[pct-l] Squeeze a rock, recharge your batteries

[hankm at mtinet.com (Hank Magnuski)]

There was a thread recently on the list related to

 " Light Phenomena on Oriflame Mtn.... "

The following meeting notice and observations caught my attention.

Hank

---------- Forwarded message ----------
Date: Fri, 16 Apr 2004 22:36:12 -0700
From: Paul Robb <probbsprint@earthlink.net>
To: probbsprint@earthlink.net
Subject: April 2004 Optical Society Meeting Notice

Please forward this notice to anyone that might find it of interest.

www.OSNC.org
Visit our WEB site for the latest Society events
Tuesday April 20, 2004 @ 8:00 PM
@ PARC, 3333 Coyote Hill Blvd., Palo Alto, CA 94306
Auditorium

Infrared radiation from stressed rocks

Friedemann Freund
San Jose State University, San Jose, CA
(650) 604-5183
ffreund @ mail.arc.nasa.gov


The speaker:  Friedemann Freund is a professor at San Jose State
University

The talk:  Images taken with National Oceanographic and Atmospheric
Administration and NASA satellites reveal a strange phenomenon: Prior to
a major earthquake, the areas where stresses build up deep in the
underground often seem to heat up for a few days. Freund had the idea
that what these satellites record as thermal anomalies may in fact be
caused by a form of IR luminescence involving electronic charge
carriers. In this model, the charge carriers become activated when rocks
are stressed to the point of plastic deformation.

To test this, Freund applied sudden, short stresses to rocks by shooting
them with a crossbow and with NASA's Ames Vertical Gun Range, a
two-stage, light-gas gun that can accelerate 0.25-in. projectiles to
velocities  of approximately 6.5 km/s. The impacts with the projectiles
created small but intense deformations at the impact points and freed a
cloud of electric charges that had existed in the rocks in an
electrically inactive, dormant state. The charge clouds propagated at
several hundred meters per second, even speeding through portions of the
rocks that had not experienced stress.

 There were also some high-frequency components, in the range of radio
frequencies, which probably arise from the buildup of electric fields at
the rock surface; in particular, at the corners and edges. These local
fields are so  high that they can produce corona discharges accompanied
by visible light.

Intrigued by these observations, Freund squeezed rock samples in a
hydraulic press until they failed. At first, he used slabs of granite,
which is common in the Earth's crust. The stone contains large amounts
of quartz,  which develops an electric charge when squeezed. Next, he
used quartz-free anorthosite, a rock composed almost entirely of
labradorite, a
feldspar known for its iridescence. Only the central part of each block
was compressed, leaving the periphery largely stress-free. During the
experiments, he measured the emissions from the rock surface with an IR
spectrophotometer from ABB Inc. of Quebec.

Freund recorded a specific IR emission from the rock surface, 10 to 20
cm away from the point where the rock was being squeezed. The emission
occurs so rapidly, he explained, that it cannot be propagating heat. Its
spectrum has several components, including a narrowband one that occurs
where theory predicts the emission band should be from the recombination
of the charge carriers.

More experiments are planned to study the phenomenon in greater detail.
Although he is unwilling to make any firm statement at this time, he
believes that the discovery of the dormant electronic charge carriers in
rocks, which can be awakened by stress, opens the door to a better
understanding of geological phenomena from the thermal anomalies in
satellite images to the "earthquake lights" photographed in Japan.

The Dinner:  Dinner will be held at 6:00 P. M. at the Olive Garden, in
Palo Alto on El Camino Real, one block north of Page Mill Rd.  The
address is 2515 El Camino Real, phone is 650-326-5673.  Come on out and
meet the speaker and your colleagues in the Optics field.

Paul Robb President
Probbsprint @ earthlink.net

Michael Gersonde Vice President
elan23 @ sbcglobal.net

Paul Griffiths Vice President, Meetings and Membership
Paul113 @ ix.netcom.com

Bob Dahlgren, Director at Large
Bob @ svphotonics.com

Ram Sivaraman, Director, employment
Ramsivaraman @ Yahoo.com

If you haven?t renewed your 2004 OSNC membership, why not take a moment
to do it now?  Either send us the invoice you've already received or go
to our Web site (www.OSNC.org), print the renewal form, and send it to

OSNC
101 First Street
Box 226
Los Altos, Ca 94022

Or, just send us a business card with your name, e-mail address, and
mailing address.

It?s only $15 per year.

Thanks for joining us!

OSNC members:  take a look at the web site and interesting talks
sponsored by our colleagues in the IEEE Lasers & Electro-Optics Society
(LEOS):
http://www.silicavalley.com/