Professor Maria Hepel

THE DEPARTMENT OF AT STATE UNIVERSITY OF NEW YORK, POTSDAM N.Y.

CHEMISTRY

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Raman Imaging and Spectroscopy Lab

Chemical and Biological Applications of Raman Spectroscopy (pdf, 7 MB)

Atomic Force Microscopy Lab

Tip interactions

Lectures to other Departments

Nanotechnology Lab

Quartz Crystal Nanobalance Lab

EQCN Principles

Studies

Electrochemical Quartz Crystal Nanobalance (EQCN) technique utilizes quartz vibrations and piezoelectric effect to measure mass changes as small as a fraction of a monolayer of atoms

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CHEMISTRY Dept.

Professor Maria Hepel

hepelmr@potsdam.edu

Atomic Force Microscopy Laboratory

Department of Chemistry

Stowell Hall

44 Pierrepont Ave.

Potsdam , NY 13676, U.S.A.

Tel.: +1.315.267.2267

Fax: +1.315.267.3170

AFM Fundamentals

AFM tip interaction with sample

(Veeco Nanoscope IIIa)

Force versus distance curve

Atomic Force Measurements

The action at the AFM tip can be viewed as two components:

- a sensor that responds to a force

- a detector that measures the sensor response

Hooks law:

F = -kz where F is the force

k is the spring constant of a cantilever and

z is the vertical cantilever displacement.

The spring constant of a cantilever can be expressed as:

k = Et³w/4L³ where E is the elasticity modulus, which is a measure of

the restoring force upon extention,

t is the thickness of the cantilever.

In general, t is difficult to measure, however, it can be determined from the resonance frequency fr:

F_r = 0.162 (E/d)^1/2t/L²

where d is the density of the cantilever material.

The values of k are in the range from 0.01 to 50 N/m and are specified by the cantilever manufacturer.

AFM Tip

Sharpened AFM Tip End

Nanowires assembled from MoO_{3 Semiconductor
Metal Oxide}

AFM Image of a Monolayer Film of Bovine Serum Albumin

on gold EQCN electrode,

film thichness: 38 nm

The AFM/STM instrumentation has been funded by the NSF CCLI program, Award No. 0126402.

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