (AloS) using the conversions: 127I(n,γβ)128Xe, 79Br(n,γβ)80Kr and 81Br(n,γβ)82Kr. To estimate the extent of terrestrial halogen contamination in Genesis collectors, several flown fragments of AloS were submerged in methanol (for 1 hour and for 48 hours), rinsed, dried, sealed under vacuum in fused quartz ampoules and irradiated at the Missouri University Research Reactor receiving fluence ˜ 2E+19 thermal neutrons/cm2. Single step laser extraction using 1064 nm laser ablation of 0.7 cm2 area demonstrated clear signature of solar wind as indicated by 129Xe/132Xe = 1.045 ± 0.005, while 128Xe/132Xe = 1.01 ± 0.03 had a 12-fold excess compared to the solar value. Longer washing apparently reduces iodine contamination 4 times, implying that it is surface correlated. Krypton analysis showed 17% excess in 82Kr and 3-fold excess in 80Kr in agreement with their production ratio. A longer 48-hour washing reduced Br contamination 50 times. In order to better separate SW halogens from ubiquitous terrestrial contamination we employed a depth-profiling of AloS using 266 nm laser ablation. Laser beam power was increased in 12 consecutive steps using a combination of controlled defocusing and attenuation by a polarizing beamsplitter. Depth profile analysis revealed that terrestrial halogen contamination is present at the surface and at the interface between Al and sapphire substrate and is more pronounced for iodine, as indicated by 128Xe/132Xe ratio that is higher than atmospheric and solar wind values in all 12 rasters. While washing procedure

Electronic and vibrational spectroscopy and vibrationally mediated photodissociation of V+(OCO).

PubMed

Citir, Murat; Altinay, Gokhan; Metz, Ricardo B

2006-04-20

Electronic spectra of gas-phase V+(OCO) are measured in the near-infrared from 6050 to 7420 cm(-1) and in the visible from 15,500 to 16,560 cm(-1), using photofragment spectroscopy. The near-IR band is complex, with a 107 cm(-1) progression in the metal-ligand stretch. The visible band shows clearly resolved vibrational progressions in the metal-ligand stretch and rock, and in the OCO bend, as observed by Brucat and co-workers. A vibrational hot band gives the metal-ligand stretch frequency in the ground electronic state nu3'' = 210 cm(-1). The OCO antisymmetric stretch frequency in the ground electronic state (nu1'') is measured by using vibrationally mediated photodissociation. An IR laser vibrationally excites ions to nu1'' = 1. Vibrationally excited ions selectively dissociate following absorption of a second, visible photon at the nu1' = 1 <-- nu1'' = 1 transition. Rotational structure in the resulting vibrational action spectrum confirms that V+(OCO) is linear and gives nu1'' = 2392.0 cm(-1). The OCO antisymmetric stretch frequency in the excited electronic state is nu1' = 2368 cm(-1). Both show a blue shift from the value in free CO2, due to interaction with the metal. Larger blue shifts observed for complexes with fewer ligands agree with trends seen for larger V+(OCO)n clusters.

Nonadiabatic effects in C-Br bond scission in the photodissociation of bromoacetyl chloride

NASA Astrophysics Data System (ADS)

Valero, Rosendo; Truhlar, Donald G.

2006-11-01

Bromoacetyl chloride photodissociation has been interpreted as a paradigmatic example of a process in which nonadiabatic effects play a major role. In molecular beam experiments by Butler and co-workers [J. Chem. Phys. 95, 3848 (1991); J. Chem. Phys. 97, 355 (1992)], BrCH2C(O )Cl was prepared in its ground electronic state (S0) and excited with a laser at 248nm to its first excited singlet state (S1). The two main ensuing photoreactions are the ruptures of the C-Cl bond and of the C-Br bond. A nonadiabatic model was proposed in which the C-Br scission is strongly suppressed due to nonadiabatic recrossing at the barrier formed by the avoided crossing between the S1 and S2 states. Recent reduced-dimensional dynamical studies lend support to this model. However, another interpretation that has been given for the experimental results is that the reduced probability of C-Br scission is a consequence of incomplete intramolecular energy redistribution. To provide further insight into this problem, we have studied the energetically lowest six singlet electronic states of bromoacetyl chloride by using an ab initio multiconfigurational perturbative electronic structure method. Stationary points (minima and saddle points) and minimum energy paths have been characterized on the S0 and S1 potential energy surfaces. The fourfold way diabatization method has been applied to transform five adiabatic excited electronic states to a diabatic representation. The diabatic potential energy matrix of the first five excited singlet states has been constructed along several cuts of the potential energy hypersurfaces. The thermochemistry of the photodissociation reactions and a comparison with experimental translational energy distributions strongly suggest that nonadiabatic effects dominate the C-Br scission, but that the reaction proceeds along the energetically allowed diabatic pathway to excited-state products instead of being nonadiabatically suppressed. This conclusion is also

Photodissociation of OCS: deviations between theory and experiment, and the importance of higher order correlation effects.

PubMed

Schmidt, J A; Olsen, J M H

2014-11-14

The photodissociation of carbonyl sulfide (OCS) was investigated theoretically in a series of studies by Schmidt and co-workers. Initial studies [J. A. Schmidt, M. S. Johnson, G. C. McBane, and R. Schinke, J. Chem. Phys. 136, 131101 (2012); J. A. Schmidt, M. S. Johnson, G. C. McBane, and R. Schinke, J. Chem. Phys. 137, 054313 (2012)] found photodissociation in the first UV-band to occur mainly by excitation of the 2(1)A' (A) excited state. However, in a later study [G. C. McBane, J. A. Schmidt, M. S. Johnson, and R. Schinke, J. Chem. Phys. 138, 094314 (2013)] it was found that a significant fraction of photodissociation must occur by excitation of 1(1)A″ (B) excited state to explain the product angular distribution. The branching between excitation of the A and B excited states is determined by the magnitude of the transition dipole moment vectors in the Franck-Condon region. This study examines the sensitivity of these quantities to changes in the employed electronic structure methodology. This study benchmarks the methodology employed in previous studies against highly correlated electronic structure methods (CC3 and MRAQCC) and provide evidence in support of the picture of the OCS photodissociation process presented in [G. C. McBane, J. A. Schmidt, M. S. Johnson, and R. Schinke, J. Chem. Phys. 138, 094314 (2013)] showing that excitation of A and B electronic states both contribute significantly to the first UV absorption band of OCS. In addition, this study presents evidence in support of the assertion that the A state potential energy surface employed in previous studies underestimates the energy at highly bent geometries (γ ∼ 70°) leading to overestimated rotational energy in the product CO.

High prevalence of iodine deficiency in pregnant women living in adequate iodine area

PubMed Central

Mioto, Verônica Carneiro Borges; Monteiro, Ana Carolina de Castro Nassif Gomes; de Camargo, Rosalinda Yossie Asato; Borel, Andréia Rodrigues; Catarino, Regina Maria; Kobayashi, Sergio; Chammas, Maria Cristina; Marui, Suemi

2018-01-01

Objectives Iodine deficiency during pregnancy is associated with obstetric and neonatal adverse outcomes. Serum thyroglobulin (sTg) and thyroid volume (TV) are optional tools to urinary iodine concentration (UIC) for defining iodine status. This cross-sectional study aims to evaluate the iodine status of pregnant women living in iodine-adequate area by spot UIC and correlation with sTg, TV and thyroid function. Methods Two hundred and seventy-three pregnant women were evaluated at three trimesters. All had no previous thyroid disease, no iodine supplementation and negative thyroperoxidase and thyroglobulin antibodies. Thyroid function and sTg were measured using electrochemiluminescence immunoassays. TV was determined by ultrasonography; UIC was determined using a modified Sandell–Kolthoff method. Results Median UIC was 146 µg/L, being 52% iodine deficient and only 4% excessive. TSH values were 1.50 ± 0.92, 1.50 ± 0.92 and 1.91 ± 0.96 mIU/L, respectively, in each trimester (P = 0.001). sTg did not change significantly during trimesters with median 11.2 ng/mL and only 3.3% had above 40 ng/mL. Mean TV was 9.3 ± 3.4 mL, which positively correlated with body mass index, but not with sTg. Only 4.5% presented with goitre. When pregnant women were categorized as iodine deficient (UIC < 150 µg/L), adequate (≥150 and <250 µg/L) and excessive (≥250 µg/L), sTg, thyroid hormones and TV at each trimester showed no statistical differences. Conclusions Iodine deficiency was detected frequently in pregnant women living in iodine-adequate area. sTg concentration and TV did not correlate to UIC. Our observation also demonstrated that the Brazilian salt-iodization programme prevents deficiency, but does not maintain iodine status within adequate and recommended ranges for pregnant women. PMID:29700098

High prevalence of iodine deficiency in pregnant women living in adequate iodine area.

PubMed

Mioto, Verônica Carneiro Borges; Monteiro, Ana Carolina de Castro Nassif Gomes; de Camargo, Rosalinda Yossie Asato; Borel, Andréia Rodrigues; Catarino, Regina Maria; Kobayashi, Sergio; Chammas, Maria Cristina; Marui, Suemi

2018-05-01

Iodine deficiency during pregnancy is associated with obstetric and neonatal adverse outcomes. Serum thyroglobulin (sTg) and thyroid volume (TV) are optional tools to urinary iodine concentration (UIC) for defining iodine status. This cross-sectional study aims to evaluate the iodine status of pregnant women living in iodine-adequate area by spot UIC and correlation with sTg, TV and thyroid function. Two hundred and seventy-three pregnant women were evaluated at three trimesters. All had no previous thyroid disease, no iodine supplementation and negative thyroperoxidase and thyroglobulin antibodies. Thyroid function and sTg were measured using electrochemiluminescence immunoassays. TV was determined by ultrasonography; UIC was determined using a modified Sandell-Kolthoff method. Median UIC was 146 µg/L, being 52% iodine deficient and only 4% excessive. TSH values were 1.50 ± 0.92, 1.50 ± 0.92 and 1.91 ± 0.96 mIU/L, respectively, in each trimester ( P  = 0.001). sTg did not change significantly during trimesters with median 11.2 ng/mL and only 3.3% had above 40 ng/mL. Mean TV was 9.3 ± 3.4 mL, which positively correlated with body mass index, but not with sTg. Only 4.5% presented with goitre.When pregnant women were categorized as iodine deficient (UIC < 150 µg/L), adequate (≥150 and <250 µg/L) and excessive (≥250 µg/L), sTg, thyroid hormones and TV at each trimester showed no statistical differences. Iodine deficiency was detected frequently in pregnant women living in iodine-adequate area. sTg concentration and TV did not correlate to UIC. Our observation also demonstrated that the Brazilian salt-iodization programme prevents deficiency, but does not maintain iodine status within adequate and recommended ranges for pregnant women. © 2018 The authors.

Thermally assisted infrared multiphoton photodissociation in a quadrupole ion trap.

PubMed

Payne, A H; Glish, G L

2001-08-01

Thermally assisted infrared multiphoton photodissociation (TA-IRMPD) provides an effective means to dissociate ions in the quadrupole ion trap mass spectrometer (QITMS) without detrimentally affecting the performance of the instrument. IRMPD can offer advantages over collision-induced dissociation (CID). However, collisions with the QITMS bath gas at the standard pressure and ambient temperature cause IR-irradiated ions to lose energy faster than photons can be absorbed to induce dissociation. The low pressure required for IRMPD (< or = 10(-5) Torr) is not that required for optimal performance of the QITMS (10(-3) Torr), and sensitivity and resolution suffer. TA-IRMPD is performed with the bath gas at an elevated temperature. The higher temperature of the bath gas results in less energy lost in collisions of the IR-excited ions with the bath gas. Thermal assistance allows IRMPD to be used at or near optimal pressures, which results in an approximately 1 order of magnitude increase in signal intensity. Unlike CID, IRMPD allows small product ions, those less than about one-third the m/z of the parent ion, to be observed. IRMPD should also be more easily paired with fluctuating ion sources, as the corresponding fluctuations in resonant frequencies do not affect IRMPD. Finally, while IR irradiation nonselectively causes dissociation of all ions, TA-IRMPD can be made selective by using axial expansion to move ions away from the path of the laser beam.

Photodissociation of the CH3O and CH3S radical molecules: An ab initio electronic structure study

PubMed Central

Bouallagui, A.; Zanchet, A.; Yazidi, O.; Jaïdane, N.; Bañares, L.; Senent, M.L.; García-Vela, A.

2018-01-01

The electronic states and the spin-orbit couplings between them involved in the photodissociation process of the radical molecules CH3X, CH3X → CH3 + X(X = O, S), taking place after the Ā(2A1) ← X̄(2E) transition, have been investigated using highly correlated ab initio techniques. A two-dimensional representation of both the potential-energy surfaces (PESs) and the couplings is generated. This description includes the C-X dissociative mode and the CH3 umbrella mode. Spin-orbit effects are found to play a relevant role on the shape of the excited state potential-energy surfaces, particularly in the CH3S case where the spin-orbit couplings are more than twice more intense than in CH3O. The potential surfaces and couplings reported here for the present set of electronic states allow for the first complete description of the above photodissociation process. The different photodissociation mechanisms are analyzed and discussed in the light of the results obtained. PMID:29143005

Current global iodine status and progress over the last decade towards the elimination of iodine deficiency.

PubMed Central

Andersson, Maria; Takkouche, Bahi; Egli, Ines; Allen, Henrietta E.; de Benoist, Bruno

2005-01-01

OBJECTIVE: To estimate worldwide iodine nutrition and monitor country progress towards sustained elimination of iodine deficiency disorders. METHODS: Cross-sectional data on urinary iodine (UI) and total goitre prevalence (TGP) in school-age children from 1993-2003 compiled in the WHO Global Database on Iodine Deficiency were analysed. The median UI was used to classify countries according to the public health significance of their iodine nutrition status. Estimates of the global and regional populations with insufficient iodine intake were based on the proportion of each country's population with UI below 100 microg/l. TGP was computed for trend analysis over 10 years. FINDINGS: UI data were available for 92.1% of the world's school-age children. Iodine deficiency is still a public health problem in 54 countries. A total of 36.5% (285 million) school-age children were estimated to have an insufficient iodine intake, ranging from 10.1% in the WHO Region of the Americas to 59.9% in the European Region. Extrapolating this prevalence to the general population generated an estimate of nearly two billion individuals with insufficient iodine intake. Iodine intake was more than adequate, or excessive, in 29 countries. Global TGP in the general population was 15.8%. CONCLUSION: Forty-three countries have reached optimal iodine nutrition. Strengthened UI monitoring is required to ensure that salt iodization is having the desired impact, to identify at-risk populations and to ensure sustainable prevention and control of iodine deficiency. Efforts to eliminate iodine deficiency should be maintained and expanded. PMID:16175826

Determination of iodide, iodate and organo-iodine in waters with a new total organic iodine measurement approach.

PubMed

Gong, Tingting; Zhang, Xiangru

2013-11-01

The dissolved iodine species that dominate aquatic systems are iodide, iodate and organo-iodine. These species may undergo transformation to one another and thus affect the formation of iodinated disinfection byproducts during disinfection of drinking waters or wastewater effluents. In this study, a fast, sensitive and accurate method for determining these iodine species in waters was developed by derivatizing iodide and iodate to organic iodine and measuring organic iodine with a total organic iodine (TOI) measurement approach. Within this method, organo-iodine was determined directly by TOI measurement; iodide was oxidized by monochloramine to hypoiodous acid and then hypoiodous acid reacted with phenol to form organic iodine, which was determined by TOI measurement; iodate was reduced by ascorbic acid to iodide and then determined as iodide. The quantitation limit of organo-iodine or sum of organo-iodine and iodide or sum of organo-iodine, iodide and iodate was 5 μg/L as I for a 40 mL water sample (or 2.5 μg/L as I for an 80 mL water sample, or 1.25 μg/L as I for a 160 mL water sample). This method was successfully applied to the determination of iodide, iodate and organo-iodine in a variety of water samples, including tap water, seawater, urine and wastewater. The recoveries of iodide, iodate and organo-iodine were 91-109%, 90-108% and 91-108%, respectively. The concentrations and distributions of iodine species in different water samples were obtained and compared. Copyright © 2013 Elsevier Ltd. All rights reserved.

Production of reactive species using vacuum ultraviolet photodissociation as a tool for studying their effects in plasma medicine: simulations and measurements

NASA Astrophysics Data System (ADS)

Ono, Ryo; Tokumitsu, Yusuke; Zen, Shungo; Yonemori, Seiya

2014-11-01

We propose a method for producing OH, H, O, O3, and O2(a1Δg) using the vacuum ultraviolet photodissociation of H2O and O2 as a tool for studying the reaction processes of plasma medicine. For photodissociation, an H2O/He or O2/He mixture flowing in a quartz tube is irradiated by a Xe2 or Kr2 excimer lamp. The effluent can be applied to a target. Simulations show that the Xe2 lamp method can produce OH radicals within 0.1-1 ppm in the effluent at 5 mm from a quartz tube nozzle. This is comparable to those produced by a helium atmospheric-pressure plasma jet (He-APPJ) currently used in plasma medicine. The Xe2 lamp method also produces H atoms of, at most, 6 ppm. In contrast, the maximum O densities produced by the Xe2 and Kr2 lamp methods are 0.15 ppm and 2.5 ppm, respectively; these are much lower than those from He-APPJ (several tens of ppm). Both lamp methods can produce ozone at concentrations above 1000 ppm and O2(a1Δg) at tens of ppm. The validity of the simulations is verified by measuring the O3 and OH densities produced by the Xe2 lamp method using ultraviolet absorption and laser-induced fluorescence. The differences between the measured and simulated densities for O3 and OH are 20% and factors of 3-4, respectively.

Research on fluorescence from photoionization, photodissociation, and vacuum, along with bending quantrum study

NASA Technical Reports Server (NTRS)

Judge, D. L.

1975-01-01

Reports of research concerning the fluorescence of CS2 are presented. Fluorescence from fragments of CS2 vapor produced by vacuum ultraviolet radiation, and fluorescence from photoionization of CS2 vapor are discussed along with fluorescence produced by photodissociation of CS2, and fluorescence from photoionization of OCS.

Mixed-layered bismuth-oxygen-iodine materials for capture and waste disposal of radioactive iodine

DOEpatents

Krumhansl, James L; Nenoff, Tina M

2013-02-26

Materials and methods of synthesizing mixed-layered bismuth oxy-iodine materials, which can be synthesized in the presence of aqueous radioactive iodine species found in caustic solutions (e.g. NaOH or KOH). This technology provides a one-step process for both iodine sequestration and storage from nuclear fuel cycles. It results in materials that will be durable for repository conditions much like those found in Waste Isolation Pilot Plant (WIPP) and estimated for Yucca Mountain (YMP). By controlled reactant concentrations, optimized compositions of these mixed-layered bismuth oxy-iodine inorganic materials are produced that have both a high iodine weight percentage and a low solubility in groundwater environments.

Importance of iodine in pregnancy.

PubMed

Carreto-Molina, Nicolás; García-Solís, Pablo; Solís-S, Juan Carlos; Robles-Osorio, Ludivina; Hernández-Montiel, Hebert Luis; Vega-Malagón, Genaro

2012-09-01

Iodine is an essential constituent of thyroid hormones (TH). TH actively take part in critical periods of brain development during embryonic, fetal and postnatal stages. Therefore the absence of TH or iodine in these critical periods produces an irreversible brain damage. In fact, it is known that iodine deficiency is the leading cause of preventable brain damage worldwide. Because of the physiological adjustments during pregnancy iodine requirements increase significantly from 150 microg per day in non-pregnant adult women to 250 microg per day. Moreover, recent epidemiological studies around the world show that iodine intake during pregnancy is insufficient in many countries, even in developed countries like Australia, Spain and Italy. In the present work an overview of the importance of iodine nutrition during pregnancy is given.

Iodine Intakes of Victorian Schoolchildren Measured Using 24-h Urinary Iodine Excretion

PubMed Central

Beckford, Kelsey; Margerison, Claire; Skeaff, Sheila A.

2017-01-01

Mandatory fortification of bread with iodized salt was introduced in Australia in 2009, and studies using spot urine collections conducted post fortification indicate that Australian schoolchildren are now replete. However an accurate estimate of daily iodine intake utilizing 24-h urinary iodine excretion (UIE μg/day) has not been reported and compared to the estimated average requirement (EAR). This study aimed to assess daily total iodine intake and status of a sample of primary schoolchildren using 24-h urine samples. Victorian primary school children provided 24-h urine samples between 2011 and 2013, from which urinary iodine concentration (UIC, μg/L) and total iodine excretion (UIE, μg/day) as an estimate of intake was determined. Valid 24-h urine samples were provided by 650 children, mean (SD) age 9.3 (1.8) years (n = 359 boys). The mean UIE of 4–8 and 9–13 year olds was 94 (48) and 111 (57) μg/24-h, respectively, with 29% and 26% having a UIE below the age-specific EAR. The median (IQR) UIC was 124 (83,172) μg/L, with 36% of participants having a UIC < 100 μg/L. This convenience sample of Victorian schoolchildren were found to be iodine replete, based on UIC and estimated iodine intakes derived from 24-h urine collections, confirming the findings of the Australian Health Survey. PMID:28867787

Iodine Satellite

NASA Technical Reports Server (NTRS)

Kamhawi, Hani; Dankanich, John; Martinez, Andres; Petro, Andrew

2015-01-01

The Iodine Satellite (iSat) spacecraft will be the first CubeSat to demonstrate high change in velocity from a primary propulsion system by using Hall thruster technology and iodine as a propellant. The mission will demonstrate CubeSat maneuverability, including plane change, altitude change and change in its closest approach to Earth to ensure atmospheric reentry in less than 90 days. The mission is planned for launch in fall 2017. Hall thruster technology is a type of electric propulsion. Electric propulsion uses electricity, typically from solar panels, to accelerate the propellant. Electric propulsion can accelerate propellant to 10 times higher velocities than traditional chemical propulsion systems, which significantly increases fuel efficiency. To enable the success of the propulsion subsystem, iSat will also demonstrate power management and thermal control capabilities well beyond the current state-of-the-art for spacecraft of its size. This technology is a viable primary propulsion system that can be used on small satellites ranging from about 22 pounds (10 kilograms) to more than 1,000 pounds (450 kilograms). iSat's fuel efficiency is ten times greater and its propulsion per volume is 100 times greater than current cold-gas systems and three times better than the same system operating on xenon. iSat's iodine propulsion system consists of a 200 watt (W) Hall thruster, a cathode, a tank to store solid iodine, a power processing unit (PPU) and the feed system to supply the iodine. This propulsion system is based on a 200 W Hall thruster developed by Busek Co. Inc., which was previously flown using xenon as the propellant. Several improvements have been made to the original system to include a compact PPU, targeting greater than 80 percent reduction in mass and volume of conventional PPU designs. The cathode technology is planned to enable heaterless cathode conditioning, significantly increasing total system efficiency. The feed system has been designed to

On the ultraviolet photodissociation of H2Te

NASA Astrophysics Data System (ADS)

Alekseyev, Aleksey B.; Liebermann, Heinz-Peter; Wittig, Curt

2004-11-01

The photodissociation of H2Te through excitation in the first absorption band is investigated by means of multireference spin-orbit configuration interaction (CI) calculations. Bending potentials for low-lying electronic states of H2Te are obtained in C2v symmetry for Te-H distances fixed at the ground state equilibrium value of 3.14a0, as well as for the minimum energy path constrained to R1=R2. Asymmetric cuts of potential energy surfaces for excited states (at R1=3.14a0 and θ=90.3°) are obtained for the first time. It is shown that vibrational structure in the 380-400 nm region of the long wavelength absorption tail is due to transitions to 3A', which has a shallow minimum at large HTe-H separations. Transitions to this state are polarized in the molecular plane, and this state converges to the excited TeH(2Π1/2)+H(2S) limit. These theoretical data are in accord with the selectivity toward TeH(2Π1/2) relative to TeH(2Π3/2) that has been found experimentally for 355 nm H2Te photodissociation. The calculated 3A'←X˜A' transition dipole moment increases rapidly with HTe-H distance; this explains the observation of 3A' vibrational structure for low vibrational levels, despite unfavorable Franck-Condon factors. According to the calculated vertical energies and transition moment data, the maximum in the first absorption band at ≈245 nm is caused by excitation to 4A″, which has predominantly 21A″ (1B1 in C2v symmetry) character.

Long-term migration of iodine in sedimentary rocks based on iodine speciation and 129I/127I ratio

NASA Astrophysics Data System (ADS)

Togo, Y.; Takahashi, Y.; Amano, Y.; Matsuzaki, H.; Suzuki, Y.; Muramatsu, Y.; Iwatsuki, T.

2012-12-01

[Introduction] 129I is one of the available indexes of long-term migration of groundwater solutes, because of its long half-life (15.7 million years) and low sorption characteristics. The Horonobe underground research center (Japan Atomic Energy Agency), at which are conducted research and development of fundamental techniques on geological disposal of high-level radioactive waste, is an appropriate site for natural analogue studies, because iodine concentration in groundwater is high in this area. To predict iodine behavior in natural systems, speciation of iodine is essential because of different mobility among each species. In this study, we determined iodine speciation and129I/127I isotope ratios of rock and groundwater samples to investigate long term migration of iodine. [Methods] All rock and groundwater samples were collected at Horonobe underground research center. The region is underlain mainly by Neogene to Quaternary marine sedimentary rocks, the Wakkanai Formation (Wk Fm, siliceous mudstones), and the overlying Koetoi Formation (Kt Fm, diatomaceous mudstones). Iodine species in rock samples were determined by iodine K-edge X-ray absorption near edge structure (SPring-8 BL01B1). Thin sections of rock samples were prepared, and iodine mapping were obtained by micro-XRF analysis (SPring-8 BL37XU). Iodine species (IO3-, I-, and organic I) in groundwater were separately detected by high performance liquid chromatography connected to ICP-MS. The 129I/127I ratios in groundwater and rock samples were measured by accelerator mass spectrometry (MALT, Univ. of Tokyo). Iodine in rock samples were separated by pyrohydrolysis and water extraction. [Results and discussion] Concentration of iodine in groundwater varied widely and was much higher than that of seawater showing a high correlation with that of chlorine (R2 = 0.90). Species of iodine in groundwater was mainly I-. Iodine in rock samples decreased near the boundary between Wk and Kt Fms. Iodine K-edge XANES

Assessing iodine intake, iodine status, and the effects of maternal iodine supplementation: introduction to articles arising from 3 workshops held by the NIH Office of Dietary Supplements.

PubMed

Ershow, Abby G; Goodman, Gay; Coates, Paul M; Swanson, Christine A

2016-09-01

The NIH Office of Dietary Supplements (ODS) convened 3 workshops on iodine nutrition in 2014, each held in Rockville, Maryland. These workshops were part of the ongoing ODS Iodine Initiative, begun in 2011 in response to concerns that US pregnant women may be at risk of iodine deficiency and that a high fraction of prenatal dietary supplements do not contain the recommended amounts of iodine. The primary purpose of the workshops was to consider the data and resources necessary to evaluate the clinical and public health benefits and risks of maternal iodine supplementation in the United States. The first workshop focused on the assessment of iodine intake, the second focused on the assessment of iodine status, and the third focused on the design and interpretation of clinical trials of maternal iodine supplementation. Here we provide the background of the ODS Iodine Initiative, summarize the 3 workshops held in 2014, and introduce the articles that arose from the workshops and are published in this supplement issue. © 2016 American Society for Nutrition.

Retrospective reconstruction of Iodine-131 distribution through the analysis of Iodine-129

NASA Astrophysics Data System (ADS)

Matsuzaki, Hiroyuki; Muramatsu, Yasuyuki; Ohno, Takeshi; Mao, Wei

2017-09-01

Iodine-131 distribution released from the Fukushima Dai-ichi Nuclear Power Plant accident was reconstructed through the iodine-129 measurements. From nearly 1,000 surface soil samples iodine was extracted by the pyro hydrolysis method. Extracted iodine was then mixed with carrier, purified and finally collected as silver iodide. Silver iodide sample was pressed into the cathode holder and set at the ion source of the MALT facility, The University of Tokyo. The isotopic ratio 129I/127I was measured by means of Accelerator Mass Spectrometry. From 129I data obtained, 131I deposition map was constructed. There observed various fine structures in the map which could not estimated neither by the simulation nor 137Cs distribution.

Mixed-layered bismuth--oxygen--iodine materials for capture and waste disposal of radioactive iodine

DOE Office of Scientific and Technical Information (OSTI.GOV)

Krumhansl, James L; Nenoff, Tina M

2015-01-06

Materials and methods of synthesizing mixed-layered bismuth oxy-iodine materials, which can be synthesized in the presence of aqueous radioactive iodine species found in caustic solutions (e.g. NaOH or KOH). This technology provides a one-step process for both iodine sequestration and storage from nuclear fuel cycles. It results in materials that will be durable for repository conditions much like those found in Waste Isolation Pilot Plant (WIPP) and estimated for Yucca Mountain (YMP). By controlled reactant concentrations, optimized compositions of these mixed-layered bismuth oxy-iodine inorganic materials are produced that have both a high iodine weight percentage and a low solubility inmore » groundwater environments.« less

Addition of chlorine during water purification reduces iodine content of drinking water and contributes to iodine deficiency.

PubMed

Samson, L; Czegeny, I; Mezosi, E; Erdei, A; Bodor, M; Cseke, B; Burman, K D; Nagy, E V

2012-01-01

Drinking water is the major natural source of iodine in many European countries. In the present study, we examined possible sites of iodine loss during the usual water purification process.Water samples from 6 sites during the technological process were taken and analyzed for iodine content. Under laboratory circumstances, prepared iodine in water solution has been used as a model to test the effect of the presence of chlorine. Samples from the purification sites revealed that in the presence of chlorine there is a progressive loss of iodine from the water. In the chlorine concentrations employed in the purification process, 24-h chlorine exposure eliminated more than 50% of iodine when the initial iodine concentration was 250 μg/l or less. Iodine was completely eliminated if the starting concentration was 16 μg/l.We conclude that chlorine used during water purification may be a major contributor to iodine deficiency in European communities.

The impact of iodine prophylaxis on thyroid 131-iodine uptake in the region of Krakow, Poland.

PubMed

Huszno, B; Hubalewska-Hoła, A; Bałdys-Waligórska, A; Sowa-Staszczak, A; Szybiński, Z

2003-01-01

Iodine prophylaxis was introduced in Poland in 1935. It was interrupted twice, the first time between 1939 and 1947 (due to the Second World War and its aftermath), and then between 1980 and 1986, due to the economical crisis in Poland at that time. A voluntary model of iodine prophylaxis (20 +/- 10 mg/kg of household salt) introduced in Poland in 1986, was followed by a mandatory model, implemented at the beginning of 1997, with 30 +/- 10 mg/kg of household salt. In the early sixties, in our Department of Endocrinology 24-hour iodine uptake test was introduced as a routine procedure for evaluating the thyroid gland. The reference value of this test increased in 1986 after discontinuation of iodine prophylaxis, and decreased in 1998, two years after re-implementation of the mandatory model of iodine prophylaxis. In 167 patients (147 with endemic goiter and 20 with no thyroid disturbances) examined between 1998 and 2000 the mean value of 24-hour iodine uptake was 27.3 +/- 10.4%, as compared to the mean value of 45,7 +/- 6.6 % in 1986. In patients with thyrotoxicosis the mean value of iodine uptake was 41.9% +/- 16.2 in 1999 (no.=614), 42.4% +/- 16.9 in 2000 (no.=644) and 37,7% +/- 17.2 at the beginning of 2001 (no.=328). The mean value of iodine uptake in patients with thyrotoxicosis before implementation of iodine prophylaxis was over 60%. The 24-hour thyroid radioiodine uptake test proved to be a useful indicator of changes of iodine intake in a iodine-deficient population. The data presented in this study confirm the importance and efficacy of the iodine prophylaxis introduced in Poland.

Biofortification of lettuce (Lactuca sativa L.) with iodine: the effect of iodine form and concentration in the nutrient solution on growth, development and iodine uptake of lettuce grown in water culture.

PubMed

Voogt, Wim; Holwerda, Harmen T; Khodabaks, Rashied

2010-04-15

Iodine is an essential trace element for humans. Two billion individuals have insufficient iodine intake. Biofortification of vegetables with iodine offers an excellent opportunity to increase iodine intake by humans. The main aim was to study the effect of iodine form and concentration in the nutrient solution on growth, development and iodine uptake of lettuce, grown in water culture. In both a winter and summer trial, dose rates of 0, 13, 39, 65, and 90 or 129 microg iodine L(-1), applied as iodate (IO(3)(-)) or iodide (I(-)), did not affect plant biomass, produce quality or water uptake. Increases in iodine concentration significantly enhanced iodine content in the plant. Iodine contents in plant tissue were up to five times higher with I(-) than with IO(3)(-). Iodine was mainly distributed to the outer leaves. The highest iodide dose rates in both trials resulted in 653 and 764 microg iodine kg(-1) total leaf fresh weight. Biofortification of lettuce with iodine is easily applicable in a hydroponic growing system, both with I(-) and IO(3)(-). I(-) was more effective than IO(3)(-). Fifty grams of iodine-biofortified lettuce would provide, respectively, 22% and 25% of the recommended daily allowance of iodine for adolescents and adults. (c) 2010 Society of Chemical Industry.

3D-PDR: Three-dimensional photodissociation region code

NASA Astrophysics Data System (ADS)

Bisbas, T. G.; Bell, T. A.; Viti, S.; Yates, J.; Barlow, M. J.

2018-03-01

3D-PDR is a three-dimensional photodissociation region code written in Fortran. It uses the Sundials package (written in C) to solve the set of ordinary differential equations and it is the successor of the one-dimensional PDR code UCL_PDR (ascl:1303.004). Using the HEALpix ray-tracing scheme (ascl:1107.018), 3D-PDR solves a three-dimensional escape probability routine and evaluates the attenuation of the far-ultraviolet radiation in the PDR and the propagation of FIR/submm emission lines out of the PDR. The code is parallelized (OpenMP) and can be applied to 1D and 3D problems.

Assessing iodine intake, iodine status, and the effects of maternal iodine supplementation: introduction to articles arising from 3 workshops held by the NIH Office of Dietary Supplements12

PubMed Central

Ershow, Abby G; Coates, Paul M; Swanson, Christine A

2016-01-01

The NIH Office of Dietary Supplements (ODS) convened 3 workshops on iodine nutrition in 2014, each held in Rockville, Maryland. These workshops were part of the ongoing ODS Iodine Initiative, begun in 2011 in response to concerns that US pregnant women may be at risk of iodine deficiency and that a high fraction of prenatal dietary supplements do not contain the recommended amounts of iodine. The primary purpose of the workshops was to consider the data and resources necessary to evaluate the clinical and public health benefits and risks of maternal iodine supplementation in the United States. The first workshop focused on the assessment of iodine intake, the second focused on the assessment of iodine status, and the third focused on the design and interpretation of clinical trials of maternal iodine supplementation. Here we provide the background of the ODS Iodine Initiative, summarize the 3 workshops held in 2014, and introduce the articles that arose from the workshops and are published in this supplement issue. PMID:27534646

Ab initio implementation of quantum trajectory mean-field approach and dynamical simulation of the N{sub 2}CO photodissociation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xie, Binbin; Liu, Lihong; Cui, Ganglong

2015-11-21

In this work, the recently introduced quantum trajectory mean-field (QTMF) approach is implemented and employed to explore photodissociation dynamics of diazirinone (N{sub 2}CO), which are based on the high-level ab initio calculation. For comparison, the photodissociation process has been simulated as well with the fewest-switches surface hopping (FSSH) and the ab initio multiple spawning (AIMS) methods. Overall, the dynamical behavior predicted by the three methods is consistent. The N{sub 2}CO photodissociation at λ > 335 nm is an ultrafast process and the two C—N bonds are broken in a stepwise way, giving birth to CO and N{sub 2} as themore » final products in the ground state. Meanwhile, some noticeable differences were found in the QTMF, FSSH, and AIMS simulated time constants for fission of the C—N bonds, excited-state lifetime, and nonadiabatic transition ratios in different intersection regions. These have been discussed in detail. The present study provides a clear evidence that direct ab initio QTMF approach is one of the reliable tools for simulating nonadiabatic dynamics processes.« less

Thyroid disorders in mild iodine deficiency.

PubMed

Laurberg, P; Nøhr, S B; Pedersen, K M; Hreidarsson, A B; Andersen, S; Bülow Pedersen, I; Knudsen, N; Perrild, H; Jørgensen, T; Ovesen, L

2000-11-01

Comparative epidemiologic studies in areas with low and high iodine intake and controlled studies of iodine supplementation have demonstrated that the major consequence of mild-to-moderate iodine deficiency for the health of the population is an extraordinarily high occurrence of hyperthyroidism in elderly subjects, especially women, with risk of cardiac arrhythmias, osteoporosis, and muscle wasting. The hyperthyroidism is caused by autonomous nodular growth and function of the thyroid gland and it is accompanied by a high frequency of goiter. Pregnant women and small children are not immediately endangered but the consequences of severe iodine deficiency for brain development are grave and a considerable safety margin is advisable. Moreover, a shift toward less malignant types of thyroid cancer and a lower radiation dose to the thyroid in case of nuclear fallout support that mild-to-moderate iodine deficiency should be corrected. However, there is evidence that a high iodine intake may be associated with more autoimmune hypothyroidism, and that Graves' disease may manifest at a younger age and be more difficult to treat. Hence, the iodine intake should be brought to a level at which iodine deficiency disorders are avoided but not higher. Iodine supplementation programs should aim at relatively uniform iodine intake, avoiding deficient or excessive iodine intake in subpopulations. To adopt such a strategy, surveillance programs are needed.

IODINE AND THE THYROID

PubMed Central

Swingle, W. W.

1919-01-01

1. Amphibian metamorphosis depends upon the amount of iodine secured by the larvæ; the greater the quantity the more rapid the differentiation. 2. Bromine is physiologically inert when fed even in large quantities to frog larvæ, hence it cannot be substituted for iodine. Bromine feeding has no effect on the thyroid. 3. Iodine is the active constituent of the thyroid gland, in the Anura at any rate, and functions within the body by stimulating intracellular oxidations; it is apparently specific in its action. 4. The basal metabolism of patients suffering from athyreosis, whose metabolism is 40 per cent below normal, is very likely held at this figure and prevented from sinking lower to the death point by the introduction of iodine into the body through food and water. 5. The thyroid gland is an organ the function of which is the extraction from the circulation, storage, and supplying to the organism, under the pressure of its needs, the small quantities of iodine taken into the body. The chief function of this gland then is the utilization of iodine in small quantities. PMID:19871773

Accurate quantum yields by laser gain vs absorption spectroscopy - Investigation of Br/Br(asterisk) channels in photofragmentation of Br2 and IBr

NASA Technical Reports Server (NTRS)

Haugen, H. K.; Weitz, E.; Leone, S. R.

1985-01-01

Various techniques have been used to study photodissociation dynamics of the halogens and interhalogens. The quantum yields obtained by these techniques differ widely. The present investigation is concerned with a qualitatively new approach for obtaining highly accurate quantum yields for electronically excited states. This approach makes it possible to obtain an accuracy of 1 percent to 3 percent. It is shown that measurement of the initial transient gain/absorption vs the final absorption in a single time-resolved signal is a very accurate technique in the study of absolute branching fractions in photodissociation. The new technique is found to be insensitive to pulse and probe laser characteristics, molecular absorption cross sections, and absolute precursor density.

REMPI detection of singlet oxygen 1O2 arising from UV-photodissociation of van der Waals complex isoprene-oxygen C5H8-O2

NASA Astrophysics Data System (ADS)

Bogomolov, Alexandr S.; Dozmorov, Nikolay V.; Kochubei, Sergei A.; Baklanov, Alexey V.

2018-01-01

The one-laser two-color resonance enhanced multiphoton ionization REMPI [(1 + 1‧) + 1] and velocity map imaging have been applied to investigate formation of molecular oxygen in excited singlet O2(a1Δg) and ground O2(X3Σg-) states in the photodissociation of van der Waals complex isoprene-oxygen C5H8-O2. These molecules were found to appear in the different rotational states with translational energy varied from a value as low as ∼1 meV to a distribution with temperature of about 940 K. The observed traces of electron recoil in the images of photoions reveal participation of several ionization pathways of the resonantly excited intermediate states of O2.

Observing iodine monoxide from satellite

NASA Astrophysics Data System (ADS)

Schoenhardt, Anja; Richter, Andreas; Begoin, Mathias; Wittrock, Folkard; Burrows, John P.

Iodine and iodine monoxide (IO) belong to the group of reactive halogen species, and they may impact on atmospheric chemical composition and the radiation budget. Vice versa, sur-rounding conditions may influence the emissions and pathways of iodine compounds. Although atmospheric amounts of iodine are typically fairly small, the impact may still be substantial. Iodine radicals are photolytically released from precursors and may then cause catalytic ozone depletion. In this reaction with ozone, IO is produced, a molecule which plays a central role in the iodine cycling. Via self reactions of IO, higher iodine oxides form and initiate the formation of new particles, which may change the atmospheric radiation balance. Apart from that, many living species, including human beings, vertebrates in general, but also micro-and macroalgae species, e.g., depend on the supply with iodine. Consequently, it is necessary to understand the cycling of iodine through the different components of the Earth system. Although increas-ing research effort in the form of field, laboratory and modeling studies has strongly improved our knowledge and understanding of iodine abundances and impact, still many open questions remain. The relevance of iodine on a global scale is not well known yet; sources are not well quantified and release processes are not fully understood. Since recently, IO may be observed from space by the SCIAMACHY instrument on the EN-VISAT satellite, which is in a near-polar, sun-synchronous orbit. Nadir observations from SCIAMACHY have been analysed for the IO absorption signature in the visible wavelength range for several mission years. IO amounts are typically close to the limit of detectability of SCIAMACHY. Detecting such small quantities, careful attention needs to be paid to system-atic errors, spectral correlations and resulting retrieval artefacts. Subsequently, appropriate temporal averaging is utilised to improve the signal-to-noise ratio. The resulting

Iodine deficiency in Saudi Arabia.

PubMed

Al-Nuaim, A R; Al-Mazrou, Y; Kamel, M; Al-Attas, O; Al-Daghari, N; Sulimani, R

1997-05-01

Data on the status of iodine deficiency in the Arabian peninsula is scarce. We have conducted a cross-sectional national epidemiological survey in Saudi Arabia to study the iodine status of Saudi schoolchildren, between eight and ten years, who were randomly selected, after taking into consideration the gender, provincial population and area distribution. Casual urine samples were collected and sent to the central laboratory for analysis. Clinical assessment for the presence of goiter was conducted in four areas with different geographical natures. The survey included 4638 subjects, and their median and mean (SD) of urinary iodine concentration was 18 and 17 m g/dL, respectively. We found provincial differences with respect to urinary iodine concentration and the percentage of subjects with urinary iodine concentration <10 m g/dL. The Southern province had the lowest median (11 m g/dL) and the highest percentage (45%) of subjects with urinary iodine concentration <10 m g/dL. On the other hand, subjects of the Western province had the highest median (24 m g/dL) and the lowest percentage (8%) of subjects with urinary iodine concentration <10 m g/dL. The clinical assessment revealed that the highest prevalence and more advanced grade of goiter (22%, 95% CI 19-25, grade 1; 8%, 95% CI 6-10, grade 2) was found in the Asir region, a high-altitude area in the Southern province. The lowest prevalence of goiter (4%, 95% CI 0.8-7.2, grade 1) was found in Gizan, an urban coastal community. There was a significant relationship between the prevalence of goiter and the urinary iodine concentration. The survey for iodine deficiency disorder (IDD) in Saudi Arabia has shown a mild degree of iodine deficiency in the Southern province. Odds ratio (OR) was used to study the statistical relationship between the prevalence of goiter and the urinary iodine concentration. There is a need to launch a control program to ensure the exclusive availability of iodized salt in Saudi Arabia

Iodine addition using triiodide solutions

NASA Technical Reports Server (NTRS)

Rutz, Jeffrey A.; Muckle, Susan V.; Sauer, Richard L.

1992-01-01

The study develops: a triiodide solution for use in preparing ground service equipment (GSE) water for Shuttle support, an iodine dissolution method that is reliable and requires minimal time and effort to prepare, and an iodine dissolution agent with a minimal concentration of sodium salt. Sodium iodide and hydriodic acid were both found to dissolve iodine to attain the desired GSE iodine concentrations of 7.5 +/- 2.5 mg/L and 25 +/- 5 mg/L. The 1.75:1 and 2:1 sodium iodide solutions produced higher iodine recoveries than the 1.2:1 hydriodic acid solution. A two-hour preparation time is required for the three sodium iodide solutions. The 1.2:1 hydriodic acid solution can be prepared in less than 5 min. Two sodium iodide stock solutions (2.5:1 and 2:1) were found to dissolve iodine without undergoing precipitation.

Injection of iodine to the stratosphere

NASA Astrophysics Data System (ADS)

Saiz-Lopez, Alfonso; Baidar, Sunil; Cuevas, Carlos A.; Koening, Theodore; Fernandez, Rafael P.; Dix, Barbara; Kinnison, Douglas E.; Lamarque, Jean-Francois; Rodriguez-Lloveras, Xavier; Campos, Teresa L.; Volkamer, Rainer

2016-04-01

There are still many uncertainties about the influence of iodine chemistry in the stratosphere, as the real amount of reactive iodine injected to this layer the troposphere and the partitioning of iodine species are still unknown. In this work we report a new estimation of the injection of iodine into the stratosphere based on novel daytime (SZA < 45°) aircraft observations in the tropical tropopause layer (TORERO campaign) and a 3D global chemistry-climate model (CAM-Chem) with the most recent knowledge about iodine photochemistry. The results indicate that significant levels of total reactive iodine (0.25-0.7 pptv), between 2 and 5 times larger than the accepted upper limits, could be injected into the stratosphere via tropical convective outflow. At these iodine levels, modelled iodine catalytic cycles account for up to 30% of the contemporary ozone loss in the tropical lower stratosphere and can exert a stratospheric ozone depletion potential equivalent or even larger than that of very short-lived bromocarbons. Therefore, we suggest that iodine sources and chemistry need to be considered in assessments of the historical and future evolution of the stratospheric ozone layer.

High sensitive pulse oximeter-spectrophotometer for laser-optical dosimetry in biology and medicine

NASA Astrophysics Data System (ADS)

Asimov, M. M.; Asimov, R. M.; Rubinov, A. N.; Mamilov, S. A.; Plaksiy, Yu. S.

2006-03-01

High sensitive multi channel pulse oxymeter - spectrophotometer for control of the local tissue oxygen saturation is presented. Due to an original method of data storing and processing the accuracy of measurements 3-4 times are increased in compare with similar systems. This system is used for registration of the local changes of arterial blood saturation with oxygen under effect of low intensity laser radiation. It is shown that the photodissociation of oxyhemoglobin in cutaneous blood vessels play a dominant role in the mechanism of biostimulating and therapeutic effect of low intensity laser radiation. The results of experimental investigation in vivo the dependence of arterial oxygen blood saturation on temperature and the wavelength of laser radiation are presented. It is suggested that dosimetry for laser therapy could be base on regulation of local concentration of free oxygen in tissue.

The importance of iodine nutrition during pregnancy.

PubMed

Glinoer, Daniel

2007-12-01

To examine the importance of iodine nutrition during pregnancy. Review of existing literature of iodine in pregnancy. Population surveys and metabolic studies. Pregnant women. The main changes in thyroid function associated with pregnancy are due to an increase in hormone requirements that begin in the first trimester of gestation. This increase can only be met by a proportional increase in hormone production, something that depends directly upon the availability of iodine. When dietary iodine is lacking, an adequate physiological adaptation is difficult to achieve and is progressively replaced by pathological alterations that occur in parallel with the degree and duration of iodine deprivation. Iodine prophylaxis should be given systematically to women during pregnancy. In most public health programmes dealing with the correction of iodine deficiency disorders, iodised salt has been used as the preferred means to deliver iodine to households. Iodised salt, however, is not the ideal means of delivering iodine in the specific instances of pregnancy, breast-feeding and complementary feeding because of the need to limit salt intake during these periods. In European countries, presently it is proposed that iodine is given to pregnant women and breast-feeding mothers by systematically administering multivitamin tablets containing iodine in order to reach the recommended dietary allowance of 250 microg iodine day-1.

The OH rotational population and photodissociation of H{sub 2}O in DG Tauri

DOE Office of Scientific and Technical Information (OSTI.GOV)

Carr, John S.; Najita, Joan R.

2014-06-10

We analyze the OH rotational emission in the Spitzer Space Telescope mid-infrared spectrum of the T Tauri star DG Tau. OH is observed in emission from upper level energies of 1900 K to 28,000 K. The rotational diagram cannot be fit with any single combination of temperature and column density and has slopes that correspond to excitation temperatures ranging from 200 K to 6000 K. The relative Λ-doublet population within each rotational level is not equal, showing that the OH population is not in thermal equilibrium. The symmetric Λ-doublet state is preferred in all rotational states, with an average ofmore » 0.5 for the population ratio of the anti-symmetric to symmetric state. We show that the population distribution of the high rotational lines and the Λ-doublet ratio are consistent with the formation of OH following the photo-dissociation of H{sub 2}O by FUV photons in the second absorption band of water (∼1150-1400 Å), which includes Lyα. Other processes, OH formation from either photo-dissociation of water in the first absorption band (1450-1900 Å) or the reaction O({sup 1} D) + H{sub 2}, or collisional excitation, cannot explain the observed emission in the high rotational states but could potentially contribute to the population of lower rotational levels. These results demonstrate that the photodissociation of water is active in DG Tau and support the idea that the hot rotational OH emission commonly observed in Classical T Tauri stars is due to the dissociation of H{sub 2}O by FUV radiation.« less

Air Density Measurements in a Mach 10 Wake Using Iodine Cordes Bands

NASA Technical Reports Server (NTRS)

Balla, Robert J.; Everhart, Joel L.

2012-01-01

An exploratory study designed to examine the viability of making air density measurements in a Mach 10 flow using laser-induced fluorescence of the iodine Cordes bands is presented. Experiments are performed in the NASA Langley Research Center 31 in. Mach 10 air wind tunnel in the hypersonic near wake of a multipurpose crew vehicle model. To introduce iodine into the wake, a 0.5% iodine/nitrogen mixture is seeded using a pressure tap at the rear of the model. Air density was measured at 56 points along a 7 mm line and three stagnation pressures of 6.21, 8.62, and 10.0 MPa (900, 1250, and 1450 psi). Average results over time and space show rho(sub wake)/rho(sub freestream) of 0.145 plus or minus 0.010, independent of freestream air density. Average off-body results over time and space agree to better than 7.5% with computed densities from onbody pressure measurements. Densities measured during a single 60 s run at 10.0 MPa are time-dependent and steadily decrease by 15%. This decrease is attributed to model forebody heating by the flow.

[Iodine intake in Portuguese school children].

PubMed

Limbert, Edward; Prazeres, Susana; São Pedro, Márcia; Madureira, Deolinda; Miranda, Ana; Ribeiro, Manuel; Carrilho, Francisco; Jácome de Castro, J; Lopes, Maria Santana; Cardoso, João; Carvalho, Andre; Oliveira, Maria João; Reguengo, Henrique; Borges, Fátima

2012-01-01

The aim of the present study was to evaluate iodine intake in portuguese school children in order to inform health authorities of eventual measures to be implemented. Iodine is the key element for thyroid hormone synthesis and its deficiency even mild, as found in other European countries, may have deleterious effects in pregnancy resulting in cognitive problems of offsprings. In Portugal there are no recent data on iodine intake in schoolchildren. 3680 children aged 6-12 years of both sexes, from 78 different schools were studied. Iodine intake was evaluated trough urine iodine (UI) determinations using a colorimetic method. The global median UI value was 105.5 µg/L; the percentage of children with UI <100 µg/L was 47.1%, corresponding to 41% of the studied schools. The percentage of values <50 µg/L was 11.8%. The male gender, the south region of the country and the distribution of milk in school were significantly linked with a higher iodine elimination. Our global results point to a borderline/ mildly insufficient iodine intake in the portuguese school population. However 47% of the children had UI under 100 µg /L. The comparison of our results with the available data from 30 years ago, point to a considerable improvement, due to silent prophylaxis. Male gender, geographical area and milk distribution influenced positively iodine intake.The importance of milk has been referred in numerous papers. The study of UI in the Portuguese school population points to a borderline iodine intake. However, in 47% of children iodine intake was inadequate. Compared with data from the eighties, a considerable increase in iodine elimination was found. Taking into account the potencial deleterious effects of inadequate iodine intake, a global prophylaxis with salt iodization has to be considered.

Calculations on Isotope Separation by Laser Induced Photodissociation of Polyatomic Molecules. Final Report

DOE R&D Accomplishments Database

Lamb, W. E. Jr.

1978-11-01

This report describes research on the theory of isotope separation produced by the illumination of polyatomic molecules by intense infrared laser radiation. Newton`s equations of motion were integrated for the atoms of the SF{sub 6} molecule including the laser field interaction. The first year`s work has been largely dedicated to obtaining a suitable interatomic potential valid for arbitrary configurations of the seven particles. This potential gives the correct symmetry of the molecule, the equilibrium configuration, the frequencies of the six distinct normal modes of oscillation and the correct (or assumed) value of the total potential energy of the molecule. Other conditions can easily be imposed in order to obtain a more refined potential energy function, for example, by making allowance for anharmonicity data. A suitable expression was also obtained for the interaction energy between a laser field and the polyatomic molecule. The electromagnetic field is treated classically, and it would be easily possible to treat the cases of time dependent pulses, frequency modulation and noise.

Iodine Propulsion Advantages for Low Cost Mission Applications and the Iodine Satellite (ISAT) Technology Demonstration

NASA Technical Reports Server (NTRS)

Dankanich, John W.; Schumacher, Daniel M.

2015-01-01

The NASA Marshall Space Flight Center Science and Technology Office is continuously exploring technology options to increase performance or reduce cost and risk to future NASA missions including science and exploration. Electric propulsion is a prevalent technology known to reduce mission costs by reduction in launch costs and spacecraft mass through increased post launch propulsion performance. The exploration of alternative propellants for electric propulsion continues to be of interest to the community. Iodine testing has demonstrated comparable performance to xenon. However, iodine has a higher storage density resulting in higher ?V capability for volume constrained systems. Iodine's unique properties also allow for unpressurized storage yet sublimation with minimal power requirements to produce required gas flow rates. These characteristics make iodine an ideal propellant for secondary spacecraft. A range of mission have been evaluated with a focus on low-cost applications. Results highlight the potential for significant cost reduction over state of the art. Based on the potential, NASA has been developing the iodine Satellite for a near-term iodine Hall propulsion technology demonstration. Mission applications and progress of the iodine Satellite project are presented.

The Iodine Content in Urine, Faeces and Selected Organs of Rats Fed Lettuce Biofortified with Iodine Through Foliar Application.

PubMed

Rakoczy, Roksana; Kopeć, Aneta; Piątkowska, Ewa; Smoleń, Sylwester; Skoczylas, Łukasz; Leszczyńska, Teresa; Sady, Włodzimierz

2016-12-01

Iodine is an essential trace element for humans. Foliar application of micronutrients is successfully used in order to increase the concentration of essential elements in vegetables. The aim of this study was to evaluate the iodine absorption in the rat organism fed foliar biofortified lettuce. The presented study was consisted of the vegetative and animal experiment. In the vegetative experiment with lettuce, two combinations of foliar application were used: (1) control-without iodine application and (2) iodine application in the potassium iodide (KI) form. In the animal experiment, Wistar rats were divided to four groups, which received one of four diets: (1) C-control diet containing iodine in the KI form, (2) D-diet deficient in iodine, (3) D + BL-diet containing biofortified lettuce, and (4) D + CL-diet containing control lettuce (as the only source of iodine in diet, respectively). The diets contained 0.260, 0.060, 0.254 and 0.075 mg I/kg, respectively. In order to determine the iodine absorption in the rat organisms, the content of this trace element was measured in urine, faeces and in selected organs with the use of the ICP-OES technique. Foliar application of the KI increased the content of iodine in lettuce. The rats from the D + BL group excreted significantly less iodine in their urine and faeces and also accumulated more iodine in the organs than the rats from the C group. Iodine with biofortified lettuce was much bioavailable for rodents than iodine from control diet. Biofortified lettuce can be a source of iodine in a diet of human and can improve iodine nutrition.

Molecular laser stabilization for LISA

NASA Astrophysics Data System (ADS)

Halloin, Hubert; Acef, Ouali; Argence, Berengere; Jeannin, Olivier; Prat, Pierre; de Vismes, Eden; Plagnol, Eric; Brillet, Alain; Mondin, Linda; Berthon, Jacques; Turazza, Oscar

2017-11-01

The expected performance of LISA relies on two main technical challenges: the ability for the spacecrafts to precisely follow the free-flying masses and the outstanding precision of the phase shift measurement. This latter constraint requires frequency stabilized lasers and efficient numerical algorithms to account for the redundant, delayed noise propagation, thus cancelling laser phase noise by many orders of magnitude (TDI methods). Recently involved in the technical developments for LISA, the goal of our team at APC (France) is to contribute on these two subjects: frequency reference for laser stabilization and benchtop simulation of the interferometer. In the present design of LISA, two stages of laser stabilization are used (not accounting for the "post-processed" TDI algorithm): laser pre-stabilization on a frequency reference and lock on the ultra stable distance between spacecrafts (arm-locking). While the foreseen (and deeply studied) laser reference consists of a Fabry-Perot cavity, other techniques may be suitable for LISA or future metrology missions. In particular, locking to a molecular reference (namely iodine in the case of the LISA Nd:YAG laser) is an interesting alternative. It offers the required performance with very good long-term stability (absolute frequency reference) though the reference can be slightly tuned to account for arm-locking. This technique is currently being investigated by our team and optimized for LISA (compactness, vacuum compatibility, ease of use and initialization, etc.). A collaboration with a French laboratory (the SYRTE) had been started aiming to study a second improved technique consisting in inserting the iodine cell in a Fabry-Perot cavity. Ongoing results and prospects to increase the performance of the system are presented in the present article.

A compact frequency stabilized telecom laser diode for space applications

NASA Astrophysics Data System (ADS)

Philippe, C.; Holleville, D.; Le Targat, R.; Wolf, P.; Leveque, T.; Le Goff, R.; Martaud, E.; Acef, O.

2017-09-01

We report on a Telecom laser diode (LD) frequency stabilization to a narrow iodine hyperfine line in the green range, after frequency tripling process using fibered nonlinear waveguide PPLN crystals. We have generated up to 300 mW optical power in the green range ( 514 nm) from 800 mW of infrared power ( 1542 nm), corresponding to a nonlinear conversion efficiency h = P3?/P? 36%. Less than 10 mW of the generated green power are used for Doppler-free spectroscopy of 127I2 molecular iodine, and -therefore- for the frequency stabilization purpose. The frequency tripling optical setup is very compact (< 5 l), fully fibered, and could operate over the full C-band of the Telecom range (1530 nm - 1565 nm). Several thousands of hyperfine iodine lines may thus be interrogated in the 510 nm - 521 nm range. We build up an optical bench used at first in free space configuration, using the well-known modulation transfer spectroscopy technique (MTS), in order to test the potential of this new frequency standard based on the couple "1.5 ?m laser / iodine molecule". We have already demonstrated a preliminary frequency stability of 4.8 x 10-14 ? -1/2 with a minimum value of 6 x 10-15 reached after 50 s of integration time, conferred to a laser diode operating at 1542.1 nm. We focus now our efforts to expand the frequency stability to a longer integration time in order to meet requirements of many space experiments, such earth gravity missions, inters satellites links or space to ground communications. Furthermore, we investigate the potential of a new approach based on frequency modulation technique (FM), associated to a 3rd harmonic detection of iodine lines to increase the compactness of the optical setup.

Chalcogenide aerogels as sorbents for radioactive iodine

DOE Office of Scientific and Technical Information (OSTI.GOV)

Subrahmanyam, Kota S.; Sarma, Debajit; Malliakas, Christos

Iodine (129I) is one of the radionuclides released in nuclear fuel reprocessing and poses risk to public safety due to its involvement in human metabolic processes. In order to prevent the leaching of hazardous radioactive iodine into the environment, its effective capture and sequestration is pivotal. In the context of finding a suitable matrix for capturing radioactive iodine the chalcogels, NiMoS4, CoMoS4, Sb4Sn4S12, Zn2Sn2S6, and CoSx (x = 4-5) were explored as iodine sorbents. All the chalcogels showed high uptake, reaching up to 225 mass% (2.25 g/g) of the final mass owing to strong chemical and physical iodine-chalcogen interactions. Analysismore » of the iodine-loaded specimens revealed that the iodine chemically reacted with Sb4Sn4S12, Zn2Sn2S6, and CoSx to form metal complexes SbI3, SnI4, and, KI respectively. The NiMoS4 and CoMoS4 chalcogels did not appear to undergo a chemical reaction with iodine since iodide complexes were not observed with these samples. Once heated, the iodine-loaded chalcogels released iodine in the temperature range of 75 °C to 220 °C, depending on the nature of iodine speciation. In the case of Sb4Sn4S12 and Zn2Sn2S6 iodine release was observed around 150 °C in the form of SnI4 and SbI3, respectively. The NiMoS4, CoMoS4, and CoSx released iodine at ~75 °C, which is consistent with physisorbed iodine. Preliminary investigations on consolidation of iodine-loaded Zn2Sn2S6 with Sb2S3 as a glass forming additive showed the content of iodine in consolidated glass ingots at around 25 mass%.« less

ROVIBRATIONALLY RESOLVED DIRECT PHOTODISSOCIATION THROUGH THE LYMAN AND WERNER TRANSITIONS OF H{sub 2} FOR FUV/X-RAY-IRRADIATED ENVIRONMENTS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gay, C. D.; Porter, R. L.; Stancil, P. C.

Using ab initio potential curves and dipole transition moments, cross-section calculations were performed for the direct continuum photodissociation of H{sub 2} through the B{sup 1}{Sigma}{sup +}{sub u} <- X{sup 1}{Sigma}{sup +}{sub g} (Lyman) and C{sup 1}{Pi}{sub u} <- X{sup 1}{Sigma}{sup +}{sub g} (Werner) transitions. Partial cross-sections were obtained for wavelengths from 100 A to the dissociation threshold between the upper electronic state and each of the 301 bound rovibrational levels v''J'' within the ground electronic state. The resulting cross-sections are incorporated into three representative classes of interstellar gas models: diffuse clouds, photon-dominated regions, and X-ray-dominated regions (XDRs). The models, whichmore » used the CLOUDY plasma/molecular spectra simulation code, demonstrate that direct photodissociation is comparable to fluorescent dissociation (or spontaneous radiative dissociation, the Solomon process) as an H{sub 2} destruction mechanism in intense far-ultraviolet or X-ray-irradiated gas. In particular, changes in H{sub 2} rotational column densities are found to be as large as 20% in the XDR model with the inclusion of direct photodissociation. The photodestruction rate from some high-lying rovibrational levels can be enhanced by pumping from H Ly{beta} due to a wavelength coincidence with cross-section resonances resulting from quasi-bound levels of the upper electronic states. Given the relatively large size of the photodissociation data set, a strategy is described to create truncated, but reliable, cross-section data consistent with the wavelength resolving power of typical observations.« less

Solar-pumped gas laser development

NASA Technical Reports Server (NTRS)

Wilson, J. W.

1980-01-01

A survey of gas properties through detailed kinetic models led to the identification of critical gas parameters for use in choosing appropriate gas combinations for solar pumped lasers. Broadband photoabsorption in the visible or near UV range is required to excite large volumes of gas and to insure good solar absorption efficiency. The photoexcitation density is independent of the absorption bandwidth. The state excited must be a metastable state which is not quenched by the parent gas. The emission bandwidth must be less than 10 A to insure lasing threshold over reasonable gain lengths. The system should show a high degree of chemical reversibility and an insensitivity to increasing temperature. Other properties such as good quantum efficiency and kinetic efficiency are also implied. Although photoexcitation of electronic vibrational transitions is considered as a possible system if the emission bands sufficiently narrow, it appears that photodissociation into atomic metastables is more likely to result in a successful solar pumped laser system.

Oxygen isotope fractionation in the vacuum ultraviolet photodissociation of carbon monoxide: Wavelength, pressure and temperature dependency.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chakraborty, Subrata; Davis, Ryan; Ahmed, Musahid

Several absorption bands exist in the VUV region of Carbon monoxide (CO). Emission spectra indicate that these bands are all predissociative. An experimental investigation of CO photodissociation by vacuum ultraviolet photons (90 to 108 nm; ~13 to 11 eV) from the Advanced Light Source Synchrotron and direct measurement of the associated oxygen isotopic composition of the products are presented here. A wavelength dependency of the oxygen isotopic composition in the photodissociation product was observed. Slope values (δ'{sup 18}O/ δ'{sup 17}O) ranging from 0.76 to 1.32 were observed in oxygen three-isotope space (δ'{sup 18}O vs. δ'{sup 17}O) which correlated with increasingmore » synchrotron photon energy, and indicate a dependency of the upper electronic state specific dissociation dynamics (e.g., perturbation and coupling associated with a particular state). An unprecedented magnitude in isotope separation was observed for photodissociation at the 105 and 107 nm synchrotron bands and are found to be associated with accidental predissociation of the vibrational states ({nu} = 0 and 1) of the upper electronic state E{sup 1}Π. For each synchrotron band, a large (few hundred per mil) extent of isotopic fractionation was observed and the range of fractionation is a combination of column density and exposure time. A significant temperature dependency in oxygen isotopic fractionation was observed, indicating a rotational level dependency in the predissociation process.« less

Characterization of low-molecular weight iodine-terminated polyethylenes by gas chromatography/mass spectrometry and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry with the use of derivatization.

PubMed

Zaikin, Vladimir G; Borisov, Roman S; Polovkov, Nikolai Yu; Zhilyaev, Dmitry I; Vinogradov, Aleksei A; Ivanyuk, Aleksei V

2013-01-01

Gas chromatography/mass spectrometry (GC/MS) and matrix-assisted laser desorption/ionization time-of-flight (MALDI-ToF) mass spectrometry, in conjunction with various derivatization approaches, have been applied to structure determination of individual oligomers and molecular-mass distributions (MMD) in low-molecular mass polyethylene having an iodine terminus. Direct GC/MS analysis has shown that the samples under investigation composed of polyethyelene-iodides (major components) and n-alkanes. Exchange reaction with methanol in the presence of NaOH gave rise to methoxy-derivatives and n-alkenes. Electron ionization mass spectra have shown that the former contained terminal methoxy groups indicating the terminal position of the iodine atom in the initial oligomers. MMD parameters have been determined with the aid of MALDI mass spectrometry followed by preliminary derivatization-formation of covalently bonded charge through the reaction of iodides with triphenylphosphine, trialkylamines, pyridine or quinoline. The mass spectra revealed well-resolved peaks for cationic parts of derivatized oligomers allowing the determination of MMD. The latter values have been compared with those calculated from GC/MS data.

Iodine deficiency disorders in Sarawak, Malaysia.

PubMed

Kiyu, A; Tambi, Z; Ahmad, Y

1998-12-01

The state of Sarawak in Malaysia has a high prevalence of iodine deficiency disorders (IDD). This has been revealed through a review of goitre surveys that were carried out in the State from the early 1970s to the 1990s. The primary cause was low iodine intake. Contributory factors were low iodine content in the soil and water as well as high cassava consumption. Virtual elimination of IDD is one of the nutritional goals of the IDD prevention and control programs. The strategies adopted include the iodination of coarse salt, which is sold in the market by shopkeepers and also provided free from government health clinics; legislation requiring that salt sold in IDD-gazetted areas must be iodised; and the use of iodinators to iodise water supplied by the gravity-feed system to villages and boarding schools in rural areas. The indicators used in the monitoring and evaluation of the program include the availability of iodised salt in the market and households, iodine levels in water supply that had been fitted with iodinators, goitre volume measured by ultrasound, and urinary iodine excretion among school children.

The I2 dissociation mechanisms in the chemical oxygen-iodine laser revisited.

PubMed

Waichman, K; Barmashenko, B D; Rosenwaks, S

2012-06-28

The recently suggested mechanism of I(2) dissociation in the chemical oxygen-iodine laser (COIL) [K. Waichman, B. D. Barmashenko, and S. Rosenwaks, J. Appl. Phys. 106, 063108 (2009); and J. Chem. Phys. 133, 084301 (2010)] was largely based on the suggestion of V. N. Azyazov, S. Yu. Pichugin, and M. C. Heaven [J. Chem. Phys. 130, 104306 (2009)] that the vibrational population of O(2)(a) produced in the chemical generator is high enough to play an essential role in the dissociation. The results of model calculations based on this mechanism agreed very well with measurements of the small signal gain g, I(2) dissociation fraction F, and temperature T in the COIL. This mechanism is here revisited, following the recent experiments of M. V. Zagidullin [Quantum Electron. 40, 794 (2010)] where the observed low population of O(2)(b, v = 1) led to the conclusion that the vibrational population of O(2)(a) at the outlet of the generator is close to thermal equilibrium value. This value corresponds to a very small probability, ∼0.05, of O(2)(a) energy pooling to the states O(2)(X,a,b, v > 0). We show that the dissociation mechanism can reproduce the experimentally observed values of g, F, and T in the COIL only if most of the energy released in the processes of O(2)(a) energy pooling and O(2)(b) quenching by H(2)O ends up as vibrational energy of the products, O(2)(X,a,b), where the vibrational states v = 2 and 3 are significantly populated. We discuss possible reasons for the differences in the suggested vibrational population and explain how these differences can be reconciled.

Direct evidence for coastal iodine particles from Laminaria macroalgae - linkage to emissions of molecular iodine

NASA Astrophysics Data System (ADS)

McFiggans, G.; Coe, H.; Burgess, R.; Allan, J.; Cubison, M.; Alfarra, M. R.; Saunders, R.; Saiz-Lopez, A.; Plane, J. M. C.; Wevill, D.; Carpenter, L.; Rickard, A. R.; Monks, P. S.

2004-05-01

Renewal of ultrafine aerosols in the marine boundary layer may lead to repopulation of the marine distribution and ultimately determine the concentration of cloud condensation nuclei (CCN). Thus the formation of nanometre-scale particles can lead to enhanced scattering of incoming radiation and a net cooling of the atmosphere. The recent demonstration of the chamber formation of new particles from the photolytic production of condensable iodine-containing compounds from diiodomethane (CH2I2), (O'Dowd et al., 2002; Kolb, 2002; Jimenez et al., 2003a; Burkholder and Ravishankara, 2003), provides an additional mechanism to the gas-to-particle conversion of sulphuric acid formed in the photo-oxidation of dimethylsulphide for marine aerosol repopulation. CH2I2 is emitted from seaweeds (Carpenter et al., 1999, 2000) and has been suggested as an initiator of particle formation. We demonstrate here for the first time that ultrafine iodine-containing particles are produced by intertidal macroalgae exposed to ambient levels of ozone. The particle composition is very similar both to those formed in the chamber photo-oxidation of diiodomethane and in the oxidation of molecular iodine by ozone. The particles formed in all three systems are similarly aspherical. When small, those formed in the molecular iodine system swell only moderately when exposed to increased humidity environments, and swell progressively less with increasing size; this behaviour occurs whether they are formed in dry or humid environments, in contrast to those in the CH2I2 system. Direct coastal boundary layer observations of molecular iodine, ultrafine particle production and iodocarbons are reported. Using a newly measured molecular iodine photolysis rate, it is shown that, if atomic iodine is involved in the observed particle bursts, it is of the order of at least 1000 times more likely to result from molecular iodine photolysis than diiodomethane photolysis. A hypothesis for molecular iodine release from

Intravascular enhancement with identical iodine delivery rate using different iodine contrast media in a circulation phantom.

PubMed

Mihl, Casper; Wildberger, Joachim E; Jurencak, Tomas; Yanniello, Michael J; Nijssen, Estelle C; Kalafut, John F; Nalbantov, Georgi; Mühlenbruch, Georg; Behrendt, Florian F; Das, Marco

2013-11-01

Both iodine delivery rate (IDR) and iodine concentration are decisive factors for vascular enhancement in computed tomographic angiography. It is unclear, however, whether the use of high-iodine concentration contrast media is beneficial to lower iodine concentrations when IDR is kept identical. This study evaluates the effect of using different iodine concentrations on intravascular attenuation in a circulation phantom while maintaining a constant IDR. A circulation phantom with a low-pressure venous compartment and a high-pressure arterial compartment simulating physiological circulation parameters was used (heart rate, 60 beats per minute; stroke volume, 60 mL; blood pressure, 120/80 mm Hg). Maintaining a constant IDR (2.0 g/s) and a constant total iodine load (20 g), prewarmed (37°C) contrast media with differing iodine concentrations (240-400 mg/mL) were injected into the phantom using a double-headed power injector. Serial computed tomographic scans at the level of the ascending aorta (AA), the descending aorta (DA), and the left main coronary artery (LM) were obtained. Total amount of contrast volume (milliliters), iodine delivery (grams of iodine), peak flow rate (milliliter per second), and intravascular pressure (pounds per square inch) were monitored using a dedicated data acquisition program. Attenuation values in the AA, the DA, and the LM were constantly measured (Hounsfield unit [HU]). In addition, time-enhancement curves, aortic peak enhancement, and time to peak were determined. All contrast injection protocols resulted in similar attenuation values: the AA (516 [11] to 531 [37] HU), the DA (514 [17] to 531 [32] HU), and the LM (490 [10] to 507 [17] HU). No significant differences were found between the AA, the DA, and the LM for either peak enhancement (all P > 0.05) or mean time to peak (AA, 19.4 [0.58] to 20.1 [1.05] seconds; DA, 21.1 [1.0] to 21.4 [1.15] seconds; LM, 19.8 [0.58] to 20.1 [1.05] seconds). This phantom study demonstrates that

Velocity measurement in rocket exhaust and general aerodynamic flows by photolysis of H2O and laser induced fluorescence of OH

NASA Technical Reports Server (NTRS)

Boedeker, Laurence R.

1992-01-01

A 'tagging' approach in which the photolysis of H2O by an excimer laser creates a zone of enhanced OH concentration, while a second, pulsed-UV laser detects tagged-zone convection via time-delayed excitation of OH fluorescence, depends on the photodissociation process and the kinetics of OH decay (relative to velocity). For application to the fuel-rich, high supersonic Mach number exhaust flow of the SSME, the detection of OH is being accomplished with either a pulsed narrowband UV dye laser or a tunable XeCl excimer laser for excitation of an OH 0-0 band transition, while the two-photon photolysis of H2O is conducted by focusing an injection-locked KrF excimer laser into the flow.

Values of iodine metabolism biomarkers in assessing the iodine nutrition status in surgically treated patients with thyroid disease.

PubMed

Han, Jian-hua; Wu, Lian; Yu, Song-lin; Fang, Hui-ling; Kamg, Wei-ming; Cheng, Xin-qi; Lu, Jie; Yu, Jian-chun; Qiu, Ling

2015-04-01

To assess the clinical application value of iodine metabolism biomarkers in assessing iodine nutrition status in surgically treated patients with thyroid disease. Blood,morning urine and 24-hour urine samples were collected in 31 healthy volunteers and in 30 surgically treated patients with thyroid disease before and after surgery. Iodine concentration was analyzed by inductively coupled plasma mass spectrometry. The iodine metabolism biomarkers including serum iodine (SI), morning urine iodine(UI), morning urine iodine/urine creatinine ratio (UI/UCr), 24-hour urine iodine (24 h UI), and 24-hour urine iodine excretion (24 h UIE) were evaluated in these two groups. In addition, the validation coincidence rate of iodine metabolism biomarkers in healthy volunteers to different reference ranges including World Health Organization, Mayo Clinic, and Quest Diagnostics were calculated. The UI/UCr ratio of pre-operative thyroid disease patients was significantly lower than that of healthy volunteers (P<0.05), while the other biomarkers showed no significant differences (all P>0.05) between these two groups. The SI, UI ,and 24 h UI in postoperative thyroid disease patients were significantly higher than those of the pre-operative patients (all P<0.05). Though the medians of all biomarkers in healthy volunteers were within the reference ranges,only the validation coincidence rates of SI, UI, and UI/UCr in the 41-70-year populations were over than 90% according to Mayo Clinic; furthermore, the area under the receiver operating characteristic curve about UI/UCr ratio (0.737) was the biggest within the iodine metabolism biomarkers. The UI/UCr ratio may be used for iodine nutrition evaluation in surgically treated patients with thyroid disease.

Direct evidence for coastal iodine particles from Laminaria macroalgae - linkage to emissions of molecular iodine

NASA Astrophysics Data System (ADS)

McFiggans, G.; Coe, H.; Burgess, R.; Allan, J.; Cubison, M.; Rami Alfarra, M.; Saunders, R.; Saiz-Lopez, A.; Plane, J. M. C.; Wevill, D.; Carpenter, L.; Rickard, A. R.; Monks, P. S.

2004-02-01

Renewal of ultrafine aerosols in the marine boundary layer may lead to repopulation of the marine distribution and ultimately determine the concentration of cloud condensation nuclei (CCN). Thus the formation of nanometre-scale particles can lead to enhanced scattering of incoming radiation and a net cooling of the atmosphere. The recent demonstration of the chamber formation of new particles from the photolytic production of condensable iodine-containing compounds from diiodomethane (CH2I2), (O'Dowd et al., 2002; Kolb, 2002; Jimenez et al., 2003a; Burkholder and Ravishankara, 2003), provides an additional mechanism to the gas-to-particle conversion of sulphuric acid formed in the photo-oxidation of dimethylsulphide for marine aerosol repopulation. CH2I2 is emitted from seaweeds (Carpenter et al., 1999, 2000) and has been suggested as an initiator of particle formation. We demonstrate here for the first time that ultrafine iodine-containing particles are produced by intertidal macroalgae exposed to ambient levels of ozone. The particle composition is very similar both to those formed in the chamber photo-oxidation of diiodomethane and in the oxidation of molecular iodine by ozone. The particles formed in all three systems are similarly aspherical and behave alike when exposed to increased humidity environments. Direct coastal boundary layer observations of molecular iodine, ultrafine particle production and iodocarbons are reported. Using a newly measured molecular iodine photolysis rate, it is shown that, if atomic iodine is involved in the observed particle bursts, it is of the order of at least 1000 times more likely to result from molecular iodine photolysis than diiodomethane photolysis. A hypothesis for molecular iodine release from intertidal macroalgae is presented and the potential importance of macroalgal iodine particles in their contribution to CCN and global radiative forcing are discussed.

Influence of light-induced conical intersection on the photodissociation dynamics of D2(+) starting from individual vibrational levels.

PubMed

Halász, Gábor J; Csehi, András; Vibók, Ágnes; Cederbaum, Lorenz S

2014-12-26

Previous works have shown that dressing of diatomic molecules by standing or by running laser waves gives rise to the appearance of so-called light-induced conical intersections (LICIs). Because of the strong nonadiabatic couplings, the existence of such LICIs may significantly change the dynamical properties of a molecular system. In our former paper (J. Phys. Chem. A 2013, 117, 8528), the photodissociation dynamics of the D(2)(+) molecule were studied in the LICI framework starting the initial vibrational nuclear wave packet from the superposition of all the vibrational states initially produced by ionizing D(2). The present work complements our previous investigation by letting the initial nuclear wave packets start from different individual vibrational levels of D(2)(+), in particular, above the energy of the LICI. The kinetic energy release spectra, the total dissociation probabilities, and the angular distributions of the photofragments are calculated and discussed. An interesting phenomenon has been found in the spectra of the photofragments. Applying the light-induced adiabatic picture supported by LICI, explanations are given for the unexpected structure of the spectra.

Near-UV Photodissociation of Tryptic Peptide Cation Radicals. Scope and Effects of Amino Acid Residues and Radical Sites

NASA Astrophysics Data System (ADS)

Nguyen, Huong T. H.; Tureček, František

2017-07-01

Peptide cation-radical fragment ions of the z-type, [●AXAR+], [●AXAK+], and [●XAR+], where X = A, C, D, E, F, G, H, K, L, M, N, P, Y, and W, were generated by electron transfer dissociation of peptide dications and investigated by MS3-near-ultraviolet photodissociation (UVPD) at 355 nm. Laser-pulse dependence measurements indicated that the ion populations were homogeneous for most X residues except phenylalanine. UVPD resulted in dissociations of backbone CO-NH bonds that were accompanied by hydrogen atom transfer, producing fragment ions of the [yn]+ type. Compared with collision-induced dissociation, UVPD yielded less side-chain dissociations even for residues that are sensitive to radical-induced side-chain bond cleavages. The backbone dissociations are triggered by transitions to second ( B) excited electronic states in the peptide ion R-CH●-CONH- chromophores that are resonant with the 355-nm photon energy. Electron promotion increases the polarity of the B excited states, R-CH+-C●(O-)NH-, and steers the reaction to proceed by transfer of protons from proximate acidic Cα and amide nitrogen positions.

Photodissociation dynamics of bromoiodomethane from the first and second absorption bands. A combined velocity map and slice imaging study.

PubMed

Marggi Poullain, Sonia; Chicharro, David V; Navarro, Eduardo; Rubio-Lago, Luis; González-Vázquez, Jesús; Bañares, Luis

2018-01-31

The photodissociation dynamics of bromoiodomethane (CH 2 BrI) have been investigated at the maximum of the first A and second A' absorption bands, at 266 and 210 nm excitation wavelengths, respectively, using velocity map and slice imaging techniques in combination with a probe detection of both iodine and bromine fragments, I( 2 P 3/2 ), I*( 2 P 1/2 ), Br( 2 P 3/2 ) and Br*( 2 P 1/2 ) via (2 + 1) resonance enhanced multiphoton ionization. Experimental results, i.e. translational energy and angular distributions, are reported and discussed in conjunction with high level ab initio calculations of potential energy curves and absorption spectra. The results indicate that in the A-band, direct dissociation through the 5A' excited state leads to the I( 2 P 3/2 ) channel while I*( 2 P 1/2 ) atoms are produced via the 5A' → 4A'/4A'' nonadiabatic crossing. The presence of Br and Br* fragments upon excitation to the A-band is attributed to indirect dissociation via a curve crossing between the 5A' with upper excited states such as the 9A'. The A'-band is characterized by a strong photoselectivity leading exclusively to the Br( 2 P 3/2 ) and Br*( 2 P 1/2 ) channels, which are likely produced by dissociation through the 9A' excited state. Avoided crossings between several excited states from both the A and A' bands entangle however the possible reaction pathways.

Massive isotopic effect in vacuum UV photodissociation of N2 and implications for meteorite data

PubMed Central

Chakraborty, Subrata; Muskatel, B. H.; Jackson, Teresa L.; Ahmed, Musahid; Levine, R. D.; Thiemens, Mark H.

2014-01-01

Nitrogen isotopic distributions in the solar system extend across an enormous range, from −400‰, in the solar wind and Jovian atmosphere, to about 5,000‰ in organic matter in carbonaceous chondrites. Distributions such as these require complex processing of nitrogen reservoirs and extraordinary isotope effects. While theoretical models invoke ion-neutral exchange reactions outside the protoplanetary disk and photochemical self-shielding on the disk surface to explain the variations, there are no experiments to substantiate these models. Experimental results of N2 photolysis at vacuum UV wavelengths in the presence of hydrogen are presented here, which show a wide range of enriched δ15N values from 648‰ to 13,412‰ in product NH3, depending upon photodissociation wavelength. The measured enrichment range in photodissociation of N2, plausibly explains the range of δ15N in extraterrestrial materials. This study suggests the importance of photochemical processing of the nitrogen reservoirs within the solar nebula. PMID:25267643

Efficiency of ablative loading of material upon the fast-electron transfer of absorbed laser energy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gus'kov, Sergei Yu; Kasperczuk, A; Pisarczyk, T

2006-05-31

We present the results of experiments on the short-term irradiation of a solid material by a laser beam. The data testify to a rise in efficiency of the energy transfer from the laser pulse to a shock wave due to the fast-electron energy transfer. The experiments were performed with massive aluminium targets on the PALS iodine laser, whose pulse duration (0.4 ns) was much shorter than the time of shock decay and crater formation in the target (50-200 ns). The irradiation experiments were carried out using the fundamental laser harmonic (1.315 {mu}m) with an energy of 360 J. The greatermore » part of the experiments were performed for the radiation intensity exceeding 10{sup 15} W cm{sup -2}, which corresponded to the efficient generation of fast electrons under the conditions where the relatively long-wavelength iodine-laser radiation was employed. The irradiation intensity was varied by varying the laser beam radius for a specified pulse energy. (interaction of laser radiation with matter. laser plasma)« less

Ultraviolet, Infrared, and High-Low Energy Photodissociation of Post-Translationally Modified Peptides

NASA Astrophysics Data System (ADS)

Halim, Mohammad A.; MacAleese, Luke; Lemoine, Jérôme; Antoine, Rodolphe; Dugourd, Philippe; Girod, Marion

2018-02-01

Mass spectrometry-based methods have made significant progress in characterizing post-translational modifications in peptides and proteins; however, certain aspects regarding fragmentation methods must still be improved. A good technique is expected to provide excellent sequence information, locate PTM sites, and retain the labile PTM groups. To address these issues, we investigate 10.6 μm IRMPD, 213 nm UVPD, and combined UV and IR photodissociation, known as HiLoPD (high-low photodissociation), for phospho-, sulfo-, and glyco-peptide cations. IRMPD shows excellent backbone fragmentation and produces equal numbers of N- and C-terminal ions. The results reveal that 213 nm UVPD and HiLoPD methods can provide diverse backbone fragmentation producing a/x, b/y, and c/z ions with excellent sequence coverage, locate PTM sites, and offer reasonable retention efficiency for phospho- and glyco-peptides. Excellent sequence coverage is achieved for sulfo-peptides and the position of the SO3 group can be pinpointed; however, widespread SO3 losses are detected irrespective of the methods used herein. Based on the overall performance achieved, we believe that 213 nm UVPD and HiLoPD can serve as alternative options to collision activation and electron transfer dissociations for phospho- and glyco-proteomics.

New insights into photodissociation dynamics of cyclobutanone from the AIMS dynamic simulation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu, Lihong; Fang, Wei-Hai, E-mail: fangwh@bnu.edu.cn

2016-04-14

In this work, the combined electronic structure calculations and non-adiabatic dynamics simulations were performed for understanding mechanistic photodissociation of cyclobutanone at ∼248 nm. Besides the stationary and intersection structures reported before, two new conical intersections between the ground (S{sub 0}) and the first excited singlet (S{sub 1}) states were determined in the present study, which were confirmed to be the new S{sub 1} → S{sub 0} funnels by the ab initio multiple spawning dynamic simulation, giving rise to products in the S{sub 0} state selectively. The time evolution of the S{sub 1} electronic population was fitted with the pure exponentialmore » formulae, from which the S{sub 1} lifetime was estimated to be 484.0 fs. The time constant for the S{sub 1} α-cleavage is calculated to be 176.6 fs, which is based on the present dynamics simulation. As a result of the ultrafast S{sub 1} processes, the statistical distribution of the excess energies is prevented in the S{sub 1} state. The S{sub 1} dynamic effect (the nonergodic behavior) was predicted to be an important factor that is responsible for the wavelength dependence of the branching ratio of photodissociation products, which will be discussed in detail.« less

Development of safe infrared gas lasers

NASA Astrophysics Data System (ADS)

Mainuddin; Singhal, Gaurav; Tyagi, R. K.; Maini, A. K.

2013-04-01

Infrared gas lasers find application in numerous civil and military areas. Such lasers are therefore being developed at different institutions around the world. However, the development of chemical infrared gas lasers such as chemical oxygen iodine lasers (COIL) involves the use of several hazardous chemicals. In order to exploit full potential of these lasers, one must take diligent care of the safety issues associated with the handling of these chemicals and the involved processes. The present paper discusses the safety aspects to be taken into account in the development of these infrared gas lasers including various detection sensors working in conjunction with a customized data acquisition system loaded with safety interlocks for safe operation. The developed safety schemes may also be implemented for CO2 gas dynamic laser (GDL) and hydrogen fluoride-deuterium fluoride (HF-DF) Laser.

Mineral resource of the month: iodine

USGS Publications Warehouse

Polyak, Désirée E.

2009-01-01

The article focuses on iodine, its benefits and adverse effects, and its production and consumption. It states that iodine is essential to humans for it produces thyroid hormones to nourish thyroid glands but excessive intake could cause goiter, hyperthyroidism or hypothyroidism. U.S. laws require salt iodization to help prevent diseases. Chile and Japan are the world's leading iodine producer while in the U.S. iodine is mined from deep well brines in northern Oklahoma.

Iodine nutrition status in lactating mothers residing in countries with mandatory and voluntary iodine fortification programs: an updated systematic review.

PubMed

Nazeri, Pantea; Mirmiran, Parvin; Shiva, Niloofar; Mehrabi, Yadollah; Mojarrad, Mehdi; Azizi, Fereidoun

2015-06-01

The aim of this review is to assess data available on iodine nutrition status in lactating mothers residing in countries with mandatory and voluntary iodine fortification programs and/or iodine supplementation. A systematic review was conducted by searching articles published between 1964 and 2013 in Pub Med, ISI Web, and Cochrane Library using iodine nutrition, lactation, iodine supplementation, and iodine fortification as keywords for titles and/or abstracts. Relevant articles were included if they reported urinary iodine concentration (UIC) in lactating mothers and, if determined, the type of iodine fortification program and/or iodine supplementation. Forty-two studies met the inclusion criteria. Among these, 21 studies assessed lactating mothers in countries with a mandatory iodine fortification program, 17 studies were from countries with voluntary and/or without iodine fortification programs, and four studies assessed iodine nutrition status in lactating mothers undergoing iodine supplementation. Among countries with mandatory iodine fortification programs, the range of salt iodization level in lactating mothers with a UIC <100 μg/L was between 8 and 40 ppm, whereas among lactating mothers with UIC >100 μg/L, it was between 15 and 60 ppm. Levels of UIC <100 μg/L were observed among lactating women in India, Denmark, Mali, New Zealand, Australia, Slovakia, Sudan, and Turkey, whereas in countries such as Chile, Iran, Mongolia, New Guinea, and Nigeria, the median or mean of UIC was >100 μg/L. There was a median or mean UIC <100 μg/L in nearly all lactating mothers residing in countries where implementation of universal salt iodization program was voluntary, including Switzerland, Australia, New Zealand, Ireland, and Germany. However, in some countries with voluntary iodine fortification programs, such as the United States, Spain, and Japan, a mean or median UIC of >100 μg/L has been reported. Although universal salt iodization is still the

Photodissociation of aligned CH3I and C6H3F2I molecules probed with time-resolved Coulomb explosion imaging by site-selective extreme ultraviolet ionization

PubMed Central

Amini, Kasra; Savelyev, Evgeny; Brauße, Felix; Berrah, Nora; Bomme, Cédric; Brouard, Mark; Burt, Michael; Christensen, Lauge; Düsterer, Stefan; Erk, Benjamin; Höppner, Hauke; Kierspel, Thomas; Krecinic, Faruk; Lauer, Alexandra; Lee, Jason W. L.; Müller, Maria; Müller, Erland; Mullins, Terence; Redlin, Harald; Schirmel, Nora; Thøgersen, Jan; Techert, Simone; Toleikis, Sven; Treusch, Rolf; Trippel, Sebastian; Ulmer, Anatoli; Vallance, Claire; Wiese, Joss; Johnsson, Per; Küpper, Jochen; Rudenko, Artem; Rouzée, Arnaud; Stapelfeldt, Henrik; Rolles, Daniel; Boll, Rebecca

2018-01-01

We explore time-resolved Coulomb explosion induced by intense, extreme ultraviolet (XUV) femtosecond pulses from a free-electron laser as a method to image photo-induced molecular dynamics in two molecules, iodomethane and 2,6-difluoroiodobenzene. At an excitation wavelength of 267 nm, the dominant reaction pathway in both molecules is neutral dissociation via cleavage of the carbon–iodine bond. This allows investigating the influence of the molecular environment on the absorption of an intense, femtosecond XUV pulse and the subsequent Coulomb explosion process. We find that the XUV probe pulse induces local inner-shell ionization of atomic iodine in dissociating iodomethane, in contrast to non-selective ionization of all photofragments in difluoroiodobenzene. The results reveal evidence of electron transfer from methyl and phenyl moieties to a multiply charged iodine ion. In addition, indications for ultrafast charge rearrangement on the phenyl radical are found, suggesting that time-resolved Coulomb explosion imaging is sensitive to the localization of charge in extended molecules. PMID:29430482

Photodissociation of aligned CH3I and C6H3F2I molecules probed with time-resolved Coulomb explosion imaging by site-selective extreme ultraviolet ionization.

PubMed

Amini, Kasra; Savelyev, Evgeny; Brauße, Felix; Berrah, Nora; Bomme, Cédric; Brouard, Mark; Burt, Michael; Christensen, Lauge; Düsterer, Stefan; Erk, Benjamin; Höppner, Hauke; Kierspel, Thomas; Krecinic, Faruk; Lauer, Alexandra; Lee, Jason W L; Müller, Maria; Müller, Erland; Mullins, Terence; Redlin, Harald; Schirmel, Nora; Thøgersen, Jan; Techert, Simone; Toleikis, Sven; Treusch, Rolf; Trippel, Sebastian; Ulmer, Anatoli; Vallance, Claire; Wiese, Joss; Johnsson, Per; Küpper, Jochen; Rudenko, Artem; Rouzée, Arnaud; Stapelfeldt, Henrik; Rolles, Daniel; Boll, Rebecca

2018-01-01

We explore time-resolved Coulomb explosion induced by intense, extreme ultraviolet (XUV) femtosecond pulses from a free-electron laser as a method to image photo-induced molecular dynamics in two molecules, iodomethane and 2,6-difluoroiodobenzene. At an excitation wavelength of 267 nm, the dominant reaction pathway in both molecules is neutral dissociation via cleavage of the carbon-iodine bond. This allows investigating the influence of the molecular environment on the absorption of an intense, femtosecond XUV pulse and the subsequent Coulomb explosion process. We find that the XUV probe pulse induces local inner-shell ionization of atomic iodine in dissociating iodomethane, in contrast to non-selective ionization of all photofragments in difluoroiodobenzene. The results reveal evidence of electron transfer from methyl and phenyl moieties to a multiply charged iodine ion. In addition, indications for ultrafast charge rearrangement on the phenyl radical are found, suggesting that time-resolved Coulomb explosion imaging is sensitive to the localization of charge in extended molecules.

Longitudinal trends in thyroid function in relation to iodine intake: ongoing changes of thyroid function despite adequate current iodine status.

PubMed

van de Ven, Annenienke C; Netea-Maier, Romana T; Ross, H Alec; van Herwaarden, Teun A E; Holewijn, Suzanne; de Graaf, Jacqueline; Kiemeney, Bart L A; van Tienoven, Doorlène; Wetzels, Jack F M; Smit, Johannes W; Sweep, Fred C G J; Hermus, Ad R M M; den Heijer, Martin

2014-01-01

Several cross-sectional studies on populations with iodine deficiency showed that TSH-levels are negatively associated with age, while in populations with high iodine intake TSH is positively associated with age. The question is whether such an age-thyroid function relation is an ongoing process apparent also in longitudinal studies and whether it reflects an actual iodine deficiency or an iodine insufficiency in the past. In an area with a borderline iodine status in the past, we studied 980 participants of the Nijmegen Biomedical Study. We measured serum TSH, free thyroxine (FT₄), total triiodothyronine (T₃), peroxidase antibodies, and the urine iodine and creatinine concentration 4 years after our initial survey of thyroid function, in which we reported a negative association between TSH and age. within 4 years, TSH decreased by 5.4% (95% ci 2.58.3%) and FT₄ increased by 3.7% (95% ci 2.94.6%). median urinary iodine concentration was 130 μg/l. estimated 24-h iodine excretion was not associated with TSH, T₃, change of TSH, or FT₄ over time or with the presence of antibodies against thyroid peroxidase. Only FT₄ appeared to be somewhat higher at lower urine iodine levels: a 1.01% (95% CI 0.17-1.84%) higher FT₄ for each lower iodine quintile. In this longitudinal study, we found an ongoing decrease in TSH and increase in FT₄ in a previously iodine insufficient population, despite the adequate iodine status at present. This suggests that low iodine intake at young age leads to thyroid autonomy (and a tendency to hyperthyroidism) that persists despite normal iodine intake later in life.

Photoacoustic Studies on Iodine.

NASA Astrophysics Data System (ADS)

Bhan, Avtar N.

A photoacoustic cavity was constructed which employs a temperature-controlled cylindrical cavity with optical windows at either end. It was operated in the lowest longitudinal mode using a small electret microphone for detecting the acoustic signal and a photomultiplier tube for detecting the optical signal. Molecular Iodine was used as the specimen gas and argon as the buffer gas. The photoacoustic characteristics of the system were studied. Iodine molecules, excited periodically by intensity modulated optical radiation (xenon discharge), de-excited by non-radiative processes which result in pressure waves having the same modulation frequency as that of the light. These pressure waves are detected as acoustical pulses by the microphone situated in the wall of the cavity. Studies were conducted for different pressures of buffer gas (100 torr to 800 torr) at several different Iodine pressures in the range between 0.3 and 1 torr. The longitudinal mode of excitation provides an opportunity to compare the response of the cavity under acoustical excitation with that under optical excitation. The relevant parameters in the investigation were: Q, the quality factor of the cavity; the resonant frequency, partial pressures of argon and Iodine; temperature; and the signal amplitude. It was found that the Q of the cavity was well -behaved following the theoretically predicted dependence on SQRT.(P and on T('- 3/4). The absorption coefficient of Iodine determined photometrically, increased with increasing argon pressure up to a limiting value of pressure that depended on Iodine concentration. The photoacoustic signal showed a similar increase with increasing argon pressure. This signal reached a limiting value at a pressure which corresponded closely with that found optically. This is taken to indicate that the extinction coefficient of Iodine in argon, at the level of dilution used in these studies, depends on the argon pressure. A method was developed for measuring the

Multiple product pathways in photodissociation of nitromethane at 213 nm

NASA Astrophysics Data System (ADS)

Sumida, Masataka; Kohge, Yasunori; Yamasaki, Katsuyoshi; Kohguchi, Hiroshi

2016-02-01

In this paper, we present a photodissociation dynamics study of nitromethane at 213 nm in the π → π* transition. Resonantly enhanced multiphoton ionization spectroscopy and ion-imaging were applied to measure the internal state distributions and state-resolved scattering distributions of the CH3, NO(X 2Π, A 2Σ+), and O(3PJ) photofragments. The rotationally state-resolved scattering distribution of the CH3 fragment showed two velocity components, of which the slower one decreased the relative intensity as the rotational and vibrational excitations. The translational energy distribution of the faster CH3 fragment indicated the production of the NO2 counter-product in the electronic excited state, wherein 1 2B2 was the most probable. The NO(v = 0) fragment exhibited a bimodal translational energy distribution, whereas the NO(v = 1 and 2) fragment exhibited a single translational energy component with a relatively larger internal energy. The translational energy of a portion of the O(3PJ) photofragment was found to be higher than the one-photon dissociation threshold, indicating the two-photon process involved. The NO(A 2Σ+) fragment, which was detected by ionization spectroscopy via the Rydberg ←A 2Σ+ transition, also required two-photon energy. These experimental data corroborate the existence of competing photodissociation product pathways, CH3 + NO2,CH3 + NO + O,CH3O + NO, and CH3NO + O, following the π → π* transition. The origins of the observed photofragments are discussed in this report along with recent theoretical studies and previous dynamics experiments performed at 193 nm.

Multiple product pathways in photodissociation of nitromethane at 213 nm.

PubMed

Sumida, Masataka; Kohge, Yasunori; Yamasaki, Katsuyoshi; Kohguchi, Hiroshi

2016-02-14

In this paper, we present a photodissociation dynamics study of nitromethane at 213 nm in the π → π(*) transition. Resonantly enhanced multiphoton ionization spectroscopy and ion-imaging were applied to measure the internal state distributions and state-resolved scattering distributions of the CH3, NO(X (2)Π, A (2)Σ(+)), and O((3)PJ) photofragments. The rotationally state-resolved scattering distribution of the CH3 fragment showed two velocity components, of which the slower one decreased the relative intensity as the rotational and vibrational excitations. The translational energy distribution of the faster CH3 fragment indicated the production of the NO2 counter-product in the electronic excited state, wherein 1 (2)B2 was the most probable. The NO(v = 0) fragment exhibited a bimodal translational energy distribution, whereas the NO(v = 1 and 2) fragment exhibited a single translational energy component with a relatively larger internal energy. The translational energy of a portion of the O((3)PJ) photofragment was found to be higher than the one-photon dissociation threshold, indicating the two-photon process involved. The NO(A (2)Σ(+)) fragment, which was detected by ionization spectroscopy via the Rydberg ← A (2)Σ(+) transition, also required two-photon energy. These experimental data corroborate the existence of competing photodissociation product pathways, CH3 + NO2,CH3 + NO + O,CH3O + NO, and CH3NO + O, following the π → π(*) transition. The origins of the observed photofragments are discussed in this report along with recent theoretical studies and previous dynamics experiments performed at 193 nm.

Iodine nutritional status in Asturian schoolchildren.

PubMed

Riestra Fernández, María; Menéndez Torre, Edelmiro; Díaz Cadórniga, Francisco; Fernández Fernández, Juan Carlos; Delgado Álvarez, Elías

2017-11-01

Iodine deficiency is a public health problem, and iodine nutritional status should therefore be regularly measured. To ascertain iodine nutritional status in Asturias and its relation to use of iodized salt and to other sociodemographic and nutritional parameters. A descriptive, observational study was conducted in a random sample of schoolchildren aged 5 to 14 years, in whom urinary iodine levels were measured by high-performance liquid chromatography. Families completed a survey on use of iodized salt, consumption of dairy products and fish, and sociodemographic data. The study sample consisted of 705 schoolchildren (51.1% females) with a mean age of 9.9 years (SD 2.6). In a total of 620 valid measurements, mean urinary iodine level was 204.1 μg/L (SD 120.6), while the median value was 180.7 μg/L (P 25 -P 75 : 124-252.3 μg/L, interquartile range 128.3 μg/L). Urinary iodine levels were <100 μg/L in 16.6% of children, and very low (<20 μg/L) in 0.2%. Iodized salt was used in 69.3% of all households, and in all school canteens. Consumption of dairy products was significantly associated to urinary iodine levels (P<.0005). Iodine nutrition of Asturian schoolchildren is adequate, although the target of use of iodized salt in 90% of households is still far away. Adequate iodine nutrition may be due to other sources, such as dairy products. Public health campaigns are required to promote iodized salt consumption. Regular assessment of iodine nutritional status is also needed. Copyright © 2017 SEEN y SED. Publicado por Elsevier España, S.L.U. All rights reserved.

Electronic spectroscopy and photodissociation dynamics of Co(2+)-methanol clusters: Co2+ (CH3OH)n (n = 4-7).

PubMed

Thompson, Christopher J; Faherty, Kieron P; Stringer, Kay L; Metz, Ricardo B

2005-03-07

Solvated cluster ions Co2+ (CH3OH)n (n = 4-7) have been produced by electrospray and studied using photofragment spectroscopy. There are notable differences between the photodissociation spectra of these complexes and the analogous water complexes. Co2+ (CH3OH)6 absorbs significantly more strongly than Co2+ (H2O)6. The photodissociation spectra of Co2+ (CH3OH)n (n = 4, 5 and 6) are very similar, which suggests that they share the Co2+ (CH3OH)4 chromophore, with additional solvent molecules in the second shell. In contrast, our earlier studies indicate that Co2+ (H2O)6 is six coordinate, and its spectrum is significantly different from that of Co2+ (H2O)4. The larger clusters Co2+ (CH3OH)n (n = 5-7) dissociate by simple loss of one or more solvent molecules. Larger clusters tend to lose more solvent molecules, especially at higher photon energies. As with the corresponding water cluster, Co2+ (CH3OH)4 photodissociates by proton transfer through a salt-bridge intermediate. This is accompanied by a modest kinetic energy release of 170 kJ mol(-1) and occurs with a lifetime of 145 ns.

Stabilized diode seed laser for flight and space-based remote lidar sensing applications

NASA Astrophysics Data System (ADS)

McNeil, Shirley; Pandit, Pushkar; Battle, Philip; Rudd, Joe; Hovis, Floyd

2017-08-01

AdvR, through support of the NASA SBIR program, has developed fiber-based components and sub-systems that are routinely used on NASA's airborne missions, and is now developing an environmentally hardened, diode-based, locked wavelength, seed laser for future space-based high spectral resolution lidar applications. The seed laser source utilizes a fiber-coupled diode laser, a fiber-coupled, calibrated iodine reference module to provide an absolute wavelength reference, and an integrated, dual-element, nonlinear optical waveguide component for second harmonic generation, spectral formatting and wavelength locking. The diode laser operates over a range close to 1064.5 nm, provides for stabilization of the seed to the desired iodine transition and allows for a highly-efficient, fully-integrated seed source that is well-suited for use in airborne and space-based environments. A summary of component level environmental testing and spectral purity measurements with a seeded Nd:YAG laser will be presented. A direct-diode, wavelength-locked seed laser will reduce the overall size weight and power (SWaP) requirements of the laser transmitter, thus directly addressing the need for developing compact, efficient, lidar component technologies for use in airborne and space-based environments.

Sensitive monitoring of iodine species in sea water using capillary electrophoresis: vertical profiles of dissolved iodine in the Pacific Ocean.

PubMed

Huang, Zhuo; Ito, Kazuaki; Morita, Isamu; Yokota, Kuriko; Fukushi, Keiichi; Timerbaev, Andrei R; Watanabe, Shuichi; Hirokawa, Takeshi

2005-08-01

Using a novel high-sensitivity capillary electrophoretic method, vertical distributions of iodate, iodide, total inorganic iodine, dissolved organic iodine and total iodine in the North Pacific Ocean (0-5500 m) were determined without any sample pre-treatment other than UV irradiation before total iodine analysis. An extensive set of data demonstrated that the iodine behaviour in the ocean water collected during a cruise in the North Pacific Ocean in February-March 2003 was not conservative but correlated with variations in concentrations of dissolved oxygen and nutrient elements such as silicon, nitrogen and phosphorus. This suggests that the vertical distribution of iodine is associated with biological activities. The dissolved organic iodine was found in the euphotic zone in accord with observations elsewhere in the oceans. The vertical profile of dissolved organic iodine also appears to be related to biogeochemical activity. The concentrations of all measured iodine species vary noticeably above 1000 m but only minor latitudinal changes occur below 1000 m and slight vertical alterations can be observed below 2400 m. These findings are thought to reflect the stratification of nutrients and iodine species with different biological activities in the water column.

The Effect of Povidone-Iodine (Betadine) on Serum Protein-Bound Iodine, When Used as a Surgical Preparation on Intact Skin

PubMed Central

Higgins, H. P.; Hawks, G. H.; O'Sullivan, M.; Shaw, M.

1964-01-01

A study was undertaken to determine whether the use of povidone-iodine (Betadine) as a skin disinfectant prior to surgery would affect the protein-bound iodine (PBI) and so invalidate this parameter of thyroid function. Ninety-seven consecutive patients were chosen who had no thyroid disease and who had not recently been exposed to iodine in any form. Their serum PBI levels were determined before and after a wide variety of surgical operations. Povidone-iodine was used as a skin disinfectant in the operating room in all cases. Care was taken to avoid contact of the povidone-iodine with the mucous membranes. No significant change in the protein-bound iodine could be detected and it was concluded that there could be no objection to the use of povidone-iodine on the ground of its possible effect on the protein-bound iodine. PMID:14158542

Immobilization of iodine in concrete

DOEpatents

Clark, Walter E.; Thompson, Clarence T.

1977-04-12

A method for immobilizing fission product radioactive iodine recovered from irradiated nuclear fuel comprises combining material comprising water, Portland cement and about 3-20 wt. % iodine as Ba(IO.sub.3).sub.2 to provide a fluid mixture and allowing the fluid mixture to harden, said Ba(IO.sub.3).sub.2 comprising said radioactive iodine. An article for solid waste disposal comprises concrete prepared by this method. BACKGROUND OF THE INVENTION This invention was made in the course of, or under a contract with the Energy Research and Development Administration. It relates in general to reactor waste solidification and more specifically to the immobilization of fission product radioactive iodine recovered from irradiated nuclear fuel for underground storage.

Comparison of breast-milk iodine concentration of lactating women in Australia pre and post mandatory iodine fortification.

PubMed

Huynh, Dao; Condo, Dominique; Gibson, Robert; Makrides, Maria; Muhlhausler, Beverly; Zhou, Shao Jia

2017-01-01

To compare the breast-milk iodine concentrations (BMIC) of lactating women before and after the mandatory iodine fortification of bread in Australia in 2009. Cross-sectional study. Breast milk samples were collected from two cohorts of women in South Australia within 7 d of delivery to determine BMIC. The percentage of samples with iodine concentration below 100 µg/l, a level considered adequate for breast-fed infants, was calculated. Sociodemographic information and intake of dietary supplements were obtained from all women. The breast milk samples were collected between 2006 and 2007 in the pre-fortification cohort and between 2012 and 2013 in the post-fortification cohort. The median (interquartile range) BMIC was higher in the post-fortification samples compared with samples collected in the pre-fortification period (187 (130-276) v. 103 (73-156) µg/l; P<0·05). Overall, the percentage of women with BMIC <100 µg/l was lower in the post-fortification cohort than in the pre-fortification cohort (13 v. 49 %; P<0·01). The percentage of women with BMIC <100 µg/l in the post-fortification cohort was lower among women who took iodine supplements in pregnancy (12 v. 29 %; P<0·01). Mandatory iodine fortification of bread has resulted in an increase in the iodine content of breast milk in Australian women. However, iodine supplementation may still be required in some women post-iodine fortification to reach the level of BMIC that is considered adequate to meet the iodine requirement of full-term infants.

Risk of Suboptimal Iodine Intake in Pregnant Norwegian Women

PubMed Central

Brantsæter, Anne Lise; Abel, Marianne Hope; Haugen, Margaretha; Meltzer, Helle Margrete

2013-01-01

Pregnant women and infants are exceptionally vulnerable to iodine deficiency. The aims of the present study were to estimate iodine intake, to investigate sources of iodine, to identify predictors of low or suboptimal iodine intake (defined as intakes below 100 μg/day and 150 μg/day) in a large population of pregnant Norwegian women and to evaluate iodine status in a sub-population. Iodine intake was calculated based on a validated Food Frequency Questionnaire in the Norwegian Mother and Child Cohort. The median iodine intake was 141 μg/day from food and 166 μg/day from food and supplements. Use of iodine-containing supplements was reported by 31.6%. The main source of iodine from food was dairy products, contributing 67% and 43% in non-supplement and iodine-supplement users, respectively. Of 61,904 women, 16.1% had iodine intake below 100 μg/day, 42.0% had iodine intake below 150 μg/day and only 21.7% reached the WHO/UNICEF/ICCIDD recommendation of 250 μg/day. Dietary behaviors associated with increased risk of low and suboptimal iodine intake were: no use of iodine-containing supplements and low intake of milk/yogurt, seafood and eggs. The median urinary iodine concentration measured in 119 participants (69 μg/L) confirmed insufficient iodine intake. Public health strategies are needed to improve and secure the iodine status of pregnant women in Norway. PMID:23389302

Risk of suboptimal iodine intake in pregnant Norwegian women.

PubMed

Brantsæter, Anne Lise; Abel, Marianne Hope; Haugen, Margaretha; Meltzer, Helle Margrete

2013-02-06

Pregnant women and infants are exceptionally vulnerable to iodine deficiency. The aims of the present study were to estimate iodine intake, to investigate sources of iodine, to identify predictors of low or suboptimal iodine intake (defined as intakes below 100 μg/day and 150 μg/day) in a large population of pregnant Norwegian women and to evaluate iodine status in a sub-population. Iodine intake was calculated based on a validated Food Frequency Questionnaire in the Norwegian Mother and Child Cohort. The median iodine intake was 141 μg/day from food and 166 μg/day from food and supplements. Use of iodine-containing supplements was reported by 31.6%. The main source of iodine from food was dairy products, contributing 67% and 43% in non-supplement and iodine-supplement users, respectively. Of 61,904 women, 16.1% had iodine intake below 100 μg/day, 42.0% had iodine intake below 150 μg/day and only 21.7% reached the WHO/UNICEF/ICCIDD recommendation of 250 μg/day. Dietary behaviors associated with increased risk of low and suboptimal iodine intake were: no use of iodine-containing supplements and low intake of milk/yogurt, seafood and eggs. The median urinary iodine concentration measured in 119 participants (69 μg/L) confirmed insufficient iodine intake. Public health strategies are needed to improve and secure the iodine status of pregnant women in Norway.

UV-POSIT: Web-Based Tools for Rapid and Facile Structural Interpretation of Ultraviolet Photodissociation (UVPD) Mass Spectra

NASA Astrophysics Data System (ADS)

Rosenberg, Jake; Parker, W. Ryan; Cammarata, Michael B.; Brodbelt, Jennifer S.

2018-04-01

UV-POSIT (Ultraviolet Photodissociation Online Structure Interrogation Tools) is a suite of web-based tools designed to facilitate the rapid interpretation of data from native mass spectrometry experiments making use of 193 nm ultraviolet photodissociation (UVPD). The suite includes four separate utilities which assist in the calculation of fragment ion abundances as a function of backbone cleavage sites and sequence position; the localization of charge sites in intact proteins; the calculation of hydrogen elimination propensity for a-type fragment ions; and mass-offset searching of UVPD spectra to identify unknown modifications and assess false positive fragment identifications. UV-POSIT is implemented as a Python/Flask web application hosted at http://uv-posit.cm.utexas.edu. UV-POSIT is available under the MIT license, and the source code is available at https://github.com/jarosenb/UV_POSIT. [Figure not available: see fulltext.

UV-POSIT: Web-Based Tools for Rapid and Facile Structural Interpretation of Ultraviolet Photodissociation (UVPD) Mass Spectra.

PubMed

Rosenberg, Jake; Parker, W Ryan; Cammarata, Michael B; Brodbelt, Jennifer S

2018-06-01

UV-POSIT (Ultraviolet Photodissociation Online Structure Interrogation Tools) is a suite of web-based tools designed to facilitate the rapid interpretation of data from native mass spectrometry experiments making use of 193 nm ultraviolet photodissociation (UVPD). The suite includes four separate utilities which assist in the calculation of fragment ion abundances as a function of backbone cleavage sites and sequence position; the localization of charge sites in intact proteins; the calculation of hydrogen elimination propensity for a-type fragment ions; and mass-offset searching of UVPD spectra to identify unknown modifications and assess false positive fragment identifications. UV-POSIT is implemented as a Python/Flask web application hosted at http://uv-posit.cm.utexas.edu . UV-POSIT is available under the MIT license, and the source code is available at https://github.com/jarosenb/UV_POSIT . Graphical Abstract.

Primary quantum yields of NO2 photodissociation

NASA Technical Reports Server (NTRS)

Gardner, Edward P.; Sperry, Paul D.; Calvert, Jack G.

1987-01-01

The quantum yields of formation of NO, O2, and NO2 loss are measured for NO2 vapor at low pressures (0.13-0.30 torr) irradiated at 334-405 nm wavelengths and temperature in the range 273-370 K in order to study the primary quantum efficiencies of NO2 photodecomposition. The temperature and wavelength dependences of the primary quantum efficiencies are examined. It is observed that the primary quantum efficiencies increase rapidly from near zero at 424 nm to near unity for excitation at wavelengths less than 394 nm. The theory of Pitts et al. (1964) that the energy deficiency for photodissociation of NO2 excited at wavelengths greater than 397.9 nm is due to the rotational and vibrational energy of the NO2 molecules is confirmed by the data. Values for the primary quantum yields of NO2 photodecomposition as a function of wavelength are presented.

Thyroglobulin level at week 16 of pregnancy is superior to urinary iodine concentration in revealing preconceptual and first trimester iodine supply

PubMed Central

Katko, Monika; Gazso, Andrea Anett; Hircsu, Ildiko; Bhattoa, Harjit Pal; Molnar, Zsuzsanna; Kovacs, Bela; Andrasi, David; Aranyosi, Janos; Makai, Rita; Veress, Lajos; Torok, Olga; Bodor, Miklos; Samson, Laszlo

2017-01-01

Abstract Pregnant women are prone to iodine deficiency due to the increased need for iodine during gestation. Progress has recently occurred in establishing serum thyroglobulin (Tg) as an iodine status biomarker, but there is no accepted reference range for iodine sufficiency during pregnancy. An observational study was conducted in 164 pregnant women. At week 16 of gestation urinary iodine concentration (UIC), serum Tg, and thyroid functions were measured, and information on the type of iodine supplementation and smoking were recorded. The parameters of those who started iodine supplementation (≥150 μg/day) at least 4 weeks before pregnancy (n = 27), who started at the detection of pregnancy (n = 51), and who had no iodine supplementation (n = 74) were compared. Sufficient iodine supply was found in the studied population based on median UIC (162 μg/L). Iodine supplementation ≥150 μg/day resulted in higher median UIC regardless of its duration (nonusers: 130 μg/L vs. prepregnancy iodine starters: 240 μg/L, and pregnancy iodine starters: 205 μg/L, p < .001, and p = .023, respectively). Median Tg value of pregnancy starters was identical to that of nonusers (14.5 vs. 14.6 μg/L), whereas prepregnancy starters had lower median Tg (9.1 μg/L, p = .018). Serum Tg concentration at week 16 of pregnancy showed negative relationship (p = .010) with duration of iodine supplementation and positive relationship (p = .008) with smoking, a known interfering factor of iodine metabolism, by multiple regression analysis. Serum Tg at week 16 of pregnancy may be a promising biomarker of preconceptual and first trimester maternal iodine status, the critical early phase of foetal brain development. PMID:28593684

Effect of iodine disinfection products on higher plants

NASA Technical Reports Server (NTRS)

Janik, D.; Macler, B.; Macelroy, R. D.; Thorstenson, Y.; Sauer, R.

1989-01-01

Iodine is used to disinfect potable water on United States spacecraft. Iodinated potable water will likely be used to grow plants in space. Little is known about the effects of iodine disinfection products on plants. Seeds of select higher plants were germinated in water iodinated using the Shuttle Microbial Check Valve, and water to which measured amounts of iodine was added. Percent germination was decreased in seeds of most species germinated in iodinated water. Beans were most affected. Germination rates, determined from germination half-times, were decreased for beans germinated in iodinated water, and water to which iodide was added. Development was retarded and rootlets were conspicuously absent in bean and several other plant species germinated in iodinated water. Iodide alone did not elicit these responses. Clearly iodine disinfection products can affect higher plants. These effects must be carefully considered for plant experimentation and cultivation in space, and in design and testing of closed environmental life support systems.

The Impact of Carrot Enriched in Iodine through Soil Fertilization on Iodine Concentration and Selected Biochemical Parameters in Wistar Rats.

PubMed

Piątkowska, Ewa; Kopeć, Aneta; Bieżanowska-Kopeć, Renata; Pysz, Mirosław; Kapusta-Duch, Joanna; Koronowicz, Aneta Agnieszka; Smoleń, Sylwester; Skoczylas, Łukasz; Ledwożyw-Smoleń, Iwona; Rakoczy, Roksana; Maślak, Edyta

2016-01-01

Iodine is one of the trace elements which are essential for mammalian life. The major objective of iodine biofortification of plants is to obtain food rich in this trace element, which may increase its consumption by various populations. Additionally, it may reduce the risk of iodine deficiency diseases. In this research for the first time we have assessed the bioavailability of iodine from raw or cooked carrot biofortified with this trace element on iodine concentration in selected tissues and various biochemical parameters as well as mRNA expression of some genes involved in iodine metabolism in Wistar rats. Statistically, a significantly higher iodine level was determined in urine, faeces and selected tissues of rats fed a diet containing biofortified raw carrot as compared to a diet without iodine and a diet containing control cooked carrot. Biofortified raw carrot significantly increased triiodothyronine concentration as compared to animals from other experimental groups. The highest thyroid stimulating hormone level was determined in rats fed control cooked carrots. mRNA expression of selected genes was affected by different dietary treatment in rats' hearts. Biofortified raw and cooked carrot could be taken into account as a potential source of iodine in daily diets to prevent iodine deficiency in various populations.

The Impact of Carrot Enriched in Iodine through Soil Fertilization on Iodine Concentration and Selected Biochemical Parameters in Wistar Rats

PubMed Central

Piątkowska, Ewa; Kopeć, Aneta; Bieżanowska-Kopeć, Renata; Pysz, Mirosław; Kapusta-Duch, Joanna; Koronowicz, Aneta Agnieszka; Smoleń, Sylwester; Skoczylas, Łukasz; Ledwożyw-Smoleń, Iwona; Rakoczy, Roksana; Maślak, Edyta

2016-01-01

Iodine is one of the trace elements which are essential for mammalian life. The major objective of iodine biofortification of plants is to obtain food rich in this trace element, which may increase its consumption by various populations. Additionally, it may reduce the risk of iodine deficiency diseases. In this research for the first time we have assessed the bioavailability of iodine from raw or cooked carrot biofortified with this trace element on iodine concentration in selected tissues and various biochemical parameters as well as mRNA expression of some genes involved in iodine metabolism in Wistar rats. Statistically, a significantly higher iodine level was determined in urine, faeces and selected tissues of rats fed a diet containing biofortified raw carrot as compared to a diet without iodine and a diet containing control cooked carrot. Biofortified raw carrot significantly increased triiodothyronine concentration as compared to animals from other experimental groups. The highest thyroid stimulating hormone level was determined in rats fed control cooked carrots. mRNA expression of selected genes was affected by different dietary treatment in rats’ hearts. Biofortified raw and cooked carrot could be taken into account as a potential source of iodine in daily diets to prevent iodine deficiency in various populations. PMID:27043135

An age-specific biokinetic model for iodine

DOE Office of Scientific and Technical Information (OSTI.GOV)

Leggett, Richard Wayne

This study reviews age-specific biokinetic data for iodine in humans and extends to pre-adult ages the baseline parameter values of the author’s previously published model for systemic iodine in adult humans. Compared with the ICRP’s current age-specific model for iodine introduced in Publication 56 (1989), the present model provides a more detailed description of the behavior of iodine in the human body; predicts greater cumulative (integrated) activity in the thyroid for short-lived isotopes of iodine; predicts similar cumulative activity in the thyroid for isotopes with half-time greater than a few hours; and, for most iodine isotopes, predicts much greater cumulativemore » activity in salivary glands, stomach wall, liver, and kidneys.« less

An age-specific biokinetic model for iodine

DOE PAGES

Leggett, Richard Wayne

2017-10-26

This study reviews age-specific biokinetic data for iodine in humans and extends to pre-adult ages the baseline parameter values of the author’s previously published model for systemic iodine in adult humans. Compared with the ICRP’s current age-specific model for iodine introduced in Publication 56 (1989), the present model provides a more detailed description of the behavior of iodine in the human body; predicts greater cumulative (integrated) activity in the thyroid for short-lived isotopes of iodine; predicts similar cumulative activity in the thyroid for isotopes with half-time greater than a few hours; and, for most iodine isotopes, predicts much greater cumulativemore » activity in salivary glands, stomach wall, liver, and kidneys.« less

Iodine deficiency in pregnant women living in the South-East of the UK: the influence of diet and nutritional supplements on iodine status

PubMed Central

Bath, Sarah C.; Walter, Alan; Taylor, Andrew; Wright, John; Rayman, Margaret P.

2015-01-01

Iodine is a key component of the thyroid hormones which are crucial for brain development. Pregnant women are vulnerable to iodine deficiency because their requirement for iodine is higher than that of non-pregnant adults. Data on the iodine status of UK pregnant women are sparse and there are no such data in the South East. One hundred pregnant women were recruited to a cross-sectional study at the Royal Surrey County Hospital, Guildford, at their first-trimester visit for an ultrasound scan. Participants provided a spot-urine sample (for the measurement of urinary iodine and creatinine concentrations) and 24-hour excretion of iodine was estimated from the urinary iodine-to-creatinine ratio. Women completed a general questionnaire and a food-frequency questionnaire. The median urinary iodine concentration (85·3 μg/l) indicated that the group was iodine deficient by WHO criteria. The median values of the iodine-to-creatinine ratio (122·9 μg/g) and of the estimated 24-hr iodine excretion (151·2 μg/day) were also suggestive of iodine deficiency. Urinary iodine concentration was significantly higher in women taking an iodine-containing prenatal supplement (n=42) than in those not taking such a supplement (P<0·001). In adjusted analyses, milk intake, maternal age and iodine-containing prenatal supplement use were positively associated with estimated 24-hour urinary iodine excretion. Our finding of iodine deficiency in these women gives cause for concern. We suggest that women of childbearing age and pregnant women should be given advice on how to improve their iodine status through dietary means. A national survey of iodine status in UK pregnant women is required. PMID:24398008

The photodissociation lifetimes of the OH and OD radicals in comets

NASA Technical Reports Server (NTRS)

Singh, P. D.; Van Dishoeck, E. F.; Dalgarno, A.

1983-01-01

The photodissociation rates of OH and OD molecules due to absorption of solar radiation in the X(2)Pi-A(2)Sigma(+) electronic transition are calculated to lie between 3.5 and 6.7 x 10 to the -6th/sec for OH for heliocentric velocities between -60 and +60 km/sec and at about 4.7 x 10 to the -7th/sec for OD at 1 AU from the sun. The corresponding lifetimes, which are upper bounds to the actual lifetimes, are generally consistent with the observational cometary data.

Urinary Iodine Concentrations in Cancer Patients

PubMed Central

Kargar, Saeed; Shiryazdi, Seyed Mostafa; Atashi, Seyed Reza; Neamatzadeh, Hossein; Kamali, Mahdieh

2017-01-01

Background: It has been suggested that incidence of some cancers, especially examples in the breast and stomach may be influenced by the iodine intake. However, only few studies are available at present. Therefore, we have conducted the present assessment of iodine status in Iranian patients diagnosed with a malignancy. Materials and Methods: This cross-sectional study was conducted in 85 patients diagnosed with different types of cancer at Shahid Sadoughi Hospital, Yazd, Iran. The method used was based on the Sandell–Kolthoff reaction. Results: The median urinary iodine concentration (UIC) was 17.4 μg/L, with ≤20 μg/L indicative of severe iodine deficiency. According to the WHO/IC C IDD/UNIC EF classification, 88.1%, 7.1% and 2.4% of patients had a UIC <20 (severe), 20–49 (mild), and 50–99 μg/L (moderate), respectively. There was no statistically significant differences in UIC between men and women. Conclusion: The UIC values indicate that Iranian cancer patients were seriously iodine deficient according to WHO/UNIC EF/IC C IDD, and that this is a suitable index to assess iodine status in Iranians. Daily consumption of salt fortified with iodine or other approaches to increase intake might be effective strategies for prevention or reduction of malignancies. PMID:28441792

An assessment of the iodine status and the correlation between iodine nutrition and thyroid function during pregnancy in an iodine sufficient area.

PubMed

Amouzegar, A; Khazan, M; Hedayati, M; Azizi, F

2014-03-01

Iodine as a micronutrient is mandatory for thyroid hormone production and inadequate iodine intakes during pregnancy may result in varying degrees of hypothyroidism affecting pregnancy outcomes adversely. The aim of this study was to evaluate nutritional status and its effects on thyroid function in pregnant women during all trimesters of pregnancy. In this cohort study, we assessed a total of 203 pregnant women in the first trimester of pregnancy and followed them in the second and third trimesters. They were divided into two groups, group I with urinary iodine excretion (UIE) < 150 μg/l, and group II with UIE ≥ 150 μg/l. Serum samples from women were assayed for levels of total T4, T3, FT4I and thyroid-stimulating hormone (TSH), thyroid peroxidase antibody (TPOAb) and thyroglobulin antibody (TgAb) only once in each trimester. Urinary iodine concentration was measured three times and the median was considered as UIE in the first trimester, but it was measured only once in the second and third trimesters. The median inter quartile ranges of urinary iodine were 218 (150-276) μg/l, 160 (106-260) μg/l and 145 (88-225) μg/l in the three trimesters of pregnancy, respectively; UIE<150 was observed in 48 (24.1%), 90 (44.8%) and 103 (52.3%) of pregnant women in the three trimesters of pregnancy, respectively. The median (range) of TSH was 1.7 (0.9-2.7) mIU/l, 1.9(1.2-2.7) mIU/l and 1.8 (1.1-2.8) mIU/l in the three trimesters of pregnancy, respectively. There was no correlation between UIE, TSH, TT4, FT4I, T3 and TPOAb in the first and second trimesters, but there was a weak correlation between UIE, TSH, T3 and TgAb in the third trimester. In our cohort of pregnant women the iodine intakes were sufficient, and no correlation between urinary iodine concentration and thyroid function tests was found.

A Review: Radiographic Iodinated Contrast Media-Induced Thyroid Dysfunction

PubMed Central

Leung, Angela M.; Braverman, Lewis E.; Brent, Gregory A.; Pearce, Elizabeth N.

2015-01-01

Context: Thyroid hormone production is dependent on adequate iodine intake. Excess iodine is generally well-tolerated, but thyroid dysfunction can occur in susceptible individuals after excess iodine exposure. Radiological iodinated contrast media represent an increasingly common source of excess iodine. Objective: This review will discuss the thyroidal response after acute exposure to excess iodine; contrast iodine-induced thyroid dysfunction; risks of iodine-induced thyroid dysfunction in vulnerable populations, such as the fetus, neonate, and patients with impaired renal function; and recommendations for the assessment and treatment of contrast iodine-induced thyroid dysfunction. Methods: Data for this review were identified by searching PubMed, Google Scholar, and references from relevant articles from 1948 to 2014. Conclusions: With the increase in the use of computed tomography scans in the United States, there is increasing risk of contrast-induced thyroid dysfunction. Patients at risk of developing iodine-induced thyroid dysfunction should be closely monitored after receiving iodinated contrast media and should be treated as needed. PMID:25375985

The importance of iodine in public health.

PubMed

Lazarus, John H

2015-08-01

Iodine (I) deficiency has been known for more than a century and is known to cause cretinism at the extreme end of the spectrum but also, importantly, impaired development and neurocognition in areas of mild deficiency. The WHO has indicated that median urinary iodine of 100-199 μg/l in a population is regarded as indicative of an adequate iodine intake. The understanding of the spectrum of iodine deficiency disorders led to the formation of The International Council for the Control of Iodine Deficiency Disorders which has promulgated the use of household iodized salt and the use of such salt in food processing and manufacture. Iodine deficiency is particularly important in pregnancy as the fetus relies on maternal thyroxine (T4) exclusively during the first 14 weeks and also throughout gestation. As this hormone is critical to brain and nervous system maturation, low maternal T4 results in low child intelligence quotient. The recommendation for I intake in pregnancy is 250 μg/day to prevent fetal and child brain function impairment. During the past 25 years, the number of countries with I deficiency has reduced to 32; these still include many European developed countries. Sustainability of adequate iodine status must be achieved by continuous monitoring and where this has not been performed I deficiency has often recurred. More randomized controlled trials of iodine supplementation in pregnancy are required in mild iodine-deficient areas to inform public health strategy and subsequent government action on suitable provision of iodine to the population at risk.

Device and method for separating oxygen isotopes

DOEpatents

Rockwood, Stephen D.; Sander, Robert K.

1984-01-01

A device and method for separating oxygen isotopes with an ArF laser which produces coherent radiation at approximately 193 nm. The output of the ArF laser is filtered in natural air and applied to an irradiation cell where it preferentially photodissociates molecules of oxygen gas containing .sup.17 O or .sup.18 O oxygen nuclides. A scavenger such as O.sub.2, CO or ethylene is used to collect the preferentially dissociated oxygen atoms and recycled to produce isotopically enriched molecular oxygen gas. Other embodiments utilize an ArF laser which is narrowly tuned with a prism or diffraction grating to preferentially photodissociate desired isotopes. Similarly, desired mixtures of isotopic gas can be used as a filter to photodissociate enriched preselected isotopes of oxygen.

Global iodine nutrition: Where do we stand in 2013?

PubMed

Pearce, Elizabeth N; Andersson, Maria; Zimmermann, Michael B

2013-05-01

Dietary iodine intake is required for the production of thyroid hormone. Consequences of iodine deficiency include goiter, intellectual impairments, growth retardation, neonatal hypothyroidism, and increased pregnancy loss and infant mortality. In 1990, the United Nations World Summit for Children established the goal of eliminating iodine deficiency worldwide. Considerable progress has since been achieved, largely through programs of universal salt iodization. Approximately 70% of all households worldwide currently have access to adequately iodized salt. In 2013, as defined by a national or subnational median urinary iodine concentration of 100-299 μg/L in school-aged children, 111 countries have sufficient iodine intake. Thirty countries remain iodine-deficient; 9 are moderately deficient, 21 are mildly deficient, and none are currently considered severely iodine-deficient. Ten countries have excessive iodine intake. In North America, both the United States and Canada are generally iodine-sufficient, although recent data suggest pregnant U.S. women are mildly iodine-deficient. Emerging issues include discrepancies between urinary iodine status in pregnant women compared to school-aged children in some populations, the problem of re-emerging iodine deficiency in parts of the developed world, the importance of food industry use of iodized salt, regions of iodine excess, and the potential effects of initiatives to lower population sodium consumption on iodine intake. Although substantial progress has been made over the last several decades, iodine deficiency remains a significant health problem worldwide and affects both industrialized and developing nations. The ongoing monitoring of population iodine status remains crucially important, and particular attention may need to be paid to monitoring the status of vulnerable populations, such as pregnant women and infants. There is also need for ongoing monitoring of iodized salt and other dietary iodine sources in

Energy Partitioning in the Dissociation of Cyanogen at 193nm,

DTIC Science & Technology

1981-11-19

r AD-AlA? 773 HOWARD UNIV WASHINGTON DC LASER CHEMISTRY DIV FIG 7/5 ENERGY PARTITIONING IN THE DISSOCIATION OF CYANOGEN AT 193NM. CU) NOV 81 W M...DRFSS 10. PROGRAM ELEMENT. PROJECT, TASK Laser Chemistry Division . AREA & WORK UNIT tUMaeRS Department of Chemistry Howard University Washington, D. C... Chemistry . 19. KEY OOROS (Continue on reverse aide If necessary and Identify by block number) Photodissociation, laser photodissociation, cyanogen C’ m 20

Impact of removing iodized salt on the iodine nutrition of children living in areas with variable iodine content in drinking water.

PubMed

Lv, Shengmin; Zhao, Yinglu; Li, Yanxia; Wang, Yuchun; Liu, Hua; Li, Yang; Zhao, Jun; Rutherford, Shannon

2015-09-01

Excess iodine in drinking water has emerged as a public health issue in China. This study assesses the effectiveness of removing iodized salt on reducing the iodine excess in populations living in high-iodine areas and also to identify the threshold value for safe levels of iodine in water. Twelve villages from 5 cities of Hebei Province with iodine content in drinking water ranging from 39 to 313 µg/l were selected to compare the urinary iodine content of children aged 8-10 years before and after removing iodized salt from their diet. For 3 villages where median water iodine content (MWIC) was below 110 µg/l, following the removal of iodized salt (the intervention), the median urinary iodine content (MUIC) reduced to under 300 µg/l decreasing from 365, 380, 351 to 247, 240, 281 µg/l, respectively. However, the MUIC in the 9 villages with MWIC above 110 µg/l remained higher than 300 µg/l. The children's MUIC correlated positively with the MWIC in the 12 villages (p ≤ 0.001). The linear regression equation after removing iodized salt was MUIC = 0.6761MWIC + 225.67, indicating that to keep the MUIC below 300 µg/l (the iodine excess threshold recommended by the WHO) requires the MWIC to be under 110 µg/l. Removing iodized salt could only correct the iodine excess in the population living in the areas with MWIC below 110 µg/l. In the areas with water iodine above 110 µg/l, interventions should be focused on seeking water with lower iodine content. This study suggests a threshold value of 110 µg/l of iodine in drinking water to maintain a safe level of dietary iodine.

Mission and System Advantages of Iodine Hall Thrusters

NASA Technical Reports Server (NTRS)

Dankanich, John W.; Szabo, James; Pote, Bruce; Oleson, Steve; Kamhawi, Hani

2014-01-01

The exploration of alternative propellants for Hall thrusters continues to be of interest to the community. Investments have been made and continue for the maturation of iodine based Hall thrusters. Iodine testing has shown comparable performance to xenon. However, iodine has a higher storage density and resulting higher ?V capability for volume constrained systems. Iodine's vapor pressure is low enough to permit low-pressure storage, but high enough to minimize potential adverse spacecraft-thruster interactions. The low vapor pressure also means that iodine does not condense inside the thruster at ordinary operating temperatures. Iodine is safe, it stores at sub-atmospheric pressure, and can be stored unregulated for years on end; whether on the ground or on orbit. Iodine fills a niche for both low power (<1kW) and high power (>10kW) electric propulsion regimes. A range of missions have been evaluated for direct comparison of Iodine and Xenon options. The results show advantages of iodine Hall systems for both small and microsatellite application and for very large exploration class missions.

Sublimation of Iodine at Various Pressures

ERIC Educational Resources Information Center

Leenson, Ilya A.

2005-01-01

Various phenomena that are observed in the process of heating solid iodine in closed vessels at different pressures and temperatures are described. When solid iodine is heated in an evacuated ampoule where the pressure is less than 10(super -3), no noticeable color appears and immediate condensation of tiny iodine crystals is visible higher up on…

The role of iodine in human growth and development.

PubMed

Zimmermann, Michael B

2011-08-01

Iodine is an essential component of the hormones produced by the thyroid gland. Thyroid hormones, and therefore iodine, are essential for mammalian life. Iodine deficiency is a major public health problem; globally, it is estimated that two billion individuals have an insufficient iodine intake. Although goiter is the most visible sequelae of iodine deficiency, the major impact of hypothyroidism due to iodine deficiency is impaired neurodevelopment, particularly early in life. In the fetal brain, inadequate thyroid hormone impairs myelination, cell migration, differentiation and maturation. Moderate-to-severe iodine deficiency during pregnancy increases rates of spontaneous abortion, reduces birth weight, and increases infant mortality. Offspring of deficient mothers are at high risk for cognitive disability, with cretinism being the most severe manifestation. It remains unclear if development of the offspring is affected by mild maternal iodine deficiency. Moderate-to-severe iodine deficiency during childhood reduces somatic growth. Correction of mild-to-moderate iodine deficiency in primary school aged children improves cognitive and motor function. Iodine prophylaxis of deficient populations with periodic monitoring is an extremely cost effective approach to reduce the substantial adverse effects of iodine deficiency throughout the life cycle. Copyright © 2011 Elsevier Ltd. All rights reserved.

[Iodine concentration in cooking salt consumed in Lubumbashi and the iodine status of vulnerable people: case study of pregnant women living in underprivileged areas].

PubMed

Banza, Bienvenue Ilunga; Lumbu, Jean Baptiste Simbi; Donnen, Philippe; Twite, Eugène Kabange; Kwete, Daniel Mikobi; Kazadi, Costa Mwadianvita; Ozoza, Jean Okolonken; Habimana, Laurence; Kalenga, Prosper Muenze Kayamba; Robert, Annie

2016-01-01

Consumption of low iodine salt can cause different types of disorders associated with iodine deficiency. This study aims to determine iodine content in table salt consumed in Lubumbashi and iodine status of pregnant women who are the main target of iodine deficiency. aAdescriptive cross-sectional study was devoted to an iodometric iodine analysis of 739 salt samples collected from the households and the markets of Lubumbashi in 2014. Previously, urinary iodine concentrations were determined in 225 pregnant women received for consultation from 15 March 2009 to 25 April 2011 by mineralization technique using ammonium persulphate. Our survey found that 47.5% of the cooking salt samples were adequately iodized (from 15 to 40 ppm), 36,9% of the samples had low iodine levels, 7,4% of the samples had too much iodine and 8,1% of the samples were not iodized. Iodine concentration in the analyzed cooking salt reached an overall average of 54,9%, being clearly below the WHO Standards (90%). By measuring urinary iodine concentration of pregnant women, iodine deficiency (urinary iodine <150 µg/l) was observed in 52%. The low availability of iodine from consumed salt in Lubumbashi could be responsible for a large proportion of the observed iodine deficiency in pregnant women, exposing them to the major risks for disorders associated with iodine deficiency.

Formation of iodinated trihalomethanes during UV/chloramination with iodate as the iodine source.

PubMed

Zhang, Tian-Yang; Lin, Yi-Li; Wang, An-Qi; Tian, Fu-Xiang; Xu, Bin; Xia, Sheng-Ji; Gao, Nai-Yun

2016-07-01

Iodinated trihalomethanes (I-THMs) are a group of emerging disinfection by-products with high toxicity, and iodide (I(-)) as well as iodinated organic compounds are expected to be their iodine sources. Nevertheless, in this study, iodate (IO3(-)) was proven to be a new iodine source of I-THM formation during UV/chloramination. In the iodate-containing waters (without any other iodine sources), I-THM formation increased with the increase of UV dose, IO3(-) and NH2Cl concentrations. With the increase of Br(-)/IO3(-) molar ratio, I-THM formation (especially for the brominated species) increased. Besides, NOM species could affect I-THM formation from IO3(-) during UV/chloramination. Fulvic acid could promote IO3(-) phototransformation to I(-) but humic acid impeded the production of I(-) during UV irradiation. Under realistic drinking water treatment conditions (DOC = 5.0 mg-C/L, IO3(-) = 12.7 μg-I/L, UV dose = 50 mJ/cm(2), NH2Cl = 5 mg-Cl2/L), CHCl2I was detected as 0.17 μg/L using solid-phase microextraction method, and the production rate of I-THMs from IO3(-) was about 7% of that from I(-). Copyright © 2016 Elsevier Ltd. All rights reserved.

Theoretical studies of solar lasers and converters

NASA Technical Reports Server (NTRS)

Heinbockel, John

1988-01-01

The geometry and setup for the n-C3F7I iodine laser are illustrated. The mathematical modeling of this system is described. The chemical kinetics are summarized. A sensitivity analysis was performed on the parameters occurring in the differential equations describing the chemical kinetics.

Theoretical studies of solar lasers and converters

NASA Technical Reports Server (NTRS)

Heinbockel, John H.

1988-01-01

The previously constructed one dimensional model for the simulated operation of an iodine laser assumed that the perfluoroalkyl iodide gas n-C3F7I was incompressible. The present study removes this simplifying assumption and considers n-C3F7I as a compressible fluid.

Thermal Smoothing by Laser-Produced Plasma of Porous Matter

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kalal, M.; Limpouch, J.; Krousky, E.

2003-05-15

Efficient energy transfer and smoothing effect in laser-irradiated polystyrene foam targets have been observed in preliminary experiments on the PALS iodine laser facility. A theory of laser light absorption region formation and ablation pressure generation in laser-produced plasma of porous matter has been developed and applied for discussion of the results obtained. In particular, two stages of homogenization of the porous matter, important for comprehension of the anomalously high absorption of laser radiation in supercritical foam matter, have been identified: the first, a considerably fast stage of partial homogenization, followed by a much slower second stage, leading to a uniformmore » medium.« less

Iodine Tagging Velocimetry and Mechanism in the Hypersonic Near Wake of a MultiPurpose Crew Vehicle

NASA Technical Reports Server (NTRS)

Balla, R. Jeffrey

2013-01-01

This study demonstrates a new molecular tagging velocimetry (MTV) method for velocity measurements of high speed flow. It demonstrates offbody Iodine Tagging Velocimetry (ITV) in the hypersonic near wake of a MultiPurpose Crew Vehicle (MPCV) model. Experiments are performed in the NASA-Langley 31-inch Mach 10 air wind tunnel. A 0.5% I2 / N2 mixture is seeded on the leeward backshell of the model using a pressure tap. I2 laser-induced fluorescence is excited along a 5.5 mm line using an ArF excimer laser near 193 nm. Results indicate I2 absorbs at least 2 photons to produce iodine ions and electrons. These recombine as the tagged region is displaced downstream to produce I (2P3/2) whose emission is monitored at 206 nm. Results at P0 = 2.41 MPa (350 psi), T0 = 990K, and 10 micro-sec transit times produce velocities from 630-820 m/sec across the I2 seeded jet at a distance of 38.2 mm (25.5 jet diameters) downstream from the jet orifice. Maximum wake jet velocities near the shear layer are 59% of freestream velocity.

IODINE CONTENT OF ENTERAL AND PARENTERAL NUTRITION SOLUTIONS.

PubMed

Willard, Devina L; Young, Lorraine S; He, Xuemei; Braverman, Lewis E; Pearce, Elizabeth N

2017-07-01

Iodine is essential for thyroid hormone synthesis, and iodine deficiency may result in thyroid disorders including goiter and hypothyroidism. Patients on long-term enteral nutrition (EN) or parenteral nutrition (PN) may be at risk for micronutrient deficiencies. The recommended daily allowance for iodine intake is 150 μg for nonpregnant adults. However, there is no current consensus among scientific societies regarding the quantity of iodine to be added in adult EN and PN formulations. The objective of this study was to determine the iodine content of U.S. adult enteral and parenteral nutrition solutions. This study also aimed to determine whether adult patients in the United States who are receiving long-term artificial nutrition may be at risk for iodine deficiency. Ten enteral nutrition solutions and 4 parenteral nutrition solutions were evaluated. The iodine contents of these solutions were measured spectrophotometrically and compared to the labeled contents. Measured and labeled EN iodine contents were similar (range 131-176 μg/L and 106-160 μg/L, respectively). In contrast, PN formulas were found to contain small, unlabeled amounts of iodine, averaging 27 μg/L. Typical fluid requirements are 30 to 40 mL/kg/day for adults receiving either total EN (TEN) or total PN (TPN). Adults on long-term TEN likely consume enough servings to meet their daily iodine requirements. However, patients on long-term TPN would require on average 5.6 L PN/day to meet the recommended daily allowance of iodine. This volume of PN is far in excess of typical consumption. Thus, U.S. patients requiring long-term TPN may be at risk for iodine deficiency. EN = enteral nutrition; PN = parenteral nutrition; TEN = total enteral nutrition; TPN = total parenteral nutrition; UIC = urinary iodine concentration.

[Iodine deficiency and pregnancy].

PubMed

Trimarchi, F; Lo Presti, V P; Vermiglio, F

1998-01-01

Iodine availability for maternal thyroid during pregnancy results from a combination of specific factors (increased urinary iodine loss, fetal-placental unit competition) and is critically reduced by the nutritional deficiency. Hyperestrogenism is associated with increased circulating thyroxine-binding globulin (TBG) levels and a higher binding capacity for T4 and T3, because of a reduced clearance rate of the protein. Our study carried out in a moderately iodine deficiency area from North-Eastern Sicily in pregnant women showed a inadequate synthesis of T4 not proportional to the increased TBG levels. The progressive decrease T4/TBG molar ratio implies the reduction of serum FT4 and the consequently increase of serum TSH. At delivery, about 70% of women showed a critical and transient biochemical hypothyroidism. Mental impairment and neurosensorial and neuromuscular disorders were observed in children born from those women. Therefore, short-term iodine prophylaxis with iodized salt in pregnant women does not correct nor prevent maternal hypothyroxinemia. L-T4 treatment is thus often required.

157 nm Photodissociation of Dipeptide Ions Containing N-Terminal Arginine

NASA Astrophysics Data System (ADS)

Webber, Nathaniel; He, Yi; Reilly, James P.

2014-02-01

Twenty singly-charged dipeptide ions with N-terminal arginine were photodissociated using 157 nm light in both a linear ion-trap mass spectrometer and a MALDI-TOF-TOF mass spectrometer. Analogous to previous work on dipeptides containing C-terminal arginine, this set of samples enabled insights into the photofragmentation propensities associated with individual residues. In addition to familiar products such as a-, d-, and immonium ions, m2 and m2+13 ions were also observed. Certain side chains tended to cleave between their β and γ carbons without necessarily forming d- or w-type ions, and a few other ions were produced by the high-energy fragmentation of multiple bonds.

Photoabsorption and photodissociation of molecules important in the interstellar medium

NASA Technical Reports Server (NTRS)

Lee, Long C.; Suto, Masako

1991-01-01

The photoabsorption, photodissociation, and fluorescence cross sections of interstellar molecules are measured at 90 to 250 nm. These quantitative optical data are needed for the understanding of the formation and destruction processes of molecules under the intense interstellar UV radiation field. Research covering the following topics is presented: (1) fluorescences from photoexcitation of CH4, CH3OH, and CH3SH; (2) NO gamma emission from photoexcitation of NO; (3) photoexcitation cross sections of aromatic molecules; (4) IR emission from UV excitation of HONO2; (5) IR emission from UV excitation of benzene and methyl-derivitives; and (6) IR emission from UV excitation of polycyclic aromatic hydrocarbon molecules.

Laser induced photoluminiscence studies of primary photochemical production processes of cometary radicals

NASA Technical Reports Server (NTRS)

Jackson, W. M.

1977-01-01

A tunable vacuum ultraviolet flash lamp was constructed. This unique flash lamp was coupled with a tunable dye laser detector and permits the experimenter to measure the production rates of ground state radicals as a function of wavelength. A new technique for producing fluorescent radicals was discovered. This technique called multiphoton ultraviolet photodissociation is currently being applied to several problems of both cometary and stratospheric interest. It was demonstrated that NO2 will dissociate to produce an excited fragment and the radiation can possibly be used for remote detection of this species.

Consensus statement on iodine deficiency disorders in Hong Kong.

PubMed

But, Betty; Chan, C W; Chan, Fredriech; Chan, K W; Cheng, Anna W F; Cheung, Patrick; Choi, K L; Chow, C B; Chow, Francis C C; Eastman, Creswell; Fok, T F; Fung, L M; Gomes, Cynthia; Huen, K F; Ip, T P; Kung, Annie W C; Lam, Karen S L; Lam, Y Y; Lao, Terence; Lee, C Y; Lee, K F; Leung, Jenny; Leung, N K; Li, Dominic; Li, June; Lo, K W; Lo, Louis; Ng, K L; Siu, S C; Tam, Sidney; Tan, Kathryn C B; Tiu, S C; Tse, H Y; Tse, Winnie; Wong, Gary; Wong, Shell; Wong, William; Yeung, Vincent T F; Young, Rosie; Yu, C M; Yu, Richard

2003-12-01

This article reviews the available data on the study of iodine deficiency disorders in Hong Kong and to discuss the approach towards preventing such disorders in Hong Kong. The importance of iodine and iodine deficiency disorders is described, and the available data on the dietary iodine intake and urinary iodine concentration in different populations of Hong Kong are summarised and discussed. Dietary iodine insufficiency among pregnant women in Hong Kong is associated with maternal goitrogenesis and hypothyroxinaemia as well as neonatal hypothyroidism. Borderline iodine deficiency exists in the expectant mothers in Hong Kong. Women of reproductive age, and pregnant and lactating women should be made aware and educated to have an adequate iodine intake, such as iodised salt, as an interim measure. A steering group involving all stakeholders should be formed to advise on the strategy of ensuring adequate iodine intake, including universal iodisation of salt in Hong Kong. Continuous surveillance of iodine status in the Hong Kong population is necessary.

Iodinated Contrast Media and the Alleged "Iodine Allergy": An Inexact Diagnosis Leading to Inferior Radiologic Management and Adverse Drug Reactions.

PubMed

Böhm, Ingrid; Nairz, Knud; Morelli, John N; Keller, Patricia Silva Hasembank; Heverhagen, Johannes T

2017-04-01

Purpose  To test the hypothesis that the incomplete diagnosis "iodine allergy" is a possibly dangerous concept for patients under routine radiologic conditions. Materials and Methods  300 patients with a history of an "iodine allergy" were retrospectively screened and compared with two age-, sex-, and procedure-matched groups of patients either diagnosed with a nonspecific "iodine contrast medium (ICM) allergy" or an allergy to a specific ICM agent. For all groups, the clinical symptoms of the most recent past adverse drug reaction (ADR), prophylactic actions taken for subsequent imaging, and ultimate outcome were recorded and analyzed. Results  The diagnosis "iodine allergy" was not otherwise specified in 84.3 % patients. For this group, in most cases, the symptoms of the previous ADRs were not documented. In contrast, the type of ADR was undocumented in only a minority of patients in the comparison groups. In the group of patients with an "iodine allergy" the percentage of unenhanced CT scans was greater than within the other two groups (36.7 % vs. 28.7 %/18.6 %). ADRs following prophylactic measures were only observed in the "iodine allergy" group (OR of 9.24 95 % CI 1.16 - 73.45; p < 0.04). Conclusion  This data confirms the hypothesis that the diagnosis "iodine allergy" is potentially dangerous and results in uncertainty in clinical management and sometimes even ineffective prophylactic measures. Key points   · The term "iodine allergy" is imprecise, because it designates allergies against different substance classes, such as disinfectants with complexed iodine and contrast media containing covalently bound iodine.. · There is a clear correlation between the exactness of the diagnosis - from the alleged "iodine allergy" to "contrast media allergy" to naming the exact culprit CM - and the quality of documentation of the symptoms.. · Management of patients diagnosed with "iodine allergy" was associated with uncertainty leading to

Iodine Status in Pregnant Women, Lactating Mothers, and Newborns in an Area with More Than Two Decades of Successful Iodine Nutrition.

PubMed

Nazeri, Pantea; Zarghani, Najmeh Hamzavi; Mirmiran, Parvin; Hedayati, Mehdi; Mehrabi, Yadollah; Azizi, Fereidoun

2016-07-01

Pregnant women, lactating mothers, and their newborns constitute the target population for prevention and control of iodine deficiency. Hence, the aim of this study was to evaluate the iodine nutrition status among these vulnerable groups in an area with more than two decades of successful elimination of iodine deficiency. In this cross-sectional study conducted in health care centers of Tehran, 100 pregnant women and 84 lactating mothers and their newborn were randomly selected. Urinary iodine concentration and iodine content of salts were measured using the Sandell-Kolthoff and titration methods, respectively. Urinary iodine concentration <150 μg/L for pregnant women and <100 μg/L for lactating mothers and newborns was considered as iodine nutrition inadequacy, respectively. Median (interquartile range [IQR]) urinary iodine concentration (UIC) was 103 (59-155) μg/L in pregnant women, 77 (42-194) μg/L in lactating mothers, and 198 (84-260) μg/L in newborns. Median (IQR) iodine content of salt was 26 (21-30) ppm and 25 (18-28) ppm in pregnant women and lactating mothers, respectively (P = 0.462). Iodine content of salt was significantly correlated with UIC of pregnant women (r = 0.24, P = 0.019), but no correlation was found among lactating mothers (r = 0.12, P = 0.316). Neonatal UIC was significantly correlated with iodine content of salt consumed by their mothers (r = 0.49, P = 0.001). Despite suboptimal iodine status among subgroups of Tehranian pregnant and lactating women, iodine nutrition status of newborns was within optimal levels, which may be explained by a compensatory mechanism in the mammary glands.

Recent experiences with iodine water disinfection in Shuttle

NASA Technical Reports Server (NTRS)

Gibbons, Randall E.; Flanagan, David T.; Schultz, John R.; Sauer, Richard L.; Slezak, Terry N.

1990-01-01

Microbial proliferation in the STS potable water system is prevented by maintaining a 2-5 ppm iodine residual. The iodine is added to fuel cell water by an iodinated ion exchange resin in the Microbial Check Valve (MCV). Crew comments indicated excessive iodine in the potable water. To better define the problem, a method of in-flight iodine analysis was developed. Inflight analysis during STS-30 and STS-28 indicated iodine residuals were generally in the 9-13 ppm range. It was determined that the high iodine residual was caused by MCV influent temperatures in excess of 120 F. This is well above the MCV operating range of 65-90 F. The solution to this problem was to develop a resin suitable for the higher temperatures. Since 8 months were required to formulate a MCV resin suitable for the higher temperatures, a temporary solution was necessary. Two additional MCV's were installed on the chilled and ambient water lines leading into the galley to remove the excess iodine. These reduced the iodine residual to 3-4 ppm during STS-33, STS-34, STS-36 and STS-32. A high-temperature resin was formulated and initially flown on STS-31.

Systematic review using meta-analyses to estimate dose-response relationships between iodine intake and biomarkers of iodine status in different population groups.

PubMed

Ristić-Medić, Danijela; Dullemeijer, Carla; Tepsić, Jasna; Petrović-Oggiano, Gordana; Popović, Tamara; Arsić, Aleksandra; Glibetić, Marija; Souverein, Olga W; Collings, Rachel; Cavelaars, Adriënne; de Groot, Lisette; van't Veer, Pieter; Gurinović, Mirjana

2014-03-01

The objective of this systematic review was to identify studies investigating iodine intake and biomarkers of iodine status, to assess the data of the selected studies, and to estimate dose-response relationships using meta-analysis. All randomized controlled trials, prospective cohort studies, nested case-control studies, and cross-sectional studies that supplied or measured dietary iodine and measured iodine biomarkers were included. The overall pooled regression coefficient (β) and the standard error of β were calculated by random-effects meta-analysis on a double-log scale, using the calculated intake-status regression coefficient (β) for each individual study. The results of pooled randomized controlled trials indicated that the doubling of dietary iodine intake increased urinary iodine concentrations by 14% in children and adolescents, by 57% in adults and the elderly, and by 81% in pregnant women. The dose-response relationship between iodine intake and biomarkers of iodine status indicated a 12% decrease in thyroid-stimulating hormone and a 31% decrease in thyroglobulin in pregnant women. The model of dose-response quantification used to describe the relationship between iodine intake and biomarkers of iodine status may be useful for providing complementary evidence to support recommendations for iodine intake in different population groups.

[Study on the amount of daily iodine intake of inhabitants living in drinking water with excessive iodine content areas after termination of iodized salt supply].

PubMed

Zhang, Gen-hong; Li, Su-mei; Zheng, He-ming; Wang, Chuan-gang; Liu, Lie-jun; Li, Xiu-wei; Zhang, Hao-feng; Ke, Geng-yin; Ma, Jian-guo; Yang, Jin; Ma, Ying; Liu, Jin-wen

2007-03-01

To investigate the amount of daily iodine intake in the diet of the target population in drinking water with areas of excessive iodine after stopping supply of iodized salt, to provide evidence for developing strategies on control and prevention of excessive iodine. 335 objectives were selected by a two-stage sampling method in 4 administrative villages with different iodine contents in drinking water. The amount of drinking water intake and dietary survey for 335 people were done by a door-to-door survey,while the iodine contents in the drinking water of each selected family, local staple food and vegetable were measured. The median level of iodine in drinking water was 431.5 microg/L while the daily amount of iodine intake among the three groups of waters with different iodine contents were all greater than RNI. The daily iodine intake of local people was all greater than UL in the areas where the water iodine contents were more than 300 microg/L. It was of statistical sense that the iodine mean intake per capita per day of the three groups differed at different water iodine levels (P < 0.01). The iodine mean intake per capita per day of the three groups of different water iodine levels increased along with water iodine and showed a uptrend (P < 0.01). 83.2%-98.7% of the daily iodine intake of the three groups was from drinking water and 1.3%-16.8% came from food. The iodine intake had high-positive correlation relation with the content of water iodine (P < 0.01). It was concluded that drinking water was the main source of iodine intake in areas with iodine excessive water by the percentage of over 80%. It was necessary to adopt measures to improve the quality of water to decrease the iodine content other than just stopping supplies of iodized salt in the areas where the water iodine contents were greater than 300 microg/L, in order to prevent and control excessive intake of iodine.

Total iodine quantification in fluids and tissues from iodine- or iodide-supplemented rats by ion chromatography following microwave-assisted digestion.

PubMed

Delgado, Guadalupe; Muñoz-Torres, Carolina; Orozco-Esquivel, Teresa; Anguiano, Brenda; Aceves, Carmen

2015-03-01

Iodine is a crucial component of thyroid hormones, and several reports have shown that iodine per se is implicated in the physiopathology of other organs. Innovative ion chromatography detection following a four-step temperature ramp microwave digestion in 25-50 mM nitric acid was developed to measure total iodine in biological fluids and tissue samples from female Sprague-Dawley rats supplemented with 0.05% molecular iodine (I2) or 0.05% potassium iodide (I(-)) in drinking water. The reported method allows the measurement of total iodine with a limit of quantification of 13.7 μg L(-1), recoveries of 96.3-100.3%, and intra- and inter-assay variations, of 3.5% and 7.4% respectively. Analysis of biological fluids showed that after 48 hours, iodine-supplemented animals exhibited significantly higher levels of total iodine in both serum and urine compared with those supplemented with iodide. The half-life of iodine in serum and urine measured over the first 48 h showed similar patterns for both the I2 (7.89 and 7.76 hours) and I(-) (8.27 and 8.90 hours) supplements. Differential uptake patterns were observed in tissues after 6 days of supplements, with I(-) preferentially retained by thyroid, lactating mammary gland, and milk, and a slightly but significantly higher capture of I2 in pituitary, ovary, and virgin mammary gland. We developed a rapid, selective, and accurate digestion method to process fluid and tissue samples that permits reproducible measurements of total iodine by ion chromatography; iodine or iodide supplement show a similar serum and urine half-life, but organ-specific uptake depends on the chemical form of the iodine supplement.

Post-production losses in iodine concentration of salt hamper the control of iodine deficiency disorders: a case study in northern Ethiopia.

PubMed

Shawel, Dawit; Hagos, Seifu; Lachat, Carl K; Kimanya, Martin E; Kolsteren, Patrick

2010-06-01

Iodine is essential for good function of the thyroid, and its deficiency is of public-health importance in Ethiopia. Iodization of salt is an effective and sustainable strategy to prevent and control iodine deficiency in large populations. The effectiveness of salt-iodization programmes depends on the conservation of iodine concentration in salt at various stages of the supply-chain. The overall objective of the study was to assess the loss of iodine in salt from production to consumption and to estimate the proportion of adults, especially pregnant women, at risk of dietary iodine insufficiency. A cross-sectional study was conducted during February-April 2007 in northern Ethiopia. Iodine concentrations of salt samples from producers (n=41), retailers (n=7), and consumers (n=32) were determined using iodiometric titration. A risk assessment was conducted for dietary iodine insufficiency among adults, including pregnant women, using a semi-probabilistic approach. The concentration of iodine in the sampled salts decreased by 57% from the production site to the consumers. The assessment of exposure showed that adults in 63% (n=20) of the households, including 90% (n=29) with pregnant women, were at risk of insufficient iodine intake. A monitoring and evaluation system needs to be established to ensure adequate supply of iodine along the distribution chain. Special attention is needed for the retailers and consumers. At these levels, dissemination of information regarding proper storage and handling of iodized salt is necessary to address the reported loss of iodine from salt.

Iodine deficiency in pregnant women living in the South East of the UK: the influence of diet and nutritional supplements on iodine status.

PubMed

Bath, Sarah C; Walter, Alan; Taylor, Andrew; Wright, John; Rayman, Margaret P

2014-05-01

Iodine is a key component of the thyroid hormones which are crucial for brain development. Adequate intake of iodine in pregnancy is important as in utero deficiency may have lifelong consequences for the offspring. Data on the iodine status of UK pregnant women are sparse, and there are no such data for pregnant women in the South East of the UK. A total of 100 pregnant women were recruited to a cross-sectional study carried out at the Royal Surrey County Hospital, Guildford, at their first-trimester visit for an ultrasound scan. The participants provided a spot-urine sample (for the measurement of urinary iodine concentration (UIC) and creatinine concentration) and 24 h iodine excretion was estimated from the urinary iodine:creatinine ratio. Women completed a general questionnaire and a FFQ. The median UIC (85·3 μg/l) indicated that the group was iodine deficient by World Health Organisation criteria. The median values of the iodine:creatinine ratio (122·9 μg/g) and of the estimated 24 h iodine excretion (151·2 μg/d) were also suggestive of iodine deficiency. UIC was significantly higher in women taking an iodine-containing prenatal supplement (n 42) than in those not taking such a supplement (P< 0·001). In the adjusted analyses, milk intake, maternal age and iodine-containing prenatal supplement use were positively associated with the estimated 24 h urinary iodine excretion. Our finding of iodine deficiency in these women gives cause for concern. We suggest that women of childbearing age and pregnant women should be given advice on how to improve their iodine status through dietary means. A national survey of iodine status in UK pregnant women is required.

MARGINAL IODINE DEFICIENCY EXACERBATES PERCHLORATE THYROID TOXICITY.

EPA Science Inventory

The environmental contaminant perchlorate disrupts thyroid homeostasis via inhibition of iodine uptake into the thyroid. This work tested whether iodine deficiency exacerbates the effects of perchlorate. Female 27 day-old LE rats were fed a custom iodine deficient diet with 0, 50...

Hydrogen isotope separation from water

DOEpatents

Jensen, R.J.

1975-09-01

A process for separating tritium from tritium-containing water or deuterium enrichment from water is described. The process involves selective, laser-induced two-photon excitation and photodissociation of those water molecules containing deuterium or tritium followed by immediate reaction of the photodissociation products with a scavenger gas which does not substantially absorb the laser light. The reaction products are then separated from the undissociated water. (auth)

Development of Databases on Iodine in Foods and Dietary Supplements

PubMed Central

Ershow, Abby G.; Skeaff, Sheila A.; Merkel, Joyce M.; Pehrsson, Pamela R.

2018-01-01

Iodine is an essential micronutrient required for normal growth and neurodevelopment; thus, an adequate intake of iodine is particularly important for pregnant and lactating women, and throughout childhood. Low levels of iodine in the soil and groundwater are common in many parts of the world, often leading to diets that are low in iodine. Widespread salt iodization has eradicated severe iodine deficiency, but mild-to-moderate deficiency is still prevalent even in many developed countries. To understand patterns of iodine intake and to develop strategies for improving intake, it is important to characterize all sources of dietary iodine, and national databases on the iodine content of major dietary contributors (including foods, beverages, water, salts, and supplements) provide a key information resource. This paper discusses the importance of well-constructed databases on the iodine content of foods, beverages, and dietary supplements; the availability of iodine databases worldwide; and factors related to variability in iodine content that should be considered when developing such databases. We also describe current efforts in iodine database development in the United States, the use of iodine composition data to develop food fortification policies in New Zealand, and how iodine content databases might be used when considering the iodine intake and status of individuals and populations. PMID:29342090

Evidence of iodine storage within thyroid stroma after iodine treatment: imaging by secondary ion mass spectometry (SIMS) microscopy in goitrous tissue.

PubMed

el May, M; Jeusset, J; el May, A; Mtimet, S; Fragu, P

1996-06-01

We measured the 127I distribution within tyroid tissue to find out where intrathyroid iodine was deposited during iodine treatment in eight Tunisian female patients (aged 33-58 yr) with endemic euthyroid goiter. Before surgery, five patients were treated during 6 months either by Lugol's solution (group 1: three patients) or by Lugol's and L-thyroxine (group 2: two patients). All patients remained euthyroid during the course of the treatment, which supplied 3.8 mg/day iodine. Three other patients did not receive Lugol's solution (control group). Secondary ion mass spectrometry microscopy was used to map 127-I quantitatively on thyroid sections. Specimens obtained at thyroid surgery were divided macroscopically into nodular and extranodular tissue and chemically fixed to preserve organified iodine. The iodine profile of patients in group 1 did not differ from that in group 2: large amounts of iodine were localized in thyroid follicles and stroma of both nodular and extranodular tissues. In the control group, iodine within stroma was found only in the extranodular tissue. Despite the limited number of patients studied, these data suggest that stromal iodine might represent a storage compartment in times of large iodine supply.

Dry method for recycling iodine-loaded silver zeolite

DOEpatents

Thomas, Thomas R.; Staples, Bruce A.; Murphy, Llewellyn P.

1978-05-09

Fission product iodine is removed from a waste gas stream and stored by passing the gas stream through a bed of silver-exchanged zeolite until the zeolite is loaded with iodine, passing dry hydrogen gas through the bed to remove the iodine and regenerate the bed, and passing the hydrogen stream containing the hydrogen iodide thus formed through a lead-exchanged zeolite which adsorbs the radioactive iodine from the gas stream and permanently storing the lead-exchanged zeolite loaded with radioactive iodine.

Current challenges in meeting global iodine requirements.

PubMed

Eastman, Creswell J; Jooste, Pieter

2012-01-01

Iodine deficiency is a global problem of immense magnitude afflicting 2 billion of the world's population. The adverse effects of iodine deficiency in humans, collectively termed iodine deficiency disorders, result from decreased thyroid hormone production and action, and vary in severity from thyroid enlargement (goiter) to severe, irreversible brain damage, termed endemic cretinism. Thyroid hormone is essential throughout life, but it is critical for normal brain development in the fetus and throughout childhood. During pregnancy, maternal thyroid hormone production must increase by 25-50% to meet maternal-fetal requirements. The principal sources of iodine in the diet include milk and dairy products, seafoods and foods with added iodized salt. Vegetables, fruits and cereals are generally poor sources of iodine because most of our soils and water supplies are deficient in iodine. The accepted solution to the problem is Universal Salt Iodization where all salt for human and animal consumption is iodized at a level of 20-40 µg/g. In principle, mandatory fortification represents the most effective public health strategy where safety and efficacy can be assured and there is a demonstrated need for the nutrient in the population. Voluntary fortification of salt and other foods has many limitations and few benefits. Iodine supplementation is a useful, but expensive, inefficient and unsustainable strategy for preventing iodine deficiency. The current worldwide push to decrease salt intake to prevent cardiovascular disease presents an entirely new challenge in addressing iodine deficiency in both developing and developed countries. Copyright © 2012 S. Karger AG, Basel.

[Iodine and thyroid gland with or without nuclear catastrophe].

PubMed

Dilas, Ljiljana Todorović; Bajkin, Ivana; Icin, Tijana; Paro, Jovanka Novaković; Zavisić, Branka Kovacev

2012-01-01

Iodine, as a trace element, is a necessary and limiting substrate for thyroid gland hormone synthesis. It is an essential element that enables the thyroid gland to produce thyroid hormones thyroxine (T4) and triiodothyronine (T3). Synthesis of Thyroid Hormones and Iodine Metabolism. Three iodine molecules are added to make triiodothyronine, and four for thyroxine - the two key hormones produced by the thyroid gland. Iodine deficiency The proper daily amount of iodine is required for optimal thyroid function. Iodine deficiency can cause hypothyroidism, developmental brain disorders and goiter. Iodine deficiency is the single most common cause of preventable mental retardation and brain damage in the world. It also decreases child survival, causes goiters, and impairs growth and development. Iodine deficiency disorders in pregnant women cause miscarriages, stillbirths, and other complications. Children with iodine deficiency disorders can grow up stunted, apathetic, mentally retarded, and incapable of normal movements, speech or hearing. Excessive Iodine Intake. Excessive iodine intake, which can trigger a utoimmune thyroid disease and dysfunction. is on the other side. Iodine use in Case of Nuclear Catastrophe. In addition to other severe consuquences of radioactivity, high amount of radioactive iodine causes significant increase in incidence of thyroid gland carcinoma after some of the nuclear catastrophes (Hiroshima, Nagasaki, Chernobyl, Fukushima). The incidence of thyroid carcinoma was increased mostly in children. This paper was aimed at clarifying some of the possibilities of prevention according to the recommendations given by the World Health Organization.

Active vs. spectator modes in nonadiabatic photodissociation dynamics of the hydroxymethyl radical via the 22A(3s) Rydberg state

NASA Astrophysics Data System (ADS)

Xie, Changjian; Guo, Hua

2018-01-01

The choice of the active degrees of freedom (DOFs) is a pivotal issue in a reduced-dimensional model of quantum dynamics when a full-dimensional one is not feasible. Here, several five-dimensional (5D) models are used to investigate the nonadiabatic photodissociation dynamics of the hydroxymethyl (CH2OH) radical, which possesses nine internal DOFs, in its lowest absorption band. A normal-mode based scheme is used to identify the active and spectator modes, and its predictions are confirmed by 5D quantum dynamical calculations. Our results underscore the important role of the CO stretching mode in the photodissociation dynamics of CH2OH, originating from the photo-induced promotion of an electron from the half-occupied π*CO antibonding orbital to a carbon Rydberg orbital.

Comparison of femtosecond- and nanosecond-two-photon-absorption laser-induced fluorescence (TALIF) of atomic oxygen in atmospheric-pressure plasmas

NASA Astrophysics Data System (ADS)

Schmidt, Jacob B.; Sands, Brian; Scofield, James; Gord, James R.; Roy, Sukesh

2017-05-01

Absolute number densities of atomic species produced by nanosecond (ns)-duration, repetitively pulsed electric discharges are measured by two-photon-absorption laser-induced fluorescence (TALIF). Unique to this work is the development of femtosecond-laser-based TALIF (fs-TALIF) that offers a number of advantages over more conventional nanosecond (ns)-pulse-duration laser techniques, such as higher-fidelity quenching rate measurements over a wide pressure range, significantly reduced photolytic interference (including photo-dissociation and photo-ionization), ability to collect two-dimensional images of atomic-species number densities with high spatial resolution aided by higher signal level, and efficient and accurate measurements of atomic-species number densities due to the higher repetition rates of the laser. For full quantification of these advantages, atomic-oxygen TALIF signals are collected from an atmospheric-pressure plasma jet employing both ns- and fs-duration laser-excitation pulses and the results are compared and contrasted.

More than a decade of iodine prophylaxis is needed to eradicate goiter among school age children in a moderately iodine-deficient region.

PubMed

Erdoğan, Murat Faik; Demir, Ozgür; Emral, Rifat; Kamel, Ahmet Nuri; Erdoğan, Gürbüz

2009-03-01

There are many studies regarding the effect of iodine supplementation on goiter, but relatively few reports on the duration of iodine supplementation required to eradicate goiter in iodine-deficient regions. In the current study, we aimed to determine goiter prevalence as determined by sonographic methods, as it relates to changes in median urinary iodine concentrations (UIC) among school age children (SAC), ages 9-11. This study was performed in Ankara, Turkey, before and 5-10 years after mandatory iodination of table salt. Three hundred to 400 SAC from the same primary schools were studied every year by measurement of UIC as part of Turkish Iodine Surveys. Sonographically determined thyroid volume of the SAC had been measured before the mandatory iodination in 1997 and 5-10 years afterward, in 2002 and 2007. The prevalence of goiter in children was evaluated using World Health Organization/International Council for the Control of Iodine Deficiency Disorders recommendations for age and sex. Moderate iodine deficiency was present in 1997 (median UIC, 25.5 microg/L), and it improved to mild iodine deficiency in 2001 (median UIC, 87 microg/L). Sufficient iodine intake (median UIC, 117 microg/L) was achieved by the year 2004. Goiter prevalence was 25% in 1997, 12.3% in 2001, and decreased to 1.3% in 2004. The time required to normalize the prevalence of goiter in SAC living in a moderately iodine-deficient environment was at least a decade. To achieve a goiter rate of less than 5% among SAC, it may require that, as a population, they were born and grew up under conditions of iodine sufficiency.

Nutritional status of iodine in pregnant women in Catalonia (Spain): study on hygiene-dietetic habits and iodine in urine.

PubMed

Prieto, Gemma; Torres, Maria Teresa; Francés, Lidia; Falguera, Gemma; Vila, Lluis; Manresa, Josep María; Casamitjana, Roser; Barrada, Juan Ramón; Acera, Amèlia; Guix, Dolors; Torrent, Anna; Grau, Josep; Torán, Pere

2011-03-08

It is a priority to achieve an adequate nutritional status of iodine during pregnancy since iodine deficiency in this population may have repercussions on the mother during both gestation and post partum as well as on the foetus, the neonate and the child at different ages. According to the WHO, iodine deficiency is the most frequent cause of mental retardation and irrreversible cerebral lesions around the world. However, few studies have been published on the nutritional status of iodine in the pregnant population within the Primary Care setting, a health care level which plays an essential role in the education and control of pregnant women. Therefore, the aim of the present study is: 1.- To know the hygiene-dietetic habits related to the intake of foods rich in iodine and smoking during pregnancy. 2.- To determine the prevalence of iodine deficiency and the factors associated with its appearance during pregnancy. We will perform a cluster randomised, controlled, multicentre trial. Randomisation unit: Primary Care Team. 898 pregnant women over the age of 17 years attending consultation to a midwife during the first trimester of pregnancy in the participating primary care centres. consumption of iodine-rich foods and iodine deficiency. Points of assessment: each trimester of the gestation. group education during the first trimester of gestation on healthy hygiene-dietetic habits and the importance of an adequate iodine nutritional status. descriptive analysis of all variables will be performed as well as multilevel logistic regression. All analyses will be done carried out on an intention to treat basis and will be fitted for potential confounding factors and variables of clinical importance. Evidence of generalised iodine deficiency during pregnancy could lead to the promotion of interventions of prevention such as how to improve and intensify health care educational programmes for pregnant women. ClinicalTrials.gov: NCT01301768.

Helium Tagging Infrared Photodissociation Spectroscopy of Reactive Ions.

PubMed

Roithová, Jana; Gray, Andrew; Andris, Erik; Jašík, Juraj; Gerlich, Dieter

2016-02-16

The interrogation of reaction intermediates is key for understanding chemical reactions; however their direct observation and study remains a considerable challenge. Mass spectrometry is one of the most sensitive analytical techniques, and its use to study reaction mixtures is now an established practice. However, the information that can be obtained is limited to elemental analysis and possibly to fragmentation behavior, which is often challenging to analyze. In order to extend the available experimental information, different types of spectroscopy in the infrared and visible region have been combined with mass spectrometry. Spectroscopy of mass selected ions usually utilizes the powerful sensitivity of mass spectrometers, and the absorption of photons is not detected as such but rather translated to mass changes. One approach to accomplish such spectroscopy involves loosely binding a tag to an ion that will be removed by absorption of one photon. We have constructed an ion trapping instrument capable of reaching temperatures that are sufficiently low to enable tagging by helium atoms in situ, thus permitting infrared photodissociation spectroscopy (IRPD) to be carried out. While tagging by larger rare gas atoms, such as neon or argon is also possible, these may cause significant structural changes to small and reactive species, making the use of helium highly beneficial. We discuss the "innocence" of helium as a tag in ion spectroscopy using several case studies. It is shown that helium tagging is effectively innocent when used with benzene dications, not interfering with their structure or IRPD spectrum. We have also provided a case study where we can see that despite its minimal size there are systems where He has a huge effect. A strong influence of the He tagging was shown in the IRPD spectra of HCCl(2+) where large spectral shifts were observed. While the presented systems are rather small, they involve the formation of mixtures of isomers. We have therefore

Geographical distribution of drinking-water with high iodine level and association between high iodine level in drinking-water and goitre: a Chinese national investigation.

PubMed

Shen, Hongmei; Liu, Shoujun; Sun, Dianjun; Zhang, Shubin; Su, Xiaohui; Shen, Yanfeng; Han, Hepeng

2011-07-01

Excessive iodine intake can cause thyroid function disorders as can be caused by iodine deficiency. There are many people residing in areas with high iodine levels in drinking-water in China. The main aim of the present study was to map the geographical distribution of drinking-water with high iodine level in China and to determine the relationship between high iodine level in drinking-water and goitre prevalence. Iodine in drinking-water was measured in 1978 towns of eleven provinces in China, with a total of 28,857 water samples. We randomly selected children of 8-10 years old, examined the presence of goitre and measured their urinary iodine in 299 towns of nine provinces. Of the 1978 towns studied, 488 had iodine levels between 150 and 300 μg/l in drinking-water, and in 246 towns, the iodine level was >300 μg/l. These towns are mainly distributed along the original Yellow River flood areas, the second largest river in China. Of the 56 751 children examined, goitre prevalence was 6.3 % in the areas with drinking-water iodine levels of 150-300 μg/l and 11.0 % in the areas with drinking-water iodine >300 μg/l. Goitre prevalence increased with water and urinary iodine levels. For children with urinary iodine >1500 μg/l, goitre prevalence was 3.69 times higher than that for those with urinary iodine levels of 100-199 μg/l. The present study suggests that drinking-water with high iodine levels is distributed in eleven provinces of China. Goitre becomes more prevalent with the increase in iodine level in drinking-water. Therefore, it becomes important to prevent goitre through stopping the provision of iodised salt and providing normal drinking-water iodine through pipelines in these areas in China.

A new study of iodine complexes of oxidized gum arabic: An interaction between iodine monochloride and aldehyde groups.

PubMed

Ali, Akbar; Ganie, Showkat Ali; Mazumdar, Nasreen

2018-01-15

Gum arabic, a plant polysaccharide was oxidized with periodate to produce aldehyde groups by the cleavage of diols present in the sugar units. The oxidized gum was then iodinated with iodine monochloride (ICl) and the interaction between electrophilic iodine, I + and reactive carbonyl groups of the modified gum was studied.Results of titrimetric estimation performed to determine the extent of oxidation and aldehyde content in the oxidized gum showed that degree of oxidation ranged between 19.68-50.19% which was observed to increase with periodate concentration; the corresponding aldehyde content was calculated to be 5.15-40.42%. Different strengths of ICl were used to iodinate the oxidized gum and the iodine content of the complexes varied from 6.11-11.72% as determined by iodometric titration. Structure elucidation of the iodine complexes conclusively established the attachment of ICl molecules to CHO groups. A reaction scheme has been proposed suggesting an electrophilic addition of the reagent to the aldehyde groups, a mechanism that was also supported by iodide ion release studies. Copyright © 2017 Elsevier Ltd. All rights reserved.

Experimental Performance of a Single-Mode Ytterbium-doped Fiber Ring Laser with Intracavity Modulator

NASA Technical Reports Server (NTRS)

Numata, Kenji; Camp, Jordan

2012-01-01

We have developed a linearly polarized Ytterbium-doped fiber ring laser with a single longitudinal mode output at 1064 run. A fiber-coupled intracavity phase modulator ensured mode-hop free operation and allowed fast frequency tuning. The fiber laser was locked with high stability to an iodine-stabilized laser, showing a frequency noise suppression of a factor approx 10 (exp 5) at 1 mHz

Excessive iodine intake does not increase the recurrence rate of graves' disease after withdrawal of the antithyroid drug in an iodine-replete area.

PubMed

Park, Sun Mi; Cho, Yoon Young; Joung, Ji Young; Sohn, Seo Young; Kim, Sun Wook; Chung, Jae Hoon

2015-03-01

The relationship between iodine intake and effects of antithyroid drugs (ATD) for Graves' disease, especially in iodine-deficient areas, has been demonstrated in many studies. However, it was not clear how chronic high iodine intake influenced the effectiveness of ATD in an iodine-replete area. This study aimed to clarify the effect of iodine intake on clinical outcomes of Graves' disease after discontinuation of ATD in Korea, an iodine-replete area. A total of 142 patients with Graves' disease who visited the outpatient clinic regularly and stopped their ATD between October 2011 and April 2013 were enrolled in our study. Urinary iodine concentration (UIC) was measured just before and after the discontinuation of ATD. Median UIC was not significantly different between the remission and relapse groups, as well as among the four treatment groups (group 1, remission after initial treatment; group 2, remission after repeated treatment; group 3, early relapse within a year; group 4, late relapse after a year). Remission rates did not show a significant difference between the excessive iodine intake (UIC ≥300 μg/l) and average iodine intake groups (UIC <300 μg/l). The present study suggests that excessive iodine intake does not have an effect on the clinical outcomes of Graves' disease in an iodine-replete area, and therefore diet control with iodine restriction might not be necessary in the management of Graves' disease.

Survey of iodine nutritional status in 2011, Zhejiang, China.

PubMed

Mao, Guangming; Ding, Gangqiang; Lou, Xiaoming; Zhang, Ronghua; Zheng, Pai; Mo, Zhe; Wang, Xiaofeng; Zhu, Wenming; Zhou, Jinshui; Gu, Fang

2015-01-01

Universal salt iodization (USI) was introduced in China in 1995, but whether the iodine status is optimal is questionable. This study was conducted to assess the iodine nutrition among Zhejiang population in coastal regions in China. A cross-sectional survey for iodine nutritional status was conducted with general population (n=10,350), including pregnant and lactating women (n=450 each) selected by stratified multistage sampling. Iodine content in drinking water, table salt and urine, were determined using arsenic-cerium catalytic spectrophotometry, the direct titration and the arsenic-cerium catalytic spectrophotometry, respectively, and daily iodine intake was estimated by 3 days of 24-hour recall method. The median iodine content in drinking water was 2.46 μg/L, Zhejiang belonged to the region of iodine deficiency in outer environment according to China standard. The median iodine content in table salt was 27.9 mg/kg, conforming to the standard requirements; the household coverage rate of qualified iodized salt reached 76.8%, which does not reach the standard requirement of WHO >90%. The dietary iodine intake of a reference individual averaged 379 μg/d, which indicated that the current iodine intake in diet was appropriate. In addition, the median urinary iodine concentration (UIC) was 162 μg/L in general population, and 130 μg/L in pregnant women, which didn't reach the standard requirements. The current dietary iodine intake in Zhejiang was generally sufficient and safe, but there is a risk of iodine deficiency among pregnant women and the population who do not consume iodized salt.

The Iodine Status of Queensland Preschool Children After the Introduction of Mandatory Iodine Fortification in Bread: An Exploratory Study Using a Convenience Sample.

PubMed

Samidurai, A J; Ware, R S; Davies, P S W

2017-01-01

Introduction Appropriate dietary iodine is essential for thyroid hormone synthesis, especially in young children. Following an iodine fortification in bread initiative, approximately 6 % of Australian preschool children were expected to have an excessive iodine status. The aim of this study was to document the current iodine status of preschool children using urinary iodine concentration (UIC) as a biomarker of iodine intake. Methods A convenience sample of fifty-one preschool children, aged 2-3 years, were recruited from south east Queensland. UIC was ascertained from spot morning and afternoon urine samples collected on two consecutive days and food frequency questionnaires were completed for each participant. Dietary iodine intake was extrapolated from UIC assuming 90 % of dietary iodine is excreted in urine and a urine volume of 0.5 L/day. Results A median UIC of 223.3 μg/L was found. The calculated median dietary iodine intake was 124.8 μg/day (SD 47.0) with 9.8 % of samples above the upper level of 200 μg for dietary iodine for children within this age group. No foods were associated with UIC. Discussion Limited by sample size and recruitment strategies, no association was found between usual food intake and UIC. Extrapolated dietary iodine intake indicated that children within this cohort consumed adequate amounts of dietary iodine, although the number of children consuming above the upper limit of 300 μg/day was almost double of expected. The development of a UIC criteria to assess appropriate parameters for varying degrees of iodine status is required for the monitoring of iodine nutrition in this vulnerable age group.

Source And Sink Of Iodine For Drinking Water

NASA Technical Reports Server (NTRS)

Sauer, Richard L.; Flanagan, David T.; Gibbons, Randall E.

1991-01-01

Proposed system for controlling concentration of iodine in potable water exploits temperature dependence of equilibrium partition of iodine between solution in water and residence in ion-exchange resin. Used to maintain concentration of iodine sufficient to kill harmful microbes, but not so great to make water unpalatable. Requires little attention, yet controls concentration of iodine more precisely than iodination and deiodination by manual techniques. Conceived for use aboard spacecraft, system has terrestrial applications in regions where water must be kept potable, resupply difficult, and system must operate largely unattended.

Automated iodine monitor system. [for aqueous solutions

NASA Technical Reports Server (NTRS)

1973-01-01

The feasibility of a direct spectrophotometric measurement of iodine in water was established. An iodine colorimeter, was built to demonstrate the practicality of this technique. The specificity of this method was verified when applied to an on-line system where a reference solution cannot be used, and a preliminary design is presented for an automated iodine measuring and controlling system meeting the desired specifications. An Automated iodine monitor/controller system based on this preliminary design was built, tested, and delivered to the Johnson Space Center.

Toward understanding the dissociation of I2 in chemical oxygen-iodine lasers: Combined experimental and theoretical studies

NASA Astrophysics Data System (ADS)

Waichman, K.; Rybalkin, V.; Katz, A.; Dahan, Z.; Barmashenko, B. D.; Rosenwaks, S.

2007-07-01

The dissociation of I2 molecules at the optical axis of a supersonic chemical oxygen-iodine laser (COIL) was studied via detailed measurements and three-dimensional computational fluid dynamics calculations. The measurements, briefly reported in a recent paper [Rybalkin et al., Appl. Phys. Lett. 89, 021115 (2006)] and reanalyzed in detail here, revealed that the number N of consumed O2(aΔg1) molecules per dissociated I2 molecule depends on the experimental conditions: it is 4.5±0.4 for typical conditions and I2 densities applied for optimal operation of the COIL but increases at lower I2 densities. Comparing the measurements and the calculations enabled critical examination of previously proposed dissociation mechanisms and suggestion of a mechanism consistent with the experimental and theoretical results obtained in a supersonic COIL for the gain, temperature, I2 dissociation fraction, and N at the optical axis. The suggested mechanism combines the recent scheme of Azyazov and Heaven [AIAA J. 44, 1593 (2006)], where I2(A'Π2u3), I2(AΠ1u3), and O2(aΔg1,v) are significant dissociation intermediates, with the "standard" chain branching mechanism of Heidner III et al. [J. Phys. Chem. 87, 2348 (1983)], involving I(P1/22) and I2(XΣg +1,v).

PHYSICAL EFFECTS OCCURRING DURING GENERATION AND AMPLIFICATION OF LASER RADIATION: Efficient solutions for low-temperature singlet-oxygen generators

NASA Astrophysics Data System (ADS)

Igoshin, Valerii I.; Karyshev, V. D.; Katulin, V. A.; Kirilin, A. V.; Kisletsov, A. V.; Konnov, S. A.; Kupriyanov, N. L.; Medvedev, A. M.; Nadezhina, T. N.

1989-02-01

Experimental investigations were made of the physicochemical characteristics of the active solutions for a chemical generator in an oxygen-iodine laser. A strong temperature dependence of the viscosity of the solution was observed. The influence of this factor on the operation of the singlet-oxygen generator and the laser is discussed. The cyclic operation of a laser with efficient neutralization of the reagents and the addition of an alkali is simulated. It is shown that hydrogen peroxide may be 50% utilized when the temperature of the solution is no higher than - 30 °C. A method of preparing a solution for an iodine laser with a low freezing point (between - 30 °C and - 40 °C) is developed. It is shown that an aqueous solution of hydrogen peroxide with a concentration of 25-40% is suitable.

Multiple product pathways in photodissociation of nitromethane at 213 nm

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sumida, Masataka; Kohge, Yasunori; Yamasaki, Katsuyoshi

2016-02-14

In this paper, we present a photodissociation dynamics study of nitromethane at 213 nm in the π → π{sup *} transition. Resonantly enhanced multiphoton ionization spectroscopy and ion-imaging were applied to measure the internal state distributions and state-resolved scattering distributions of the CH{sub 3}, NO(X {sup 2}Π, A {sup 2}Σ{sup +}), and O({sup 3}P{sub J}) photofragments. The rotationally state-resolved scattering distribution of the CH{sub 3} fragment showed two velocity components, of which the slower one decreased the relative intensity as the rotational and vibrational excitations. The translational energy distribution of the faster CH{sub 3} fragment indicated the production of themore » NO{sub 2} counter-product in the electronic excited state, wherein 1 {sup 2}B{sub 2} was the most probable. The NO(v = 0) fragment exhibited a bimodal translational energy distribution, whereas the NO(v = 1 and 2) fragment exhibited a single translational energy component with a relatively larger internal energy. The translational energy of a portion of the O({sup 3}P{sub J}) photofragment was found to be higher than the one-photon dissociation threshold, indicating the two-photon process involved. The NO(A {sup 2}Σ{sup +}) fragment, which was detected by ionization spectroscopy via the Rydberg ←A {sup 2}Σ{sup +} transition, also required two-photon energy. These experimental data corroborate the existence of competing photodissociation product pathways, CH{sub 3} + NO{sub 2},CH{sub 3} + NO + O,CH{sub 3}O + NO, and CH{sub 3}NO + O, following the π → π{sup *} transition. The origins of the observed photofragments are discussed in this report along with recent theoretical studies and previous dynamics experiments performed at 193 nm.« less

Iodine nutritional status in pregnant women of two historically different iodine-deficient areas of Catalonia, Spain.

PubMed

Vila, Lluis; Serra-Prat, Mateu; de Castro, Alfonso; Palomera, Elisabet; Casamitjana, Roser; Legaz, Gustavo; Barrionuevo, Celia; Muñoz, José A; García, Ana J; Lal-Trehan, Sanjay; García, Amparo; Durán, Josep; Puig-Domingo, Manel

2011-10-01

Catalonia (Spain) has a historically worse situation of mild iodine deficiency in the Pyrenees Mountains compared with the coastal region. The aim of this study was to evaluate the current iodine status in pregnant women living in these two areas. An epidemiologic prospective survey included 267 consecutive pregnancies in the Catalan mountains (n = 139) and coast (n = 128) studied during the first trimester; an additional subset of 135 women from the initial cohort was available for evaluation in the third trimester. Urinary iodine (UI) was measured, and questionnaires to determine iodized salt and sea fish consumption and potassium iodide supplementation were administered. The median UI in the first trimester was 163 μg/L for the entire cohort, with differences between mountain and coastal regions (209 versus 142 μg/L, P = 0.007). The highest prevalence of iodized salt consumption was in the mountain area (58% versus 36.4%, P < 0.001). For the entire group, a higher median UI was found in iodized salt consumers compared with non-consumers (193 versus 134 μg/L, P < 0.001). In the third trimester, an increase of median UI was seen in those to whom iodine supplements were given during pregnancy (190 versus 154 μg/L, P = 0.015). A reversal in the historically iodine-deficient situation was observed in the Catalan Pyrenees compared with the coastal area, with a globally acceptable iodine status in pregnant women of the two geographic locations. Iodized salt consumption seems to have contributed to maintaining an acceptable iodine status in this population. Copyright © 2011 Elsevier Inc. All rights reserved.

The photodissociation dynamics of alkyl radicals

DOE Office of Scientific and Technical Information (OSTI.GOV)

Giegerich, Jens; Fischer, Ingo, E-mail: ingo.fischer@uni-wuerzburg.de

2015-01-28

The photodisscociation dynamics of the alkyl radicals i-propyl (CH(CH{sub 3}){sub 2}) and t-butyl (C(CH{sub 3}){sub 3}) are investigated by H-atom photofragment imaging. While i-propyl is excited at 250 nm, the photodynamics of t-butyl are explored over a large energy range using excitation wavelengths between 347 nm and 233 nm. The results are compared to those obtained previously for ethyl, CH{sub 3}CH{sub 2}, and to those reported for t-butyl using 248 nm excitation. The translational energy (E{sub T}) distribution of the H-atom photofragments is bimodal and appears rather similar for all three radicals. The low E{sub T} part of the distributionmore » shows an isotropic photofragment angular distribution, while the high E{sub T} part is associated with a considerable anisotropy. Thus, for t-butyl, two H-atom loss channels of roughly equal importance have been identified in addition to the CH{sub 3}-loss channel reported previously. A mechanism for the photodissociation of alkyl radicals is suggested that is based on interactions between Rydberg- and valence states.« less

Current iodine nutrition status and progress toward elimination of iodine deficiency disorders in Jazan, Saudi Arabia

PubMed Central

2012-01-01

Background The term iodine deficiency disorders (IDD) refers to all the effects of iodine deficiency on growth and development in human and animal populations that can be prevented by correction of the iodine deficiency. The objective of this paper was to determine the iodine nutrition status among schoolchildren in the Jazan Region of the Kingdom of Saudi Arabia (KSA), by measuring urinary iodine concentrations and by clinical assessments of goiter rate. Methods A school-based cross-sectional survey was conducted in the Jazan region of southwestern KSA from May to November 2010. A total of 311 children, aged 6–13 years, drawn from 12 schools, were selected by a three-stage cluster random sampling method. Data on sociodemographic characteristics were collected using a structured questionnaire. Urine samples were collected and physical examinations were conducted to determine the presence or absence of goiter. Data were analyzed using SPSS version 17.0. Chi square and independent t-tests were used for proportions and mean comparisons between groups. Results Out of 360 selected children, 311 were examined. There were 131 males (42%) and 180 females (58%). The median urinary iodine concentration (UIC) of the study group was 421 μg/L. The study population proportion with UIC > 300 μg/L was 74% with a higher proportion among males and urban populations. The proportion of children with UIC of 100–300 μg/L was only 21% and was significantly higher among females compared with males (p < 0.001). Only about 3% of the children had a median UIC less than 50 μg/L. The prevalence of total goiter rate (TGR) among the sample of schoolchildren in Jazan was 11%, with significant variations between rural and urban populations and by gender. Conclusions The present study demonstrates a remarkable achievement in Universal Salt Iodization (USI) and IDD elimination goals in the Jazan area. However, UIC levels reflect excessive iodine intake and may put the population at risk of

21 CFR 520.1157 - Iodinated casein tablets.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Iodinated casein tablets. 520.1157 Section 520...) ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS ORAL DOSAGE FORM NEW ANIMAL DRUGS § 520.1157 Iodinated casein tablets. (a) Specifications. Each 1-gram tablet contains 25 milligrams of iodinated casein. (b) Sponsor...

21 CFR 520.1157 - Iodinated casein tablets.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 21 Food and Drugs 6 2011-04-01 2011-04-01 false Iodinated casein tablets. 520.1157 Section 520...) ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS ORAL DOSAGE FORM NEW ANIMAL DRUGS § 520.1157 Iodinated casein tablets. (a) Specifications. Each 1-gram tablet contains 25 milligrams of iodinated casein. (b) Sponsor...

Protein relaxation without a geminate phase in nanosecond photodissociated CO carp hemoglobin

NASA Astrophysics Data System (ADS)

Loupiac, Camille; Kruk, Nicolay; Valat, Pierre; Alpert, Bernard

1999-03-01

Transient heme-protein interactions upon passing from ligated to deligated carp hemoglobin were observed through time-resolved optical spectra following nanosecond CO photodissociation. The spectral evolution of the heme, in the nanosecond and microsecond time ranges, shows a protein conformational relaxation and the absence of a geminate CO recombination in carp hemoglobin. The comparison of the phenomena in carp and human hemoglobin implies that the physical basis of the geminate rebinding in human hemoglobin should involve an out-of-equilibrium protein conformation, close to a dissipative structure defined by the thermodynamics of Prigogine.

[Photodissociation of Acetylene and Acetone using Step-Scan Time-Resolved FTIR Emission Spectroscopy

NASA Technical Reports Server (NTRS)

McLaren, Ian A.; Wrobel, Jacek D.

1997-01-01

The photodissociation of acetylene and acetone was investigated as a function of added quenching gas pressures using step-scan time-resolved FTIR emission spectroscopy. Its main components consist of Bruker IFS88, step-scan Fourier Transform Infrared (FTIR) spectrometer coupled to a flow cell equipped with Welsh collection optics. Vibrationally excited C2H radicals were produced from the photodissociation of acetylene in the unfocused experiments. The infrared (IR) emission from these excited C2H radicals was investigated as a function of added argon pressure. Argon quenching rate constants for all C2H emission bands are of the order of 10(exp -13)cc/molecule.sec. Quenching of these radicals by acetylene is efficient, with a rate constant in the range of 10(exp -11) cc/molecule.sec. The relative intensity of the different C2H emission bands did not change with the increasing argon or acetylene pressure. However, the overall IR emission intensity decreased, for example, by more than 50% when the argon partial pressure was raised from 0.2 to 2 Torr at fixed precursor pressure of 160mTorr. These observations provide evidence for the formation of a metastable C2H2 species, which are collisionally quenched by argon or acetylene. Problems encountered in the course of the experimental work are also described.

[Application of iodine metabolism analysis methods in thyroid diseases].

PubMed

Han, Jian-hua; Qiu, Ling

2013-08-01

The main physiological role of iodine in the body is to synthesize thyroid hormone. Both iodine deficiency and iodine excess can lead to severe thyroid diseases. While its role in thyroid diseases has increasingly been recognized, few relevant platforms and techniques for iodine detection have been available in China. This paper summarizes the advantages and disadvantages of currently iodine detection methods including direct titration, arsenic cerium catalytic spectrophotometry, chromatography with pulsed amperometry, colorimetry based on automatic biochemistry, inductively coupled plasma mass spectrometry, so as to optimize the iodine nutrition for patients with thyroid diseases.

Bond-selective photodissociation of partially deuterated ammonia molecules: Photodissociations of vibrationally excited NHD2 in the 5νNH state and NH2D in the 5νND state

NASA Astrophysics Data System (ADS)

Akagi, Hiroshi; Yokoyama, Keiichi; Yokoyama, Atsushi

2004-03-01

Ultraviolet photodissociation of NHD2 excited to the fourth overtone state of the NH stretching mode (5νNH) and NH2D excited to that of the ND stretching mode (5νND) has been investigated by using a crossed laser and molecular beams method. Branching ratio between the NH and ND bond dissociations has been determined by utilizing a (2+1) resonance enhanced multiphoton ionization scheme of H and D atoms. For the photolysis of NHD2 in the 5νNH state, the NH dissociation cross section is 5.1±1.4 times as large as the ND dissociation cross section per bond. On the other hand, for the photolysis of NH2D in the 5νND state, the ratio of the NH dissociation cross section per bond to the ND dissociation cross section decreases to 0.68±0.16. In comparison with the branching ratios for the photolysis of vibrationally unexcited NH2D and NHD2 [Koda and Back, Can. J. Chem. 55, 1380 (1977)], the present results indicate that the excitation of the NH stretching mode enhances the NH dissociation with ca. two times larger NH/ND branching ratio, whereas the excitation of the ND stretching mode results in the preferential ND dissociation with ca. 3-4 times larger ND/NH branching ratio than that for the vibrational ground states. The mechanism of the bond-selective enhancement has been discussed in terms of the energetics and dynamics of wave packet.

DFT/TDDFT study on the photodissociation mechanism of the original monascus red and orange pigments

NASA Astrophysics Data System (ADS)

Liu, Yi; Wu, Li; Lv, Qingzhang

2015-06-01

The weak photostability has to some extent restricted the wide utilization of monascus pigments in food industries, and their photobleaching mechanism is unclear yet. Density functional theory and time-dependent density functional theory at B3LYP/6-311+G(d,p) level have been performed to optimize the geometries of ground states, single and triplet excited-states of the original monascus red and orange pigments, the possible photodissociation mechanism of which is analyzed according to the calculated data. It is the break of the chromophores, conjugated π bonds which has induced their decoloration. The photodissociation of these pigments involves three steps, excitation of the large conjugated π system, water addition to the singlet or triplet excited-state, and Norrish type I photochemical cleavage reactions of the side chains. The former two steps are much more important steps which have led to the destruction of the chromophores and the fading of the four original monascus red and orange pigments. According to the photobleaching mechanism obtained, one could find some solutions to enhance the photostability of these monascus colorants during the food processing process and extend the shelf life of the foods added with monascus pigments.

Research Studies on Radiative Collision Lasers

DTIC Science & Technology

1980-06-01

34Branching Ratios for TlBr Photodissocia- tion with 2660 X Radiation." Abstract: Selective molecular photodi:ssociation as a pumping mechanism to invert...following the flash photolysis of CF I. In the present work we examine the selective 3 photodissociation of TlBr into the Tl(6p 2 P3 / 2 ) metastable state

Radioactive Iodine Treatment for Hyperthyroidism

MedlinePlus

... other parts of the body. RAI, also called iodine 131 (I-131), is given as a single-dose capsule or liquid. Most often, you will not need a hospital stay. It can take 6 to ... Know? Radioactive iodine is a generally safe treatment that can cure ...

Lifestyle factors related to iodine intakes in French adults.

PubMed

Valeix, Pierre; Faure, Patrice; Péneau, Sandrine; Estaquio, Carla; Hercberg, Serge; Bertrais, Sandrine

2009-12-01

To assess dietary iodine intakes among adults and to investigate the relationships of dietary, lifestyle, demographic and geographical characteristics with dietary iodine status. Adequacy of iodine intakes was also assessed. Cross-sectional study. Linear regression analyses and logistic regression modelling were used to determine correlates of iodine intakes. Usual iodine mean intake was calculated by averaging six 24 h dietary records completed over a 2-year period. Females aged 35-60 years (n 2962) and males aged 45-60 years (n 2117) living in France and who participated in the SU.VI.MAX study. Iodine intakes ranged from 30.0 to 446.3 microg/d. The median iodine intake was 150.7 microg/d for males and 131.4 microg/d for females. High-level (97.5th percentile) intakes were 273.4 microg/d for males and 245.0 microg/d for females. Overall, 8.5 % of males and 20.3 % of females had intakes <100 microg/d (P < 0.001). Alcohol drinkers and smokers tended to have lower iodine intakes than abstainers or non-smokers. Regular physical activity and both intermediate and high education levels were associated with a lower risk of iodine intake of <150 microg/d. For both males and females there were significant overall regional differences (P < 0.001) in multivariate-adjusted iodine intakes, with higher adjusted iodine intakes in Brittany and Normandy than in the north-eastern region. Our data show a borderline low iodine intake in this middle-aged French population. However, differences in iodine intakes may contribute to explaining only a small part of the effects of sex and age on thyroid disease incidence.

Excessive Iodine Intake Does Not Increase the Recurrence Rate of Graves' Disease after Withdrawal of the Antithyroid Drug in an Iodine-Replete Area

PubMed Central

Park, Sun Mi; Cho, Yoon Young; Joung, Ji Young; Sohn, Seo Young; Kim, Sun Wook; Chung, Jae Hoon

2015-01-01

Background and Objectives The relationship between iodine intake and effects of antithyroid drugs (ATD) for Graves' disease, especially in iodine-deficient areas, has been demonstrated in many studies. However, it was not clear how chronic high iodine intake influenced the effectiveness of ATD in an iodine-replete area. This study aimed to clarify the effect of iodine intake on clinical outcomes of Graves' disease after discontinuation of ATD in Korea, an iodine-replete area. Methods A total of 142 patients with Graves' disease who visited the outpatient clinic regularly and stopped their ATD between October 2011 and April 2013 were enrolled in our study. Urinary iodine concentration (UIC) was measured just before and after the discontinuation of ATD. Results Median UIC was not significantly different between the remission and relapse groups, as well as among the four treatment groups (group 1, remission after initial treatment; group 2, remission after repeated treatment; group 3, early relapse within a year; group 4, late relapse after a year). Remission rates did not show a significant difference between the excessive iodine intake (UIC ≥300 μg/l) and average iodine intake groups (UIC <300 μg/l). Conclusions The present study suggests that excessive iodine intake does not have an effect on the clinical outcomes of Graves' disease in an iodine-replete area, and therefore diet control with iodine restriction might not be necessary in the management of Graves' disease. PMID:25960960

First application of an online method for quantification of maritime molecular iodine and hypoiodic acid in maritime aerosol during PEGASO cruise

NASA Astrophysics Data System (ADS)

Götz, Sven; Dall'Osto, Manuel; Simó, Rafel; Hoffmann, Thosten

2015-04-01

The atmospheric chemistry of iodine is important in multiple ways. The focus lies on the ability to influence the oxidizing capacity of the atmosphere, i.e. by destruction of ozone, and the formation of iodine oxide particles (IOP), i.e. the influence on condensation nuclei (CCN). Using a variation of techniques, like differential optical absorption spectroscopy (DOAS), laser-induced fluorescence (LIF), inductively coupled plasma mass spectrometry (ICP-MS) and atmospheric pressure chemical ionization with tandem mass spectrometry (APCI-MS/MS), the reactive iodine species of atomic iodine (I), molecular iodine (I2), iodine monoxide (IO) and iodine dioxide (OIO) have all been detected in the atmosphere from Antarctica to the equatorial marine boundary layer (MBL). In the past few years there have been active research on IO, especially after revealing significant levels in open ocean measurements, and higher iodine oxides. In addition to atmospheric measurements, significant developments in laboratory kinetics, photochemistry and heterogeneous chemistry of iodine species have been accomplished. [1] Here we introduce the first field application of an online-method for detecting gaseous molecular iodine and HOI, which is a further development of a technique [2] based on selective photolytic dissociation, followed by oxidization and particle formation of iodine compounds. The particles are than size-segregated and detected by a scanning mobility particle sizer (SMPS) system. Initial IOP forming is performed in a reaction chamber providing specific wavelengths according to corresponding bond dissociation thresholds. Additionally offline sampling of iodine and iodine containing interhalogenes with coated diffusion denuders [3] were carried out throughout the cruise to compare both methods after analysis with GC/MS. Furthermore filter samples were taken to perform non-target analysis of organic compounds by UHPLC/ESI(+/-)-HR-MS. Preliminary results of iodine related

Computation of iodine species concentrations in water

NASA Technical Reports Server (NTRS)

Schultz, John R.; Mudgett, Paul D.; Flanagan, David T.; Sauer, Richard L.

1994-01-01

During an evaluation of the use of iodine as a water disinfectant and the development of methods for measuring various iodine species in water onboard Space Freedom, it became necessary to compute the concentration of the various species based on equilibrium principles alone. Of particular concern was the case when various amounts of iodine, iodide, strong acid, and strong base are added to water. Such solutions can be used to evaluate the performance of various monitoring methods being considered. The authors of this paper present an overview of aqueous iodine chemistry, a set of nonlinear equations which can be used to model the above case, and a computer program for solving this system of equations using the Newton-Raphson method. The program was validated by comparing results over a range of concentrations and pH values with those previously presented by Gottardi for a given pH. Use of this program indicated that there are multiple roots to many cases and selecting an appropriate initial guess is important. Comparison of program results with laboratory results for the case when only iodine is added to water indicates the program gives high pH values for the iodine concentrations normally used for water disinfection. Extending the model to include the effects of iodate formation results in the computer pH values being closer to those observed, but the model with iodate does not agree well for the case in which base is added in addition to iodine to raise the pH. Potential explanations include failure to obtain equilibrium conditions in the lab, inaccuracies in published values for the equilibrium constants, and inadequate model of iodine chemistry and/or the lack of adequate analytical methods for measuring the various iodine species in water.

Disposal of radioactive iodine in space

NASA Technical Reports Server (NTRS)

Burns, R. E.; Defield, J. G.

1978-01-01

The possibility of space disposal of iodine waste from nuclear power reactors is investigated. The space transportation system utilized relies upon the space shuttle, a liquid hydrogen/liquid oxygen orbit transfer vehicle, and a solid propellant final stage. The iodine is assumed to be in the form of either an iodide or an iodate, and calculations assume that the final destination is either solar orbit or solar system escape. It is concluded that space disposal of iodine is feasible.

Hypothyroidism following iodine-131 therapy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hays, M.T.

1982-02-01

A teaching editorial dealing with the hypothyroidism side effect of Iodine-131 radiotherapy is presented. The author reviews two articles in this issue of the Journal of Nuclear Medicine on the subject, discusses Graves' disease, Iodine 125 radiotherapy, and the patient-physician relationship when dealing with the problem. (JMT)

Nutritional status of iodine in pregnant women in Catalonia (Spain): study on hygiene-dietetic habits and iodine in urine

PubMed Central

2011-01-01

Background It is a priority to achieve an adequate nutritional status of iodine during pregnancy since iodine deficiency in this population may have repercussions on the mother during both gestation and post partum as well as on the foetus, the neonate and the child at different ages. According to the WHO, iodine deficiency is the most frequent cause of mental retardation and irrreversible cerebral lesions around the world. However, few studies have been published on the nutritional status of iodine in the pregnant population within the Primary Care setting, a health care level which plays an essential role in the education and control of pregnant women. Therefore, the aim of the present study is: 1.- To know the hygiene-dietetic habits related to the intake of foods rich in iodine and smoking during pregnancy. 2.- To determine the prevalence of iodine deficiency and the factors associated with its appearance during pregnancy. Methods/design We will perform a cluster randomised, controlled, multicentre trial. Randomisation unit: Primary Care Team. Study population: 898 pregnant women over the age of 17 years attending consultation to a midwife during the first trimester of pregnancy in the participating primary care centres. Outcome measures: consumption of iodine-rich foods and iodine deficiency. Points of assessment: each trimester of the gestation. Intervention: group education during the first trimester of gestation on healthy hygiene-dietetic habits and the importance of an adequate iodine nutritional status. Statistical analysis: descriptive analysis of all variables will be performed as well as multilevel logistic regression. All analyses will be done carried out on an intention to treat basis and will be fitted for potential confounding factors and variables of clinical importance. Discussion Evidence of generalised iodine deficiency during pregnancy could lead to the promotion of interventions of prevention such as how to improve and intensify health care

Method and apparatus for removing iodine from a nuclear reactor coolant

DOEpatents

Cooper, Martin H.

1980-01-01

A method and apparatus for removing iodine-131 and iodine-125 from a liquid sodium reactor coolant. Non-radioactive iodine is dissolved in hot liquid sodium to increase the total iodine concentration. Subsequent precipitation of the iodine in a cold trap removes both the radioactive iodine isotopes as well as the non-radioactive iodine.

Iodine deficiency disorders: contemporary scientific issues.

PubMed

Maberly, G F

1994-08-01

Iodine deficiency is the leading cause of preventable intellectual impairment and is associated with a spectrum of neurologic and developmental pathology. More than one billion people are at risk. The developing fetus, newborn, and young child are the most susceptible to the effects of an iodine-deficient diet. If intervention is not initiated in a timely fashion, the pathophysiologic abnormalities become resistant to treatment and permanent intellectual, neurologic, and somatic deficits result. The technology of iodine deficiency intervention is well established. Iodized salt, the preferred method, is easy to produce, administer in physiologic doses, and is cost effective. The distribution of iodized salt and social marketing are key to a successful iodine deficiency elimination program. In remote regions, iodized oil is a useful interim intervention. However, it is clear that technology is not enough. Any national effort to eliminate iodine deficiency must extend far beyond the Ministry of Health. The program will require the full participation of a range of national government ministries and agencies and the full support and participation of local or regional governments.

Iodine Nutritional Status of School Children in Nauru 2015

PubMed Central

Huang, Chun-Jui; Tseng, Chi-Lung; Chen, Harn-Shen; Garabwan, Chanda; Korovo, Samuela; Tang, Kam-Tsun; Won, Justin Ging-Shing; Hsieh, Chang-Hsun; Wang, Fan-Fen

2016-01-01

Little is known about iodine nutritional status in island countries in the Pacific Ocean. The primary objective of this study was to report for the first time the iodine nutritional status of people in Nauru. In addition, sources of iodine nutrition (i.e., water and salt) were investigated. A school-based cross-sectional survey of children aged 6–12 years was conducted in three primary schools of Nauru. Urinary iodine concentration (UIC) was determined by spot urine samples. Available water and salt samples in Nauru were collected for the measurement of iodine content. A food frequency questionnaire was conducted. The median UIC was 142 μg/L, and 25.2% and 7.4% of the population had median UIC below 100 μg/L and 50 μg/L, respectively. Natural iodine-containing foods such as seaweeds and agar were rare. Iodine was undetectable in Nauruan tank water, filtered tap water, and raindrops. Of the analyzed salt products, five kinds were non-iodized, and three were iodized (iodine content: 15 ppm, 65 ppm, and 68 ppm, respectively). The results indicate that the iodine status in Nauruan school children is adequate. Iodized salt may serve as an important source of iodine nutrition in Nauru. PMID:27563920

Effectiveness of the iodine prophylaxis model adopted in Poland.

PubMed

Szybinski, Z; Golkowski, F; Buziak-Bereza, M; Trofimiuk, M; Przybylik-Mazurek, E; Huszno, B; Bandurska-Stankiewicz, E; Bar-Andziak, E; Dorant, B; Kinalska, I; Lewinski, A; Klencki, M; Rybakowa, M; Sowinski, J; Szewczyk, L; Szponar, L; Wasik, R

2008-04-01

Most of the Polish territory has been classified as an iodine-deficient and endemic goiter area according to the International Council for Control of Iodine Deficiency (ICCIDD) criteria. In 1997 the obligatory model of iodine prophylaxis was implemented. Our investigations were aimed at the effectiveness of iodine prophylaxis in Poland. We assessed urinary iodine excretion and goiter prevalence in 5663 children aged 6-12 yr. The population of children from the same 27 schools was investigated from 1992 to 1994 (1406 girls and 1244 boys) and from 1999 to 2005 (1563 girls and 1450 boys) using identical laboratory and ultrasound methods. We found significant increase in iodine urinary concentration (median 52 microg/l vs 93 microg/l, p<0.001) with accompanying drop in goiter prevalence (29.6% vs 5.2%, p<0.001) after implementation of iodine prophylaxis. Iodine excretion distribution changed significantly after 1997 with an increase in the percentage of children with iodine urinary concentration above 100 microg/l from 10.8% to 45.4%, respectively. A significantly higher iodine urinary concentration was observed in lowlands compared to uplands both before and after implementation of iodine prophylaxis (median, 50 microg/l vs 57 microg/l and 86 microg/l vs 114 microg/l, respectively, p<0.001). The goiter prevalence did not differ between girls and boys from 1992 to 1994 (28.8% vs 30.5%, p=0.35) and 1999 to 2005 (5.5% vs 4.9%, p=0.45). Implementation of the new model of iodine prophylaxis in Poland in 1997 has led to significant increase in iodine urinary concentration and decrease in goiter prevalence among Polish schoolchildren. In the youngest group of children (6-8 yr olds), prevalence of goiter decreased to 3.2%--i.e. below endemic levels.

Iodine status in the Nordic countries - past and present.

PubMed

Nyström, Helena Filipsson; Brantsæter, Anne Lise; Erlund, Iris; Gunnarsdottir, Ingibjörg; Hulthén, Lena; Laurberg, Peter; Mattisson, Irene; Rasmussen, Lone Banke; Virtanen, Suvi; Meltzer, Helle Margrete

2016-01-01

Adequate iodine nutrition is dependent on ground water content, seafood, and, as many countries use iodized cow fodder, dairy products. In most countries, salt fortification programs are needed to assure adequate iodine intake. The objectives are threefold: 1) to describe the past and present iodine situation in the Nordic countries, 2) to identify important gaps of knowledge, and 3) to highlight differences among the Nordic countries' iodine biomonitoring and fortification policies. Historical data are compared with the current situation. The Nordic countries' strategies to achieve recommended intake and urine iodine levels and their respective success rates are evaluated. In the past, the iodine situation ranged from excellent in Iceland to widespread goiter and cretinism in large areas of Sweden. The situation was less severe in Norway and Finland. According to a 1960 World Health Organization (WHO) report, there were then no observations of iodine deficiency in Denmark. In Sweden and Finland, the fortification of table salt was introduced 50-75 years ago, and in Norway and Finland, the fortification of cow fodder starting in the 1950s helped improve the population's iodine status due to the high intake of milk. In Denmark, iodine has been added to household salt and salt in bread for the past 15 years. The Nordic countries differ with regard to regulations and degree of governmental involvement. There are indications that pregnant and lactating women, the two most vulnerable groups, are mildly deficient in iodine in several of the Nordic countries. The Nordic countries employ different strategies to attain adequate iodine nutrition. The situation is not optimal and is in need of re-evaluation. Iodine researchers, Nordic national food administrations, and Nordic governmental institutions would benefit from collaboration to attain a broader approach and guarantee good iodine health for all.