Ricerc@Sapienza

PESCA platform consists in the combination of AFM (with nm resolution) with an electrochemical set-up. This combination  affords simultaneous acquisition of different

types of images (topological activity of electrified surface and correlation with applied electrical potential) unveiling fundamental interfacial properties at nm range

with redox processes examined at the  site of electron transfer.The availability of in situ and in operando techniques in  PESCA 
 allows the characterization of the polarized surface while surface is imaged with the result of attaining the
mapping of different physical properties.PESCA is a set-up that retrieves high resolution images for quantitative mapping via analysis
of detected AFM signal and correlation with the desired physical parameter.PESCA realizes at the sub-microscopic level what other
tools achieve on macroscopic scale,but with the addition of high sensitivity at the nm level,  lateral resolution and high speed of acquisition.PESCA requires very
small size of probed volume of material (as any AFM) and is adequate to the length scale of nanomaterials. Beside opening a new
level of comprehension of the electrochemical phenomena, PESCA presents the absolute novelty of upgrading and expanding the capabilities of
microscopes for the measurement of the mechanical and electrical forces at the nm level  in a non-invasive and non-destructive way. This is particularly attractive  in
the field of metrology concerning the subfields of nanomechanics and nanoelectrostatics. As far as nanomechanical properties are concerned, PESCA is

 fully suitable to analyze soft samples (low range of elastic moduli).  PESCA works as
contact resonance AFM (CR-AFM), in which the resonance of the cantilever in contact with sample surface is analyzed and measures the local
value of sample indentation modulus.CR-AFM is used to analyze samples with elastic modulus ranging from tens of MPa,
e.g.,cells,soft polymers, to hundreds of GPa, e.g. stiff coatings and crystals.In viscoelastic measurements,
cantilever oscillation modes are analyzed to evaluate resonance frequencies and the corresponding quality factors. In PESCA the cantilever is

 excited with accurate selection of the oscillation frequency to avoid spurious signals exploiting the  photothermal effect provoked by
a  laser impinging on the back of the cantilever pulsed at the desired frequency.This results in astonishing narrow spectral
bands around the selected frequency, with a dramatic improvement not only of the speed of tapping mode morphological reconstruction
but also on the accuracy of nanomechanical images. In PESCA the use of photothermal excitation to perform viscoelastic mapping represents
the state of the art in the field of nanomechanical characterizations. Since PESCA affords the imaging of surfaces under electrical polarization,  the occurrence of

electrochemical redox processes in immobilized systems brings about the change of spin state and of electronic magnetic moment in the system undergoing an electron transfer 
process.For this type of transformations the magnetic characterizations at the nm scale magnetic force microscopy (MFM) is well-established and is combined with PESCA.

in a way that impedes the creation of  electrostatic artifacts hampering the accurate evaluation of the magnetic properties of samples thanks to an action of decoupling.

After decoupling, MFM data can be used to image the true distribution of magnetic domains on sample, and to evaluate the magnetic moment or magnetization of single
nanoparticles on sample surface.In this context the simultaneous use of Kelvin probe force microscopy (KPFM, which is also addable to PESCA), which nullifies the
tip-sample bias at each point of the scan,and MFM, which locally nullifies electrostatic tip-sample interactions, is very
effective. KPFM-MFM represents the state of art in nanomagnetic characterizations  is customarily included in PESCA platform.