Mathias Strauss

Questions and Answers (119) View all

• Answer added in Nanomaterials Synthesis
  6 How can a material show photoactivity in visible region by having bandgap of 3.6 e.V. ?
  By Naveen Veldurthi · Osmania University
  Mathias Strauss · Universidade Estadual de Campinas

  Have you performed a reaction without the photocatalyst? Do you observe degradation of your substrate? How are you filtering your light source? Some ... [more]

  Have you performed a reaction without the photocatalyst? Do you observe degradation of your substrate? How are you filtering your light source? Some photocatalytic reaction occur under IR illumination. Therefore its better to use a additional water filter to remove the IR radiation. What is your catalyst? What is the substrate you wanna degradate?
  Following
• Answer added in XRD Analysis
  8 Please tell me how to calculate Crystal Size using XRD Data?
  By Asim Umer · University of Engineering and Technology, Lahore
  Mathias Strauss · Universidade Estadual de Campinas

  You can't just use the Scherrer equation for the crystallite size calculation with these data. You have to substact the instrumental line broadening u... [more]

  You can't just use the Scherrer equation for the crystallite size calculation with these data. You have to substact the instrumental line broadening using a diffractogram from a well crystalline sample of Si or BaF2 for example. Another point is that Scherrer not always gives you a real crystallite size value, this because the FWHM is affected not only by the particle size as by the structural strain. It must be pointed out also that the shape constant (k = 0.89 ~0.9) is used for spherical particles, so that you need to be sure that your crystallits are spherical.
  Following
• Answer added in Magnetic Nanoparticles
  2 Biolistic transformation of bacteria with magnetic nanoparticles.
  By Bharat Behl · United Arab Emirates University
  Mathias Strauss · Universidade Estadual de Campinas

  I had never worked with such biological systems and it is quite far from my work area. One suggestion I have is that if you are sure that your magneti... [more]

  I had never worked with such biological systems and it is quite far from my work area. One suggestion I have is that if you are sure that your magnetic NP are between 200-250 nm big why not try a filtration? You can separe the NP from the bacteria that way...
  Following
• Answer added in Nanoparticles
  8 Is there any way to know the formation of core-shell nanoparticle using UV-visible or PL?
  By Sunil Sahi · University of Texas at Arlington
  Mathias Strauss · Universidade Estadual de Campinas

  Recently we have published a work that describes how the Eu3+ emission spectra can be used to probe SnO2 particle size. In this case we used the diffe... [more]

  Recently we have published a work that describes how the Eu3+ emission spectra can be used to probe SnO2 particle size. In this case we used the difference in the emission of the Eu ions located in the surface and in the bulk of the SnO2 NPs. Crystalline SnO2 Nanoparticles Size Probed by Eu3+ Luminescence Mathias Strauss, Thalita A. Destefani, Fernando A. Sigoli, and Italo O. Mazali Crystal Growth & Design, 2011, 11 (10), pp 4511–4516 Publication Date (Web): August 29, 2011 (Article) DOI: 10.1021/cg2007292 Probably the same approach can be used to define if you are getting a core@shell system or not. But it depends on the dopant and host characteristic. Reading this article maybe will help you in opening your mind for new ideas and on giving you some insights. Another issue that you may use at the PL analysis is the emission life time of your rare earth that may be different if you have a core@shell system. But I suggest looking into the literature for getting additional information in this case.
  Following
• Answer added in Nanoparticles
  8 Is there any way to know the formation of core-shell nanoparticle using UV-visible or PL?
  By Sunil Sahi · University of Texas at Arlington
  Mathias Strauss · Universidade Estadual de Campinas

  What is the composition of your system? If you have a noble metal@oxide (core@shell) system where the noble metal exhibits surface plasmon ressonance... [more]

  What is the composition of your system? If you have a noble metal@oxide (core@shell) system where the noble metal exhibits surface plasmon ressonance UV-vis absorption band (Au, Ag or Cu) is it possible by UV-vis to know the formation of a core@shell NP. Please give us more details of yous system so that we can give tips about it.
  Following