Scanning Probe Microscopy Techniques

AFM can be used to analyze almost any sample, unlike STM that needs some conductivity.

AFM can operate in various environments, including liquids, without needing a vacuum.

AFM doesn't damage the sample, allowing further analysis after imaging.

AFM allows for easy adjustment of the tip-sample interaction, providing flexibility in analysis.

AFM is generally affordable due to its versatile and accessible design.

A technique that uses a probe to scan a surface and measure a specific interaction, providing a pixel value for each point.

A type of scanning probe microscopy that measures the electric current flowing between a sharp tip and the sample surface.

The highest occupied energy level in a metal, similar to the HOMO in molecules.

The energy needed to remove an electron from the metal and bring it to rest outside the metal.

A microscopic technique that analyzes the forces between a sharp tip and a sample surface, producing a 3D image.

The ability to distinguish between two closely spaced objects, usually determined by the instrument's resolution.

A device that enables precise movement in a specific direction, often used to control the position of the tip or sample in scanning probe microscopy.

The process where electrons can pass through a potential barrier even if they don't have enough energy to do so classically. This happens in the atomic scale in a STM.

The energy required to remove an electron from an atom or molecule.

A sharp metal tip used in Scanning Tunneling Microscopy (STM) to create a tiny gap between tip and sample.

The process by which electrons can pass through a potential barrier, even if they don't have enough energy classically.

The current that flows between the STM tip and the sample due to electron tunneling.

The distance between the STM tip and the sample.

A feedback loop used in STM to maintain a constant tunneling current by adjusting the tip height.

The ability of the STM to measure the height of the surface with atomic precision.

The highest occupied molecular orbital in a molecule.

The lowest unoccupied molecular orbital in a molecule.

The process of applying a voltage bias between the STM tip and the sample to control the energy of electrons tunneling.

A small, flexible beam with a sharp tip at the end used in AFM to measure forces between the tip and the sample.

The deflection of the cantilever in AFM, measured by reflecting a laser beam off its back.

The ability to control the position of the STM tip with great precision in three dimensions.

A technique used in SPM to create a map of the surface by measuring the interaction between the tip and the sample at different positions.

The force that causes a cantilever to bend, measured using Hooke's Law: F = -kx, where k is the cantilever spring constant and x is the vertical displacement.

The ability of an AFM to detect attractive or repulsive forces between the tip and the surface, leading to variations in laser beam deflection and measured voltage.

The phenomenon where the radius of the AFM tip influences the final image due to overlapping interactions with surface features.

The width of a feature as recorded by the AFM, influenced by the tip's radius and the actual feature size.

An AFM operating mode where the tip is constantly pushed into the surface, maintaining a constant cantilever deflection.

An AFM mode where the cantilever is oscillated at its resonant frequency, causing the tip to tap the surface intermittently, and the amplitude of oscillation is kept constant.

The shift in driving frequency required to maintain a constant amplitude oscillation in tapping mode, caused by the interaction between the tip and the surface.

An AFM mode where the tip is oscillated just above the surface, maintaining a constant amplitude of oscillation, highly sensitive to attractive forces.

A specialized AFM technique where functional groups are attached to the tip for probing the chemical composition of a surface.

The ability to measure the adhesive interaction between specific functional groups attached to the AFM tip and the surface.

A modified AFM technique that relies on the specific interactions of functional groups on the tip to reveal the chemical composition of a surface.

The ease of use and versatility in studying various materials.

Limitations of AFM, such as the possibility of damaging soft samples and the challenge of imaging very small features.