Animation - Engineers Develop New Chemical Sensor
Based on Experimental Physics Breakthrough
This animation requires
the FlashPlayer version 5 Plug-in. Click
on the flash player icon to get your copy
of the FlashPlayer Plug-in.
The following is a text description of the animation:
"The animation begins by showing a dumbbell shaped
oxygen molecule (chemical formula O2) landing on a
rectangular array of silver atoms. When the oxygen
molecule lands, the silver atoms vibrate in response
and radiate heat energy.
Text: Previously, scientists thought nearly all energy
from atoms adhering to a metallic surface caused vibrations
that gave off heat.
However, scientists have recently discovered that nearly
all interactions between molecules and metal surfaces
produce energized electrons . . .
The animation now shows oxygen molecules landing on
the array of silver atoms, but instead of vibrations,
tiny electrons shoot away from the sites of chemical
interaction.
Text: A chemical reaction occurs when the gas molecule
makes contact with the surface atoms of the metal.
Electrons from the metal atoms are then released.
The animation now shows a device, called a Schottky
diode sensor, that is made of three unique layers.
The top layer is a silicon chip that has been coated
with a thin layer of silver film. The middle layer
is slightly larger and thicker and it is labeled as
a heater. The bottom layer is the largest and thickest,
and it is labeled as a Peltier cooler. The Schottky
diode sensor is hooked up to an ammeter, a device
that measures current.
Text: Scientists can detect and study the current produced
by the electrons with a sensor known as a Schottky
diode sensor. The current has been dubbed "chemicurrent.'
The basic parts of a Schottky diode sensor are shown
here as part of a simple circuit. The device on the
right is an ammeter, which measures current.
The animation now shows oxygen molecules flying around
and landing on the surface of the Schottky diode sensor.
Text: Oxygen gas molecules (comprised of two oxygen
atoms bonded together) make contact with the thin
silver film and produce chemicurrent.
The animation now shows propane molecules flying around
and landing on the surface of the Schottky diode sensor.
Text: Different gases for a given type of metal produce
different amounts of current. Here, propane gas interacts
with the sensor, producing a stronger current.
National Science Foundation
Office of Legislative and Public Affairs
4201 Wilson Boulevard
Arlington, Virginia 22230, USA
Tel: 703-292-8070
FIRS: 800-877-8339 | TDD: 703-292-5090