• Direct Measurement of the Magnitude of the van der Waals Interaction of Single and Multilayer Graphene 

      Chiou, Yu-Cheng; Olukan, Tuza Adeyemi; Almahri, Mariam Ali; Apostoleris, Harry; Chiu, Cheng Hsiang; Lai, Chia-Yun; Lu, Jin-You; Santos, Sergio; Almansouri, Ibraheem; Chiesa, Matteo (Journal article; Tidsskriftartikkel; Peer reviewed, 2018-09-23)
      Vertical stacking of monolayers via van der Waals (vdW) assembly is an emerging field that opens promising routes toward engineering physical properties of two-dimensional materials. Industrial exploitation of these engineering heterostructures as robust functional materials still requires bounding their measured properties so as to enhance theoretical tractability and assist in experimental designs. ...
    • Discerning the Contribution of Morphology and Chemistry in Wettability Studies 

      Sloyan, Karen; Lai, Chia-Yun; Lu, Jin-You; Alfakes, Boulos; Al Hassan, Saeed; Almansouri, Ibraheem; Dahlem, Marcus S; Chiesa, Matteo (Journal article; Tidsskriftartikkel; Peer reviewed, 2018-07-15)
      The wetting behavior of homogeneous systems is now well understood at the macroscopic scale. However, this understanding offers little predictive power regarding wettability when mesoscopic chemical and morphological heterogeneities come into play. The fundamental interest in the effect of heterogeneity on wettability is derived from its high technological relevance in several industries, including ...
    • The evolution in graphitic surface wettability with first-principles quantum simulations: the counterintuitive role of water 

      Lu, Jin-You; Lai, Chia-Yun; Almansoori, Ibraheem; Chiesa, Matteo (Journal article; Tidsskriftartikkel; Peer reviewed, 2018-08-08)
      The surface wettability of graphite has gained a lot of interest in nanotechnology and fundamental studies alike, but the types of adsorptions that dominate its time resolved surface property variations in ambient environment are still elusive. Prediction of the intrinsic surface wettability of graphite from first-principles simulations offers an opportunity to clarify the overall evolution. In this ...
    • Explaining doping in material research (Hf substitution in ZnO films) by directly quantifying the van der Waals force 

      Lai, Chia-Yun; Santos Hernandez, Sergio; Moser, Toni; Alfakes, Boulos; Lu, Chun-Yu; Olukan, Tuza Adeyemi; Rajput, Nitul; Boström, Tobias; Chiesa, Matteo (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-02-04)
      Non-monotonic behavior has been observed in the optoelectronic properties of ZnO thin films as doped with Hf (HZO). Here we propose that two competing mechanisms are responsible for such behaviour. Specifically, we propose that provided two crystal orientations dominate film growth, only one of them might be responsible for direct Hf substitution. Nonmonotonic behaviour is expected at once by ...
    • Getting adhesion force maps with an amplitude-modulation AFM in tapping mode 

      Chiesa, Matteo; Santos, Sergio; Lai, Chia-Yun; Olukan, Tuza Adeyemi (Research report; Forskningsrapport, 2020-07)
      Here we demonstrate how to get adhesion force maps with an amplitude-modulation AFM in tapping mode. Our method is tapping mode but it is carried out at ultra-small amplitudes in the presence of surface water layers. The tip is made to vibrated under the water layer in what we call Small Amplitude Small Set-point AM AFM. We show how this is done with an example based on the Cypher scanning probe ...
    • Getting Hamaker coefficients with an amplitude-modulation AFM in tapping mode 

      Lai, Chia-Yun; Olukan, Tuza Adeyemi; Santos, Sergio; Chiesa, Matteo (Research report; Forskningsrapport, 2020-07)
      We demonstrate how to get Hamaker coefficients with an amplitude-modulation AFM operated in standard tapping mode. The Hamaker coefficient is a physical parameter that provides chemical information about the surface of samples. It is based or emerges from van der Waals forces. We use a Cypher scanning probe microscope from Asylum Research to demonstrate the method. The method is based on the research ...
    • Hydration dynamics and the future of small-amplitude afm imaging in air 

      Santos Hernandez, Sergio; Olukan, Tuza Adeyemi; Lai, Chia-Yun; Chiesa, Matteo (Journal article; Tidsskriftartikkel; Peer reviewed, 2021-11-23)
      Here, we discuss the effects that the dynamics of the hydration layer and other variables, such as the tip radius, have on the availability of imaging regimes in dynamic AFM—including multifrequency AFM. Since small amplitudes are required for high-resolution imaging, we focus on these cases. It is possible to fully immerse a sharp tip under the hydration layer and image with amplitudes similar to ...
    • Insights into TiO<inf>2</inf>thin film photodegradation from Kelvin Probe AFM maps 

      Olukan, Tuza Adeyemi; Sydorenko, Jekaterina; Katerski, Atanas; Al Mahri, Mariam; Lai, Chia-Yun; Al-Hagri, Abdulrahman; Santos Hernandez, Sergio; Chiesa, Matteo (Journal article; Tidsskriftartikkel; Peer reviewed, 2022-06-29)
      The synthesis of TiO2 thin films by the chemical spray pyrolysis method at different titanium isopropoxide (TTIP) to acetylacetone (AcacH) ratios has been shown to lead to the highest photodegradation at 1 (TTIP):8 (AcacH). These films hold promise in the field of indoor pollution treatment. Carbon incorporation into the surface and into the TiO2 lattice could be responsible for the observed ...
    • Investigating the Ubiquitous Presence of Nanometric Water Films on Surfaces 

      Santos Hernandez, Sergio; Amadei, Carlo Alberto; Lai, Chia-Yun; Olukan, Tuza Adeyemi; Lu, Jin-You; Font, Josep; Barcons, Victor; Verdaguer, Albert; Chiesa, Matteo (Journal article; Tidsskriftartikkel; Peer reviewed, 2021-06-25)
      When we speak of nanometric water films on surfaces we are speaking about a truly ubiquitous phenomenon in nature. All surfaces exposed to ambient conditions are covered by a thin film of water that affects or mediates surface chemistry, general physical-chemical processes on surfaces, and even solid–solid interactions. We have investigated this phenomenon for over a decade by exploiting dynamic ...
    • Machine learning assisted quantification of graphitic surfaces exposure to defined environments 

      Lai, Chia-Yun; Santos, Sergio; Chiesa, Matteo (Journal article; Tidsskriftartikkel; Peer reviewed, 2019-06-17)
      We show that it is possible to submit the data obtained from physical phenomena as complex as the tip-surface interaction in atomic force microscopy to a specific question of interest and obtain the answer irrespective of the complexity or unknown factors underlying the phenomena. We showcase the power of the method by asking “how many hours has this graphite surface been exposed to ambient conditions?” ...
    • Predicting the suitability of lateritic soil type for low cost sustainable housing with image recognition and machine learning techniques 

      Olukan, Tuza Adeyemi; Chiou, Yu-Cheng; Chiu, Cheng-Hsiang; Lai, Chia-Yun; Santos Hernandez, Sergio; Chiesa, Matteo (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-01-10)
      From a sustainability point of view, laterites-compressed earth bricks (LCEB) are a promising substitute for building structures in place of the conventional concrete masonry units. On the other hand, techniques for identifying and classifying laterites soil for compressed earth bricks (CEB) production are still relying on direct human expertise or ‘experts’. Human experts exploit direct visual ...
    • Quantitatively reinterpreting atomic force microscopy via the data science paradigm 

      Lai, Chia-Yun (Doctoral thesis; Doktorgradsavhandling, 2019-11-22)
      From the invention of the atomic force microscope (AFM) in 1986, tremendous efforts have been put into developing this tool. The AFM has long been considered as one of the top choices to probe the nanoscale world with the ability to achieve nanoscale resolution imaging of surfaces under different environments. Advances in instrumentation combined with the exploitation of sophisticated data analysis ...
    • Reconstructing force profiles with an amplitude-modulation AFM in tapping mode 

      Olukan, Tuza Adeyemi; Lai, Chia-Yun; Santos, Sergio; Amadei, Carlo Alberto; Chiesa, Matteo (Research report; Forskningsrapport, 2020-07)
      Here we demonstrate how to reconstruct force profiles with an amplitude-modulation AFM operated in in standard tapping mode. Our example is based on the Cypher scanning probe microscope from Asylum Research. The method is based on Sader and Katan’s algorithm, but we have implemented an experimental set-up that allows for robust reconstruction. We discuss the details here.
    • Relating Photoelectrochemistry and Wettability of Sputtered Cu- and N-Doped TiO&lt;sub&gt;2&lt;/sub&gt; Thin Films via an Integrated Approach 

      Garlisi, Corrado; Lai, Chia-Yun; George, Leslie; Chiesa, Matteo; Palmisano, Giovanni (Journal article; Tidsskriftartikkel; Peer reviewed, 2018-06-06)
      We present here an integrated study of the photoelectrochemical and hydrophilic properties of sputtered TiO<sub>2</sub> thin films, enhanced by means of nitrogen (N) and copper (Cu) doping. We investigated the effect that doping has on both photoelectrochemical efficiency and surface properties by employing a variety of techniques spanning from impedance electrochemical impedance spectroscopy to ...
    • Setting-up an amplitude-modulation (AM) AFM for tapping mode 

      Santos, Sergio; Lai, Chia-Yun; Olukan, Tuza Adeyemi; Amadei, Carlo Alberto; Chiesa, Matteo (Research report; Forskningsrapport, 2020)
      In this chapter, we are demonstrate how to set-up an amplitude-modulation (AM) AFM for tapping mode operation. We use a Cypher scanning probe microscope from Asylum Research. We employ our techniques for tip characterization and discuss the attractive and repulsive regimes.
    • Surface aging investigation by means of an AFM-based methodology and the evolution of conservative nanoscale interactions 

      Chiesa, Matteo; Lai, Chia-Yun (Journal article; Tidsskriftartikkel; Peer reviewed, 2018-07-05)
      The divergence in physical properties of surfaces exposed to airborne contaminants in the atmosphere has been widely investigated in recent years, but agreement regarding the role that airborne hydrocarbons and water contamination have on surface property evolution remains elusive. Here we investigate the evolution of a freshly grown highly oriented pyrolytic graphite (HOPG) surface exposed to a ...