Professor Maria Hepel

EQCN Principles

State University of New York at Potsdam

Department of Chemistry

Stowell Hall

44 Pierrepont Ave.

Potsdam , NY 13676, U.S.A.

Tel.: +1.315.267.2267

Fax: +1.315.267.3170

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Raman Imaging and Spectroscopy Lab

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

Atomic Force Microscopy Lab

AFM operation

Tip interactions

Lectures to other Departments

Nanotechnology Lab


Quartz Crystal Nanobalance Lab

EQCN Principles

EQCN Setup




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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The Electrochemical Quartz Crystal Nanobalance (EQCN) technique uses quartz crystal vibrations to detect minute changes in the mass attached to the crystal.
  The frequency of vibrations is characteristic to the piezoelectric material (quartz), cut direction of the crystal, and physical dimensions.  For instance, the AT-cut quartz crystal wafers (35015' angle from c-axis) with thickness of 0.166 mm have the fundamental frequency: 10 MHz.

The AT-cut quartz crystals oscillate in the thickness shear mode.

The AT-cut quartz crystal wafers show a negligible temperature coefficient at room temperature, which makes it a convenient choice for routine measurements.

  The oscillations of a quartz crystal wafer are maintained by an electrical oscillation circuit tuned broadly to the band of the fundamental frequency of the crystal. 
  Any mass attached to the faces of a quartz crystal wafer influences the oscillation frequency, which can be measured.  The frequency shift is proportional to the mass rigidly attached to the crystal according the Sauerbrey equation:






Δf - change in the resonant frequency
Δm  - interfacial mass
n  - overtone number
fo - oscillation frequency at the fundamental mode
A  - surface area
μq = 2.947 x 1011 g cm-1 s-2  is the shear modulus
rq = 2.648 g/cm3  is the density of quartz


  For f0 = 10 MHz:
    k = 0.8673 ng/Hz



Nanoporous TiO2

for solar energy conversion and direct methanol fuel cells


Degradation of dye pollutants

Electron density surface

with potential map for dye pollutant Remazol Blue Black.  Decomposition of pollutants studied by photo-electrocatalytic method using TiO2, WO3, and MoO3 semiconductor electrodes

Quantum Conductance Monatomic Nanobridge Devices

studied using conductanc spectroscopy and AFM/STM

Oriented Single Crystal Quartz Wafer

used as a piezoresonator in sensors is able to detect  nanogram mass changes of monolayer films