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S. A. Pauline
3.7 Scanning Probe Microscopy (SPM)
Scanning Probe Microscopy is a quantitative measuring instrument to study the physical, chemical and surface properties such as topography and nanotribology at the
nanoscale [61]. It uses a physical probe to scan the surface of the sample and it can
image several interactions simultaneously. Three dimensional (3-D) topographical
images of the sample surface with high atomic-scale resolution as well as chemical
information can be generated by this method as the sample surface is felt and not
just seen with electrons or light waves. This technique includes a group of instruments such as Scanning tunneling microscope (STM), Atomic force microscope
(AFM), Lateral force microscope (LFM), magnetic force microscope (MFM), scanning thermal microscope (SThM), Electrical force microscope (EFM) and Near-field
scanning optical microscope (NSOM). Different characteristics of the sample can be
studied by changing the material, configuration of the probe and by modifying the
detection scheme [62]. STM is the most powerful microscope and is used to study the
surface of nanomaterials and biological samples related to microelectronics. STM
can only scan electrically conductive samples.
AFM is a high-resolution type SPM with resolutions of the order of fractions
of a nanometer. AFM is used to study smoothness, texture, presence and size of
pores over the sample surface. Shape and topography of different nanoceramics can
be investigated with AFM [63] AFM can scan any solid surface such as insulators,
conductors, semiconductors, etc., and does not essentially require the sample surface
to be conductive [19].
3.8 Brunauer-Emmett-Teller (BET) Analysis—Physical Gas
Adsorption
Brunauer-Emmett-Teller analysis is an important analysis technique for measuring
the specific surface area, size of particles and pore size distribution of nanomaterials.
Gas molecules are made to adsorb on the sample surface and the physically adsorbed
gases are removed by reducing the partial pressure. The amount of gas required to
fill the pores is measured with respect to gas pressure and the plot is known as gas
adsorption isotherm. Evaluation of the adsorption and desorption branches of these
isotherms and the hysteresis between them reveal information about the size, volume,
and area of the pores. Specific surface area and pore volume of mesoporous or microporous materials can be particularly determined by measuring physical adsorption
of gases [19]. The surface area measurement helps in predicting the bioavailability
of the loaded materials into the nanopores.
S. A. Pauline
3.7 Scanning Probe Microscopy (SPM)
Scanning Probe Microscopy is a quantitative measuring instrument to study the physical, chemical and surface properties such as topography and nanotribology at the
nanoscale [61]. It uses a physical probe to scan the surface of the sample and it can
image several interactions simultaneously. Three dimensional (3-D) topographical
images of the sample surface with high atomic-scale resolution as well as chemical
information can be generated by this method as the sample surface is felt and not
just seen with electrons or light waves. This technique includes a group of instruments such as Scanning tunneling microscope (STM), Atomic force microscope
(AFM), Lateral force microscope (LFM), magnetic force microscope (MFM), scanning thermal microscope (SThM), Electrical force microscope (EFM) and Near-field
scanning optical microscope (NSOM). Different characteristics of the sample can be
studied by changing the material, configuration of the probe and by modifying the
detection scheme [62]. STM is the most powerful microscope and is used to study the
surface of nanomaterials and biological samples related to microelectronics. STM
can only scan electrically conductive samples.
AFM is a high-resolution type SPM with resolutions of the order of fractions
of a nanometer. AFM is used to study smoothness, texture, presence and size of
pores over the sample surface. Shape and topography of different nanoceramics can
be investigated with AFM [63] AFM can scan any solid surface such as insulators,
conductors, semiconductors, etc., and does not essentially require the sample surface
to be conductive [19].
3.8 Brunauer-Emmett-Teller (BET) Analysis—Physical Gas
Adsorption
Brunauer-Emmett-Teller analysis is an important analysis technique for measuring
the specific surface area, size of particles and pore size distribution of nanomaterials.
Gas molecules are made to adsorb on the sample surface and the physically adsorbed
gases are removed by reducing the partial pressure. The amount of gas required to
fill the pores is measured with respect to gas pressure and the plot is known as gas
adsorption isotherm. Evaluation of the adsorption and desorption branches of these
isotherms and the hysteresis between them reveal information about the size, volume,
and area of the pores. Specific surface area and pore volume of mesoporous or microporous materials can be particularly determined by measuring physical adsorption
of gases [19]. The surface area measurement helps in predicting the bioavailability
of the loaded materials into the nanopores.