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Nanoscience and nanotechnology tweezer

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    Nanoscience and
    nanotechnology

                                                                                 Photo: Nelson Chinalia




       The nanoscience and nanotechnology activity at the Brazilian Synchrotron Light
            Laboratory started more than a decade ago, involving efforts in synchrotron
            radiation-based experiments, physical and chemical syntheses of 2D and 3D
          nanostructures, theoretical modeling, manipulation, microfabrication, scaling
      from the nano-scale to the micro-scale, and advanced use of microscopies based on
      electrons (SEM, TEM, and STEM) and scanning probes (AFM and STM). These
         combined efforts seeks the understanding of the materials unique behavior and
         properties and at the nano-scale, the development of new materials, the precise
      control over these materials production, and most important, the search for useful
                           applications for this new generation of materials and devices.
                                                                                                                    Facility Report




   In order to achieve its goals as a national       Electron microscopy
laboratory and in agreement with the effort of the
                                                        The electron microscopy facility was
Brazilian community in the field of nanoscience
                                                     transferred to the new C2Nano center and began
and nanotechnology LNLS installations operate
                                                     welcoming users at this new location in July
as open and multiuser facilities with strong
                                                     2008. Details of the new building’s advanced
activity on the training of specialized human
                                                     design, its construction, and commissioning
resources. The internal research and technical       are presented elsewhere in this report. Part of
team works on the development of new                 the new developments at the center included
methodologies and dedicated instrumentation,         the installation and commissioning of two new
which are linked to both, the in-house and           transmission electron microscopes, funded
users word-class research.                           mainly by FAPESP (The State of São Paulo
                                                     Research Foundation).
   Among the open facilities related to the
                                                        The new microscopes installed at the C2Nano
nanoscience and nanotechnology program are
                                                     building are:
the x-ray diffraction beam-lines, the electron
                                                        A 200 keV TEM-STEM-FEG (1.9 Å point
microscopy laboratory, the scanning probe
                                                     resolution) coupled to STEM BF-DF, and
microscopy laboratory, and the thin-films and
                                                     HAADF detectors, a TV-rate CCD camera, a
microfabrication laboratory. In addition, a set      4-megapixel CCD camera, a large collection
of installations dedicated to in-house research      angle energy dispersive X-ray spectrometer
for chemical synthesis of nanostructures and         (XEDS), and an electron energy loss spectrometer
molecules manipulation are part of this great        (EELS) capable of energy filtered imaging. This
                                                     instrument will be used mainly in studies of
effort of a small group of technicians, engineers,
                                                     the crystallographic, chemical, and electronic
physicists, and researchers in nanoscience
                                                     properties of functional nanostructured materials.
and nanotechnology at LNLS.
                                                     The system’s installation has been completed
   As a result of this long-term effort with         and its commissioning and debugging are
count-less outstanding results and important         under way.
impact on the Cesar Lattes Nanoscience and
Nanotechnology Center (C2Nano) was open for
users in 2008 with the presence of the Brazilian
President, Luiz Inácio Lula da Silva and the
Minister of Science and Technology, Sérgio
Machado Rezende, among other ministers of
state and personalities. This new center will
host an important part of the actual and future
LNLS efforts in this field.

   The overview of the main activities and
new developments in this area during 2008 is
                                                     Figure 1    Disposable salicylicate sensors obtained by deposition of
presented below.                                                 Ti/Au on acetate


                                                                                                          Activity Report 2008 | 113
Nanoscience and nanotechnology




                                A 200 keV TEM-STEM-MSC (2.5 Å point                 It has been nearly 10 years since the electron
                             resolution) coupled to a TV-rate CCD camera,        microscopy laboratory opened its doors to users
                             a 1-megapixel CCD camera, and an XEDS               from all over Brazil and South-America. Since
                             spectrometer. This instrument will be used mainly   then, it has delivered more than 48,300 hours
                             for the study of crystallographic and chemical      of electron microscopy to 1,140 external users,
                             properties of nanostructured functional and         resulting in 332 indexed journal publications.
                             structural materials, and for the development       In 2008 alone, approximately 5,440 hours of
                             of in situ experiments. Commissioning and           TEM and SEM were delivered to external
                             LNLS personnel training were completed and          users involved in 129 research projects, which
                             the system opened for users in July 2008. In        resulted in 49 indexed journal articles. As a
                             addition to user training, 14 research projects     central part of the nanoscience program at
                             were initiated in 2008.                             LNLS, the electron microscopy laboratory
                                The previously existing microscopes are:         continues to train electron microscopists.
                                A 300 keV TEM-HR (1.7 Å point resolution,        Several programs are in place for theoretical
                             1.2 Å information limit) coupled to a TV-rate       and practical training.
                             CCD camera, a 1-megapixel CCD camera, and              Six specialized graduate level courses are
                             an XEDS spectrometer, which is used for the         offered at nearby universities (UNICAMP and
                             study of crystallographic and chemical aspects      USP), some of which are available via the LNLS
                             of nanostructured materials.                        website at no charge. A 3-week summer course
                                A 30 keV SEM-FEG (1.5 nm resolution)             also gives users located far from LNLS the
                             coupled to an XEDS spectrometer and plasma          opportunity to receive a comprehensive theoretical
                             based anti-contaminator, employed in studies        education and practical training on HRTEM,
                             of the morphological, crystallographic and          sample preparation, and data analysis.
                             chemical aspects of micro- and nanostructured
                                                                                    Figures: images of the installed TEMs and
                             materials.
                                                                                 sample Preparation room are suggested.
                                A 30 keV SEM-LV (3.0 nm resolution) coupled
                             to an XEDS spectrometer, EBSD, and stages for
                                                                                 Scanning probe microscopy
                             in situ experimentation, dedicated mainly to the
                             study of the morphological, crystallographic           After a commissioning step following some
                             and chemical properties of microstructured          technical difficulties, the UHV-STM is now
                             materials and advanced in situ experiments          open for users. Currently, the base pressure
                             involving heating and deformation.                  is pressure is in its mid 5E-12 Torr, thanks

                                The SEMs listed above and the sample             to several additions: a 400l/s ion pump and
                             preparation facilities have already been            a non-evaporable getter pump in the main
                             transferred to the C2Nano Building. The             chamber; and for the load-lock (LL) chamber,
                             300 keV TEM-HR and some sample preparation          Ar plasma treatment is applied to all samples
                             equipment will be moved to this new building in     and tips brought into the main chamber.
                             2009. The new sample preparation laboratories       With a base pressure of 5E-8 Torr or better,
                             provide users with more adequate and complete       the LL chamber also has an Ar bombardment
                             installations for the preparation of SEM and        system, a gas manifold allowing for O2 and
                             TEM samples from a wide variety of hard and         N2 plasmas, and a lamp heating system. The
                             soft materials.                                     main chamber currently has Ge, Hf and Ag


114 | Activity Report 2008
                                                                                                                        Facility Report




e-beam evaporation sources, all of which were         to name just two examples, the development of
developed at LNLS. Current experiments                disposable amperometric biosensors (Figure 1) for
involve the reactive deposition of Hf on Si,          salicylicate-based on screen-printed electrodes; and
and metal surface science.                            the development of micro-meshes for the study
   The scanning probe facility also offers two        of DNA irradiation damage by soft X-ray.
AFM systems (Veeco DI Ns3a, and a NTMDT
Solver Pro) for a variety of experiments,             Molecular manipulation
including MFM, EFM, etc.
                                                         Ensemble biochemical analyses provide
                                                      excellent quantitative and qualitative descriptions,
Microfabrication and thin films
                                                      but fail to describe details of phenomena at
   While resident scientists use this facility        the molecular level. The micromanipulation of
extensively, it is also frequently utilized by        individual cells (Figure 2) and molecules opens
visiting users and for industrial projects such as,   the possibility of performing single molecule




                                                 a                                                    b




                                          ∅ 2.2 µm                                             ∅ 3.5 µm




                                            10 µm                                                 10 µm

Figure 2    Scanning electron microscope images of metal mesh filters with different geometrical
            parameters to control exposed areas on the samples (upper panels). Cells were
            irradiated for 6 min using filters with openings of 2.2 µm (left) or 3.5 µm in diameter
            (right), fixed 5 min later and stained for DNA (blue) and γH2AX (red). The scale bar
            has 10 µm size


                                                                                                             Activity Report 2008 | 115
Nanoscience and nanotechnology




                             force spectroscopy. The kinetics, mechanics,         elasticity as a function of the enzyme activity or
                             and variations in structure, function, and           the environment’s conditions. Single molecule
                             interactions can thus be explored, leading to a      techniques such as Atomic Force Microscopy,
                             more complete understanding of physiological         and Optical and Magnetic tweezers are used to

                             processes.                                           characterize molecules on the nanometric scale,
                                                                                  with force measurements in the piconewton
                                Due to Brownian motion, a molecule
                                                                                  range. Applications of these techniques shed
                             experiences many fluctuations in the environment
                                                                                  light into important biological mechanisms
                             in which it performs its functions. An enzyme
                                                                                  such as transcription and translation, and
                             bound to a polymer, such as DNA, RNA or
                                                                                  also into studies of the elasticity of cellulose
                             a carbohydrate, is subject to collisions with
                                                                                  derivatives.
                             water and other molecules that make the entire
                                                                                     The implementation of magnetic tweezers
                             system move rather rapidly. For a thorough
                                                                                  set-ups (Figure 3) is an ongoing effort that
                             characterization of the interactions between
                                                                                  integrates biology and physics expertise
                             these molecules, it is desirable to restrict these   and opens new research opportunities at the
                             movements. One way of accomplishing this             Nanoscience and Nanotechnology laboratory.
                             is through the application of a unidirectional       This effort is cosupported by CNPq through
                             force that stretches the polymer, and subsequent     the Scanning Probe Microscopy Network and
                             monitoring of the changes in the polymer’s           by ABTLuS.




                             Figure 3     Magnetic tweezer setup for manipulation of biological samples



116 | Activity Report 2008
           Facility Report




Activity Report 2008 | 117

				
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