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Mossbauer Molecular Spectroscopy

#0736


Analytical Gamma-Resonance (Mossbauer) Molecular Spectroscopy

Tech Area / Field

  • ENV-MIN/Monitoring and Instrumentation/Environment

Status
3 Approved without Funding

Registration date
02.09.1996

Leading Institute
NPO Chimavtomatica, Russia, Moscow

Supporting institutes

  • Russian Academy of Sciences / Semenov Institute of Chemical Physics, Russia, Moscow

Collaborators

  • Rijksuniversiteit Groningen, The Netherlands, Groningen\nTechnische Universität München, Germany, Munich\nUniversita Degli Studi di Parma / Departamento di Fisica, Italy, Parma\nUniversität zu Lübeck / Institute für Physik, Germany, Lübeck\nOpen University, UK, Walton Hall

Project summary

The main goal of the Project is to create a new analytical method for the environment control and monitoring of environment for supertoxicants present in gas and liquid phases.

The analytical gamma-resonance (Mossbauer) molecular spectroscopy (AGRMS) is determined as a technique for the study of the molecular composition and compound states which is based on an information being contained in the gamma-resonance spectra of the Mossbauer atoms, which have been artificially introduced into the analytical reagents. The Mossbauer spectrum records nuclear gamma-transitions taking place without the change of nucleus recoil energy and connected with electron shells via hyperfine interactions of the nucleus and outer valence electrons of the Mossbauer atom.

Thus, the AGRMS is characterized by a generalized analytical parameter which is the ratio of Mossbauer absorption line width (~10-8 eV) to the energy of nucleus transition (~104 eV). For AGRMS, the value of this parameter is a record one and exceeds that in the optical spectroscopy (conventional method in analytical chemistry) by a quantity of 6-7 orders.

The AGRMS is realized in the form of sorption Mossbauer sensors (MS) permitting selective analytical reactions in the pore of sorbents where collective transformations of the Mossbauer atoms result from chemical reaction of reagent for the determined supertoxicant. This effect, called by us as "chemical amplification", increases the sensitivity of analysis by a factor of 100-1000 because a single analyzed molecule causes transformation of the whole aggregates and clusters of the Mossbauer atoms. Thus, the AGRMS ensures the value of sensitivity up to 10-10 mg/m3 preserving high level of selectivity at the same time. For AGRMS, this provides large advantages compared to such traditional techniques as IR and optic spectroscopy, chromatography, etc. Besides high sensitivity, the AGRMS possesses of one more advantage compared to such highly sensitivity method as chromate-mass-spectrometry. Indeed, for the AGRMS, one does not need to concentrate the probe before the measurements that simplifies and anticipates an analysis.

The priority in the creation of the AGRMS, analytical reactions and experimental samples of MS belongs to Russian scientists involved in programs on defense chemistry.

Some model developments were transmitted into the independent organization for the pilot tests with participation of the Defense Ministry Institutions. The practical approval of the method was performed by the powerful toxicants including real gases like V-gases.

The results of selective determinations of such substances by the background of interfering components (conflagration smokes, automobile exhausts, natural background, etc.) were officially recorded by the concentration level of 10-10 mg/m3. However, in spite of these unique results, the further works were canceled because of the absence of the state financial support.

The goal of the Project is in accordance with the main goals of ISTC, i.e. to support the fundamental and applied works and technical developments in the pacific aims, including protection and monitoring of environment and destruction of chemical weapons as well.

The technical approach of the AGRMS includes the development and application of the following basic components of the research work:


- sorption MS for gas and liquid medium;
- metrological supply in the form of standard samples for determined supertoxicants and in the form of methods of preparation of calibrated mixtures obtained from the standard samples;
- devices ensuring quantitative influence of controlling medium on MS;
- devices for fixing and processing analytical gamma-resonance (Mossbauer) spectra;
- devices for fixing and processing analytical characteristic of MS;
- complexes of gamma-resonance devices with computers for obtaining, processing and keeping GR spectra.

The Project is suggested to realize for 3 years. The following works are supposed to be done:


- selection and testing of selective analytical reaction for supertoxicants and chemical complexes including Mossbauer atoms (Fe, Sn, Eu);
- synthesis of the Mossbauer sensors applicable to determine the priority supertoxicants;
- elaboration of metrological and methodological support for the study of analytical parameters of the MS: sensitivity threshold, selectivity, and basic errors;
- assembly and adjustment of gamma-resonance (Mossbauer) spectrometers (GRS) and spectrometers of Rayleigh scattering of Mossbauer radiation (RSMR) equipped with the temperature maintaining system for the study of MS, spectrometer-computer communication units and elaborated software for the treatment of GR.- and RSMR-spectra;
- preparation of test equipment ensuring quantitative action of standard medium and security of personnel;
- study of metrological characteristics of MS according to the requirements of the State Committee of Standards (Russian Federation) by air, water and nutrition control.

The scientific significance of the AGRMS is based on the application of the first elaborated and original approaches including the following: 1) creation of the sorption Mossbauer sensors (MS), 2) use of selective analytical reactions in gas and liquid phases with participation of the Mossbauer atoms or groups of atoms (clusters), 3) realization of the effects of acceleration of the selective chemical reactions in pores of sorbents, 4) application of the effect of "chemical amplification", i.e. collective transformations of the Mossbauer atoms during the reactions of MS with supertoxicants yielding aggregates and nanoclusters, 5) utilization of unusual physical and chemical properties of nanoclusters in MS for identification and analysis of supertoxicants.

The commercial significance of the AGRMS consists in creation of the net of the Mossbauer sensors fabricated in the form of disks with sizes of 2.0 - 2.5 cm and served for monitoring of an environment An analysis in several analytic centers is considered to be done next. On account of this approach the AGRMS permits to unify analysis and make it less expensive.

Collaborators of the Project take part in elaboration of special apparatus for Mossbauer studies, in elaboration of the Mossbauer sensors, in ecological and medical studies, in simulation of chemical and aggregate transformations. The development of new Mossbauer analytical approaches permitting to solve ecological and environment tasks will be carried out with the participation of Professor, Dr. F. Berry (Department of Chemistry, The Open University, England). Ecological, biophysical and medical studies are supposed to be carried out in collaboration with Professor Dr. G. Albanese (Dipartimento di Fisica Universita'di Parma, Italy). An elaboration of new nanocluster systems for Mossbauer sensors and the study of physical and chemical properties of nanoclusters used for determination and utilization of amino derivatives, metal carbonyls and sulfur compounds (H2S, alcohol's, sulfur feed stock) will be carried out with the participation of Professor Dr. A. X. Trautwein (Institute fur Physik Medizinische Universitat, Lubeck, Germany).


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