scholarly journals The influence of chemical parameters on the in-situ metal carbonyl complex formation studied with the fast on-line reaction apparatus (FORA)

2021 ◽  
Vol 109 (4) ◽  
pp. 243-260 ◽  
Author(s):  
Yves Wittwer ◽  
Robert Eichler ◽  
Dominik Herrmann ◽  
Andreas Türler
Keyword(s):  
Metal Carbonyl ◽  
Ambient Air ◽  
Single Atom ◽  
Carbonyl Complex ◽  
Carbonyl Complexes ◽  
On Line ◽  
Carrier Gases ◽  
And Performance ◽  
Atom Chemistry

Abstract A new setup named Fast On-line Reaction Apparatus (FORA) is presented which allows for the efficient investigation and optimization of metal carbonyl complex (MCC) formation reactions under various reaction conditions. The setup contains a 252Cf-source producing short-lived Mo, Tc, Ru and Rh isotopes at a rate of a few atoms per second by its 3% spontaneous fission decay branch. Those atoms are transformed within FORA in-situ into volatile metal carbonyl complexes (MCCs) by using CO-containing carrier gases. Here, the design, operation and performance of FORA is discussed, revealing it as a suitable setup for performing single-atom chemistry studies. The influence of various gas-additives, such as CO2, CH4, H2, Ar, O2, H2O and ambient air, on the formation and transport of MCCs was investigated. O2, H2O and air were found to harm the formation and transport of MCCs in FORA, with H2O being the most severe. An exception is Tc, for which about 130 ppmv of H2O caused an increased production and transport of volatile compounds. The other gas-additives were not influencing the formation and transport efficiency of MCCs. Using an older setup called Miss Piggy based on a similar working principle as FORA, it was additionally investigated if gas-additives are mostly affecting the formation or only the transport stability of MCCs. It was found that mostly formation is impacted, as MCCs appear to be much less sensitive to reacting with gas-additives in comparison to the bare Mo, Tc, Ru and Rh atoms.

scholarly journals The influence of physical parameters on the in-situ metal carbonyl complex formation studied with the Fast On-line Reaction Apparatus (FORA)

2021 ◽  
Vol 109 (4) ◽  
pp. 261-281
Author(s):  
Yves Wittwer ◽  
Robert Eichler ◽  
Dominik Herrmann ◽  
Andreas Türler
Keyword(s):  
Gas Flow ◽  
Metal Carbonyl ◽  
Fission Products ◽  
Reaction Chamber ◽  
Single Atom ◽  
Physical Parameters ◽  
Carbonyl Complex ◽  
Reaction Conditions ◽  
On Line ◽  
The Impact

Abstract The Fast On-line Reaction Apparatus (FORA) was used to investigate the influence of various reaction parameters onto the formation and transport of metal carbonyl complexes (MCCs) under single-atom chemistry conditions. FORA is based on a 252Cf-source producing short-lived Mo, Tc, Ru and Rh isotopes. Those are recoiling from the spontaneous fission source into a reaction chamber flushed with a gas-mixture containing CO. Upon contact with CO, fission products form volatile MCCs which are further transported by the gas stream to the detection setup, consisting of a charcoal trap mounted in front of a HPGe γ-detector. Depending on the reaction conditions, MCCs are formed and transported with different efficiencies. Using this setup, the impact of varying physical parameters like gas flow, gas pressure, kinetic energy of fission products upon entering the reaction chamber and temperature of the reaction chamber on the formation and transport yields of MCCs was investigated. Using a setup similar to FORA called Miss Piggy, various gas mixtures of CO with a selection of noble gases, as well as N2 and H2, were investigated with respect to their effect onto MCC formation and transport. Based on this measurements, optimized reaction conditions to maximize the synthesis and transport of MCCs are suggested. Explanations for the observed results supported by simulations are suggested as well.

scholarly journals The influence of gas purification and addition of macro amounts of metal-carbonyl complexes on the formation of single-atom metal-carbonyl-complexes

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Yves Wittwer ◽  
Robert Eichler ◽  
Ronald Zingg ◽  
Dominik Herrmann ◽  
Andreas Türler
Keyword(s):  
Metal Carbonyl ◽  
Fission Products ◽  
Single Atom ◽  
Gas Purification ◽  
Carbonyl Complexes ◽  
Carrier Gas ◽  
Metal Carbonyl Complexes ◽  
Process Gas ◽  
Atom Chemistry ◽  
Co Gas

Abstract Using the Fast On-line Reaction Apparatus (FORA), the influence of various gas-purification columns onto the formation of metal carbonyl complexes (MCCs) under single-atom chemistry conditions was investigated. MCCs were synthesized from single atoms of Mo, Tc, Ru and Rh being produced by the spontaneous fission of 252Cf and recoiling into a CO-gas containing carrier gas atmosphere. The in-situ synthesized MCCs were volatile enough to be transported by the carrier gas to a charcoal trap where they were adsorbed and their subsequent decay was registered by γ-spectrometry. It was found that the type and combination of purification columns used to clean the applied CO-gas strongly influences the obtained formation and transport yields for all MCCs. With the exception of Rh-carbonyl, intense gas-purification strategies resulted in reduced formation and transport yields for MCCs in comparison with less efficient or even completely missing purification setups. It was postulated that the observed reduction in yield might depend on the content of Fe(CO)5 and Ni(CO)4, as well as potentially other MCCs, in the CO-gas, being formed by the interaction between CO and the steel-surfaces of FORA as well as from impurities in the used charcoal traps. Subsequently, it was shown that macro amounts of Fe(CO)5, Ni(CO)4, Mo(CO)6 and Re2(CO)10 added to the used process gas indeed increase significantly the overall yields for MCCs produced by 252Cf fission products. Ni(CO)4 appeared the most potent to increase the yield. Therefore, it was used in more detailed investigations. Using isothermal chromatography, it was shown that Ni(CO)4 does not affect the speciation of carbonyl species produced by the 252Cf fission product 104Mo. For 107Tc, 110Ru and 111Rh a speciation change cannot be excluded. For 111Rh a speciation change cannot be excluded. An inter-carbonyl transfer mechanism is suggested boosting the formation of MCCs. The current discovery might allow for new opportunities in various research fields, which are currently restricted by the low overall yields for MCCs produced under single-atom chemistry conditions. Examples are the chemical investigation of transactinides or the generation of radioactive ion beams from refractory metals at accelerators.

scholarly journals In-situ formation, thermal decomposition, and adsorption studies of transition metal carbonyl complexes with short-lived radioisotopes

2014 ◽  
Vol 102 (12) ◽  
Author(s):  
Julia Even ◽  
Alexander Yakushev ◽  
Christoph Emanuel Düllmann ◽  
Jan Dvorak ◽  
Robert Eichler ◽  
...  
Keyword(s):  
Thermal Decomposition ◽  
Transition Metal ◽  
Metal Carbonyl ◽  
Carbonyl Complexes ◽  
Adsorption Studies ◽  
Metal Carbonyl Complexes ◽  
In Situ Formation

AbstractWe report on the

scholarly journals VIBRATIONAL SCALING FACTORS FOR Rh(I) CARBONYL COMPOUNDS IN HOMOGENEOUS CATALYSIS

2017 ◽  
Vol 38 (1) ◽  
pp. 43 ◽  
Author(s):  
Emilija Kohls ◽  
Matthias Stein
Keyword(s):  
First Principles ◽  
Carbonyl Compounds ◽  
Metal Carbonyl ◽  
Absolute Error ◽  
Carbonyl Complexes ◽  
Training Set ◽  
Scaling Factors ◽  
Metal Carbonyl Complexes ◽  
Structural Assignment

Metal carbonyl complexes are an important family of catalysts in homogeneous industrial processes. Their characteristic vibrational frequencies allow in situ tracking of catalytic progress. Structural assignment of intermedi-ates is often hampered by the lack of appropriate reference compounds. The calculation of carbonyl vibrational fre-quencies from first principles provides an alternative tool to identify such reactive intermediates. Scaling factors for computed vibrational carbonyl stretching frequencies were derived from a training set of 45 Rh-carbonyl complexes using the BP86 and B3LYP functionals. The systematic scaling of the computed C=O frequencies yields accurate calculation and assignment of the experimentally obtained 𝜈(CO) values. The vibrational scaling factors can be used to identify reaction intermediates of the industrially relevant Rh-catalyzed hydroformylation reaction. The absolute error between calculated and experimental spectra was significantly reduced and the experimental spectra were as-signed successfully.

Photoreduction of CO to Methanol. The Photolysis of Aqueous Solutions of [Os(NH3)5(CO)]2+

2013 ◽  
Vol 68 (12) ◽  
pp. 1371-1374
Author(s):  
Horst Kunkely ◽  
Arnd Vogler
Keyword(s):  
Aqueous Solution ◽  
Aqueous Solutions ◽  
Artificial Photosynthesis ◽  
Metal Carbonyl ◽  
Carbonyl Complex ◽  
Carbonyl Complexes ◽  
Metal Carbonyl Complexes

The carbonyl complex [OsII(NH3)5(CO)]2+ undergoes a photolysis in aqueous solution which yields [OsVI(NH3)4N]3+ (Φ=10-3 at λirr =255 nm) and methanol. This photoreduction of CO to CH3OH represents a novel type of photoreactivity of metal carbonyl complexes and could be utilized for an artificial photosynthesis

scholarly journals A versatile, refrigerant- and cryogen-free cryofocusing–thermodesorption unit for preconcentration of traces gases in air

2016 ◽  
Vol 9 (11) ◽  
pp. 5265-5279 ◽  
Author(s):  
Florian Obersteiner ◽  
Harald Bönisch ◽  
Timo Keber ◽  
Simon O'Doherty ◽  
Andreas Engel
Keyword(s):  
Rapid Heating ◽  
Ambient Air ◽  
In Situ Monitoring ◽  
Gas Chromatography Mass Spectrometry ◽  
Research Station ◽  
Vacuum Insulation ◽  
Laboratory Operation ◽  
And Performance ◽  
Set Up

Abstract. We present a compact and versatile cryofocusing–thermodesorption unit, which we developed for quantitative analysis of halogenated trace gases in ambient air. Possible applications include aircraft-based in situ measurements, in situ monitoring and laboratory operation for the analysis of flask samples. Analytes are trapped on adsorptive material cooled by a Stirling cooler to low temperatures (e.g. −80 °C) and subsequently desorbed by rapid heating of the adsorptive material (e.g. +200 °C). The set-up involves neither the exchange of adsorption tubes nor any further condensation or refocusing steps. No moving parts are used that would require vacuum insulation. This allows for a simple and robust design. Reliable operation is ensured by the Stirling cooler, which neither contains a liquid refrigerant nor requires refilling a cryogen. At the same time, it allows for significantly lower adsorption temperatures compared to commonly used Peltier elements. We use gas chromatography – mass spectrometry (GC–MS) for separation and detection of the preconcentrated analytes after splitless injection. A substance boiling point range of approximately −80 to +150 °C and a substance mixing ratio range of less than 1 ppt (pmol mol−1) to more than 500 ppt in preconcentrated sample volumes of 0.1 to 10 L of ambient air is covered, depending on the application and its analytical demands. We present the instrumental design of the preconcentration unit and demonstrate capabilities and performance through the examination of analyte breakthrough during adsorption, repeatability of desorption and analyte residues in blank tests. Examples of application are taken from the analysis of flask samples collected at Mace Head Atmospheric Research Station in Ireland using our laboratory GC–MS instruments and by data obtained during a research flight with our in situ aircraft instrument GhOST-MS (Gas chromatograph for the Observation of Tracers – coupled with a Mass Spectrometer).

scholarly journals Evaluation of NO<sup>+</sup> reagent ion chemistry for on-line measurements of atmospheric volatile organic compounds

2016 ◽  
Author(s):  
Abigail R. Koss ◽  
Carsten Warneke ◽  
Bin Yuan ◽  
Matthew M. Coggon ◽  
Patrick R. Veres ◽  
...  
Keyword(s):  
Volatile Organic Compounds ◽  
Organic Compounds ◽  
Ambient Air ◽  
In Situ Measurement ◽  
High Mass ◽  
Urban Air ◽  
Ion Chemistry ◽  
Volatile Organic ◽  
On Line

Abstract. NO+ chemical ionization mass spectrometry (NO+ CIMS) can achieve fast (sub 1-Hz) on-line measurement of trace atmospheric volatile organic compounds (VOCs) that cannot be ionized with H3O+ ions (e.g. in a PTR-MS or H3O+ CIMS instrument). Here we describe the adaptation of a high-resolution time-of-flight H3O+ CIMS instrument to use NO+ primary ion chemistry. We evaluate the NO+ technique with respect to compound specificity, sensitivity, and VOC species measured compared to H3O+. The evaluation is established by a series of experiments including laboratory investigation using a gas-chromatography (GC) interface, in-situ measurement of urban air using a GC interface, and direct in-situ measurement of urban air. The main findings are that (1) NO+ is useful for isomerically resolved measurements of carbonyl species; (2) NO+ can achieve sensitive detection of small (C4–C8) branched alkanes, but is not unambiguous for most; and (3) compound-specific measurement of some alkanes, especially iso-pentane, methylpentanes, and high mass (C12–C15) n-alkanes, is possible with NO+. We also demonstrate fast in-situ chemically specific measurements of C12 to C15 alkanes in ambient air.

scholarly journals A versatile, refrigerant-free cryofocusing-thermodesorption unit for preconcentration of traces gases in air

2016 ◽  
Author(s):  
F. Obersteiner ◽  
H. Bönisch ◽  
T. Keber ◽  
S. O'Doherty ◽  
A. Engel
Keyword(s):  
Rapid Heating ◽  
Ambient Air ◽  
In Situ Monitoring ◽  
Gas Chromatography Mass Spectrometry ◽  
Research Station ◽  
Stage Design ◽  
Vacuum Insulation ◽  
Laboratory Operation ◽  
And Performance

Abstract. We present a compact and versatile cryofocusing thermodesorption unit, which we developed for quantitative analysis of halogenated trace gases in ambient air. Possible applications include aircraft-based in-situ measurements, in situ monitoring and laboratory operation for the preconcentration of analytes from flask samples. Analytes are trapped on adsorptive material cooled by a Stirling cooler to low temperatures (e.g. −80 °C) and desorbed subsequently by rapid heating of the adsorptive material (e.g. +200 °C). The setup neither involves exchange of adsorption tubes nor any further condensation or refocusation steps. No moving parts are used that would require vacuum insulation. This allows a simple and robust single stage design. Reliable operation is ensured by the Stirling cooler, which does not require refilling of a liquid refrigerant while allowing significantly lower adsorption temperatures compared to commonly used Peltier elements. We use gas chromatography mass spectrometry for separation and detection of the preconcentrated analytes after splitless injection. A substance boiling point range of approximately −80 °C to +150 °C and a substance mixing ratio range of less than 1 ppt (pmol mol−1) to more than 500 ppt in preconcentrated sample volumes of 0.1 to 10 L of ambient air is covered, depending on the application and its analytical demands. We present the instrumental design of the preconcentration unit and demonstrate capabilities and performance through the examination of injection quality, analyte breakthrough and analyte residues in blank tests. Application examples are given by the analysis of flask samples collected at Mace Head Atmospheric Research Station in Ireland using our laboratory GC TOFMS instrument and by data obtained during a research flight with our in-situ aircraft instrument GhOST MS.

Gas phase synthesis of 4d transition metal carbonyl complexes with thermalized fission fragments in single-atom reactions

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Michael Götz ◽  
Stefan Götz ◽  
Jens-Volker Kratz ◽  
Jochen Ballof ◽  
Christoph E. Düllmann ◽  
...  
Keyword(s):  
Complex Formation ◽  
Gas Phase ◽  
Fission Products ◽  
Superheavy Elements ◽  
Transport Processes ◽  
Single Atom ◽  
Carbonyl Complex ◽  
Carbonyl Complexes ◽  
Phase Synthesis ◽  
Gas Phase Synthesis

Abstract The formation of carbonyl complexes using atom-at-a-time quantities of short-lived transition metals from fusion and fission reactions was reported in 2012. Numerous studies focussing on this chemical system, which is also applicable for the superheavy elements followed. We report on a novel two-chamber approach for the synthesis of such complexes that allows spatial decoupling of thermalization and gas-phase carbonyl complex synthesis. Neutron induced fission on 235U and spontaneous fission of 248Cm were employed for the production of the fission products. These were stopped inside a gas volume behind the target and flushed with an inert-gas flow into a second chamber. This was flushed with carbon monoxide to allow the gas-phase synthesis of carbonyl complexes. Parameter studies of the transfer from the first into the second chamber as well as on the carbonyl complex formation and transport processes have been performed. High overall efficiencies of more than 50% were reached rendering this approach interesting for studies of superheavy elements. Our results show that carbonyl complex formation of thermalized fission products is a single-atom reaction, and not a hot-atom reaction.

Remote On-Line Control of a High-Voltage in situ Transmission Electron Microscope with A Rational User Interface

1996 ◽  
Vol 54 ◽  
pp. 384-385
Author(s):  
M.A. O’Keefe ◽  
J. Taylor ◽  
D. Owen ◽  
B. Crowley ◽  
K.H. Westmacott ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Electron Microscope ◽  
User Interface ◽  
Transmission Electron Microscope ◽  
High Voltage ◽  
Materials Science ◽  
Transmission Electron ◽  
On Line ◽  
Electron Microscopes

Remote on-line electron microscopy is rapidly becoming more available as improvements continue to be developed in the software and hardware of interfaces and networks. Scanning electron microscopes have been driven remotely across both wide and local area networks. Initial implementations with transmission electron microscopes have targeted unique facilities like an advanced analytical electron microscope, a biological 3-D IVEM and a HVEM capable of in situ materials science applications. As implementations of on-line transmission electron microscopy become more widespread, it is essential that suitable standards be developed and followed. Two such standards have been proposed for a high-level protocol language for on-line access, and we have proposed a rational graphical user interface. The user interface we present here is based on experience gained with a full-function materials science application providing users of the National Center for Electron Microscopy with remote on-line access to a 1.5MeV Kratos EM-1500 in situ high-voltage transmission electron microscope via existing wide area networks. We have developed and implemented, and are continuing to refine, a set of tools, protocols, and interfaces to run the Kratos EM-1500 on-line for collaborative research. Computer tools for capturing and manipulating real-time video signals are integrated into a standardized user interface that may be used for remote access to any transmission electron microscope equipped with a suitable control computer.

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