Beams of Liquid and Solid Nanocluster Ions
Converting of Ion Beams of Accelerators into Beams of Accelerated Metal Nanoclusters – 2-60 nm in Liquid and Solid State, Detection and Application in Molecular Biology Thereof
Tech Area / Field
- PHY-ANU/Atomic and Nuclear Physics/Physics
- INS-DET/Detection Devices/Instrumentation
8 Project completed
Senior Project Manager
Bunyatov K S
Khlopin Radium Institute, Russia, St Petersburg
- University of Padua / Dipartimento di Fisica "G.Galilei", Italy, Padova\nUniversitat Kaiserslautern, Germany, Kaiserlautern\nCNRS / Institut de Physique Nucléaire - Orsay, France, Orsay\nTechnische Universität Darmstadt / Institut für Kernphysik, Germany, Darmstadt\nIstituto Nazionale di Fisica Nucleare (INFN) / Laboratori Nazionali di Legnaro, Italy, Padova\nUniversity of Uppsala / Division of Ion Physics, Sweden, Uppsala\nMalardalens University, Sweden, Eskilstuna
Project summary1. Project goals:
1.1. Development of a universal installation for conversion of beams of atomic and polyatomic ions of accelerators into intensive (up to ~109 c-1 and more) beams of accelerated nanoclusters in the liquid and solid state within a wide size range of 2-60 nm (2×102-7×106 atoms in cluster with the mass up to 1×109 amu) and larger, with narrow size distributions (FWHM: 10-15% for clusters <20 nm and 20-30% for 25-60 nm clusters), on the basis of a new desorption method.
1.2. Solution of the problem of detection of very heavy – up to 1×109 amu and slow < 5×102 m/s nanocluster ions.
1.3. For a wider use of the method and the installation and development of desorption models studies of desorption of nanoclusters out of metal targets are going to be conducted within the wide dispersity range (2-100 nm) with atomic and polyatomic ions of accelerators in the electronic, nuclear and mixed stopping modes, within a wide range of energy losses: (dE/dx)e= 0.5-80 keV/nm, (dE/dx)n= 10-100 keV/nm.
1.4. The first application of beams of accelerated nanocluster ions with the declared parameters in molecular biology: (1.4.1) for the desorption of biomolecules as a new alternative method with respect to PDMS, MALDI [1. M.Karas and F.Hillenkamp, Anal.Chem. 60 (1988) 2299], ESI [2. J. Fenn, M.Mendall et al., Science 246 (1989) 64]; (1.4.2) obtaining of nanostructured surfaces with the increased adhesion of metal nanoclusters to the surface for adsorption thereon of biomolecules from solutions for purposes of further investigations of properties of biomolecules.
Importance of the development of new ways of production and characterizing of nanoclusters of the matter in different aggregate states is explained by the fact that their physical properties differ substantially from those of bulk matter and are regulated by their size [3. Clusters of Atoms and Molecules, ed. H.Haberland, Springer Verlag, 1994; 4. A.W.Castleman, Jr. et al. J. Phys. Chem. 100 (1996) 12911]. The width of the transition zone (between the behaviour of the matter in the atomic and solid state) is determined by the process under study and may be from tens-hundreds of atoms/cluster (5-100 nm), for example for formation of electron structure of metals, up to 104-107 atoms/cluster (5-100 nm), where spatial confinement of different collective processes including transfer processes, is important. This fact as well as new properties which occur in “cluster-surface” systems with their interaction determines application of nanoclusters: in chemical catalysis [5. A. Sanchez et al. J. Phys. Chem. A 103 (1999) 9573], optoelectronics, nanoelectronics, magnetic instruments, high-strength materials, covers etc. [6. H.J.Fecht, Europhys. News 28 (1997) 89].
2. The state of the things in the fields of problems under solution.
2.1.At present the most highly developed sources of nanoclusters are those of condensation type [7. B. Pauwels et al. Phys. Rev. B 62 (2000) 10383, 8. H. Haberland et al. Phys. Rev. B 51 (1995) 11061]. The most advanced source of this type (University of Freiburg and Oxford Applied Research) allows for obtaining cluster ions of different matters within the size range up to 20 nm with the size resolution (FWHM) – ~20% [9. ww.oaresearch.co.uk/clusters.htm, 2000]. Creation of sources of liquid metal nanocluster ions involves specific difficulties. Obtaining of beams of gold clusters up to ~ 2 nm Au400 (Ekin=10 MeV) on the tandem accelerator of the Institute of Nuclear Physics in Orsay, France is a certain success in this field [10. S. Bouneau et al., Book of Abstracts “Desorption 2000”, P-53]. This means that sources of liquid nanocluster ions with narrow distributions within a wide size range (tens of nm) do not practically exist. This situation puts aside studies and application of liquid (hot!) nanocluster droplets.
2.2. Detection of heavy (up to 1×109 amu) and slow (hundreds of m/s) cluster ions is a problem which hinders the development of new methods of producing particles of larger sizes and their application. High voltage ion-to-ion CsI converters allow for registration of gold cluster ions with the mass up to ~107 amu and m/q up to ~106 by secondary ion emission with the acceleration of 40 kV with the efficiency close to one [12. Van-Tan Nguyen, K. Wien, I. Baranov et al., Rapid Commun. Mass Spectrom. 10 (1996) 1463; 13. I. Baranov et al. SIMS XII, Proc. of the Сonference, Elsevier, 2000, p.303]. Detection of ions with mass > 107 has not been performed before; it is also necessary to test other metals as converters.
2.3. The phenomenon of desorption of metal and semiconductor nanoclusters out of nanodispersed targets by single multiply charged ions (MCI) due to electronic processes [14. I.A.Baranov, et al, Nucl. Instr. and Meth. B 65(1992) 177], discovered and studied by the authors is the physical basis of the new method of obtaining beams of nanocluster ions. The authors show that desorption of nanoclusters is a universal phenomenon, for example, for metals - Au, Ag, Pt, Pd, In, semimetal Bi, semiconductors Ge, PbS, UO2 [15. ISTC Project №902-98; 16. I. Baranov et al., “Desorption 2000” Book of Abstracts O-09]. Yields of desorbed clusters depend on a number of parameters, reach high values - ~0.1-5 cl./ion [15; 17. I. Baranov et al. Nucl. Instr. and Meth. B 183 (2001) 232], and have high values of charged components (20-90%) . This allows for efficient conversion of MCI accelerator beams into cluster ion beams. In the desorption MCI melt a metal nanoparticle into a liquid droplet . At present so far there is no satisfactory model of the nanocluster desorption process due to electronic processes [15; 18.I.Baranov et al., Nucl.Instr and Meth B35 (1988) 140]. Together with the collaborators from Orsay, France (group of Dr. Le Beyec) it was shown that Au5 with Екин = 6 MeV with relatively low values of ((dE/dx)e= 11 keV/nm and very high values of (dE/dx)n – 50 keV/nm desorb gold nanoclusters with record sizes of 60-80 nm in the liquid and solid state respectively . The necessity appears to figure out the role of the nuclear stopping in nanocluster desorption, which has been neglected before. There are no dependencies of yields of nanoclusters with different sizes from different matters on (dE/dx)e, although they are necessary for correct setting of experiments, finding out the maximum and minimum sizes of desorbed clusters and selection of the most efficient accelerators.
2.4.1. Because of the absence of beams of accelerated nanoclusters with narrow distributions within a wide size range, their application in medicine and biology has not been developed. Dr. Y. Le Beyec и Prof. P. Håkansson and coworkers showed that the higher projectile mass and the energy density deposited into the surface layers of biotargets, the larger biomolecules with higher yields are possible to desorb [19. Int. J. Mass Spectr. Ion Proc. 174 (1998) 101, 20. Int. J. Mass Spectr. Ion Proc. 164 (1997) 193]. However, the sizes of projectiles were not large - <100 atoms. A possibility of desorption of large molecules by a cluster impact is supported by the results of calculations by means of the molecular dynamics method in [ 21. M.Kerford, R.P.Webb, NIM B 180 (2001) 44]. The desorption of intact peptide molecules with the mass of 1346.7 amu was disclosed in first experiments on the desorption of biomolecules by accelerated gold nanoclusters with the mean size of 7 nm from a nanocluster ion source . Heavy metal nanoclusters within the declared range of parameters will open absolutely new capacities in this important and extremely vital direction – analysis of heavy biomolecules.
2.4.2. Change of adhesion of a cluster to the surface and nanocluster morphology at the level of inpidual events of interaction acquires great importance in the present time, since these processes underlie the unique properties of new coating and materials [22. B. Yoon et al. Surf. Sci. 443 (1999) 76]. Therefore, this makes in possible to create nanostructured substrates for the analysis of chemical and biomolecular preparations by Raman spectroscopy methods [23. K.C. Grabar, K.R. Brown et al. Anal.Chem. 69 (1997) 471], probe microscopy [24. A.P. Quist et. al. (1995) Scanning Microscopy 9, 395] etc. Though, here there is a problem of stability of the cluster layer, determined by the adhesion of clusters to the surface, to various effects, in particular, in their immersion into liquid, when both clusters and biomolecules fixed thereto can be washed out. First positive results have been obtained on immobilization of accelerated nanoclusters on the surface .
3. Content of the works and results.
3.1. A new installation is going to be created on the basis of the desorption nanocluster ion source with the isotope (252Cf) MCI source, which has been approved for production of beams of gold nanoclusters (the size range is 2-20 nm, FWHM ~50%; intensity of the nanocluster ion beam ~3×104 s-1) . Parameters of the new installation will differ substantially and have new qualities with respect to the prototype and differ in the cardinal way from sources working on other principles. This is connected 1) with specific features of desorption as a physical process (desorption of melted nanodroplets), 2) use of beams of accelerators and 3) development of new methods of preparation of nanodispersed targets, for example, from colloid metal particles with narrow size distributions – 5-30% - and diameter of up to ~60 nm in the solution [25. ICN Biochemicals, 2000]. The authors have already showed that gold clusters with the mean size of 15 nm, desorbed from a target prepared from gold colloidal particles had the FWHM of ~ 13%, and with 30 nm – 23% , which is a good result for big nanoclusters.
Intensity of a nanocluster ion beam is up to 109 с-1, acceleration – up to 50 kV×q, q = 1-20 e and more (the full energy will be up to 1-2 MeV subject to the cluster size and matter). The installation is going to be consisted of the desorption-collector module for nanocluster beam generation, bombardment of different surfaces by them, determining masses by means of the collector method; the module of the tandem time-of-flight mass-spectrometer with a high voltage ion-ion converter for measuring m/q spectra. Thus, the assemblage of the two modules makes it possible to measure all the vital parameters of the desorbed nanoclusters: masses (sizes), the mean charge, the impact energy on the surface. The upper size limit of nanoclusters (60 nm) is going to be three times as big as that for the best of the available analogues . The primary aggregate state of clusters is liquid. The nanoclusters get solid when passing a small additional flight base. This is an exceptional specific feature of the method applied, which will open a possibility to study and apply liquid – hot - nanoclusters, which is supposed to open new prospects for biology and medicine. The installation may be used both for fundamental and applied investigations and for new developments in the fields of 1) interaction of different ions of accelerators with nanoclusters from different matters and sizes on the surface; 2) interaction of accelarated liquid and solid nanoclusters themselves with a) surfaces, b) with nanoclusters on the surface, including biomolecules, in particular, for analysis of biomolecules; 3) for creation and various use of nanostructured surfaces, including biology; 4) for development and improvement of new properties of thin coating of surfaces using liquid and solid nanoclusters with different parameters; 5) it is also possible to provide soft landing of liquid (hot) metal nanoclusters on the surfaces of maters with lower melting temperatures, which in combination with acceleration may find applications in medicine and biology; 6) it is possible to work with precious, rare, radioactive matters with minimum losses, which is an advantage of the desorption method; 7) to study crystallization of nanoclusters within the wide size range in transition from the liquid to the solid phase in the free state, which is impossible to perform in principle in any other way, 8) simulate matter transfer in space; the installation may also find a number of other applications [5, 6].
3.2. Converters of heavy nanocluster ions into light one will be studied and recommended, with determining the efficiency of detection of nanocluster ions with the mass of 106-1×109 amu for monitoring beams of these ions. The results will be obtained in collaboration with Prof. K. Wien from the Institute of Nuclear Physics at the Technical University, Darmstadt, Germany.
3.3. Research will be performed of desorption of nanoclusters by swift heavy atomic and polyatomic ions of accelerators from nanodispersed metal targets within the extended size range of nanoislets (2-100 nm) and the extended (dE/dx) range. Irradiation modes are: (a) atomic ions – in mainly electronic stopping mode, (dE/dx)e=5-60 keV/nm, which is going to be provided from 13 keV/nm and less - by Ar ions, 20-25 kev/nm - californium fission fragments (S.-Petersburg), 40-60 kev/nm – gold ions on the Legnaro LNL accelerator, Italy (research made with the group of Dr. V.Rigato); (b) polyatomic ions mainly in the electronic stopping mode, (dE/dx)el= 60 keV/nm, which are going to be provided by C60 cluster ions accelerated on the Orsay accelerator (France), and (c) monoatomic and polyatomic ions mainly in the nuclear stopping mode, (dE/dx)n=10-100 keV/nm, - by Aun ions on the accelerator in Lyon (the research made with the group of Y. Le Beyec). The results obtained will allow for determining the role of nuclear stopping, obtaining the dependence of nanocluster yields on (dE/dx)e, determining the most optimal choice and economical use of accelerator beams, and will be used in the development of simulations of this process.
3.4.1. The tandem time-of-flight mass-spectrometer will be used to study desorption of biomolecules from bioorganic layers at the impact of accelerated gold nanocluster ions (2-30 nm, 103-106 at/cluster, 0.1-50 eV/at, full energy up to 1-2 MeV) and determine the future of the use of heavy metal nanoclusters for the analysis of large biomolecules. It is the development and creation of new methods and instruments for analysis of large biomolecules that essential capital investments are nowadays directed to [26. L.Sidorov. Soros Educational Journ. 6(2000) 41].
3.4.2. Acceleration nanoclusters will be used for creation of the technology of the increase of their adhesion to surface for adsorption thereon of bioorganic molecules from solutions for purposes oft heir further study by biochemistry methods. Application of accelerated 2-30 nm nanoclusters in molecular biology is going to be provided in cooperation with the group of Prof. P. Hakansson from Uppsala University (3.4.1) and group of Prof. S. Oskarsson from Eskilstuna University (3.4.2), Sweden. Theoretical calculations of the change in the morphology of gold nanoclusters due to their energy of impact on the surface (3.4.2) and estimation of the possibility of gold nanocluster desorption by Aun ions in the nuclear stopping mode (3.3) is going to be performed using the molecular dynamic method by Prof. H. Urbassek from Kaiserslautern University, Germany.
Works 3.3 and 3.4 involve knowledge of q and m of nanocluster ions. This requires m/q spectra, lateral sizes (TEM) and heights (SFM) of nanoclusters. Measurements of the latter are going to be made in cooperation with Dr. Torzo from Padova University, Italy, with the development of data processing programmes, and group of Prof. Hakansson, Uppsala. The planned studies are also going to be performed in the transition size range of nanoparticles (from atoms to the solid state) – 10-60 nm (and bigger), where sources of such particles with suitable parameters do not exist.
Performance of the project meets the basic ISTC goals: 1) reorientation of weaponry scientists to researches for peaceful purposes; 2) the created installation may be produced both for other research groups and performance of researches in collaboration; 3) results of detection of heavy slow nanocluster ions are oriented to those who is going to deal with such nanoparticles, 4) studies of desorption of biomolecules by accelerated nanocluster ions within the wide mass range will be the basis for the new method of analysis of the composition of bioorganic compounds, as well as creation of nanostructured substrates with reliable adhesion of nanoclusters to surface, will create new conditions of study of biomolecules.
The project involves 7 groups from 4 European countries – Germany, Italy, France and Sweden. Participants of the project are highly qualifies specialists of different profile. The duration of the project is 3 years.
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