During three months in 1997 Dr. Griscom was a Fulbright-García Robles Fellow at
Universidad Nacional Autónoma de México in Mexico City, where he chose to initiate ESR
studies of debris from the bolide impact 66 million years ago that created the 180-km-
diameter Chicxulub crater buried 1 km beneath México’s Yucatán peninsula (discovered by
others in the early 1990’s and now nearly universally believed to mark the event responsible
for the extinction of the dinosaurs). In 2001 Griscom extended his studies of these materials
while Professeur Invité at Laboratoire Minéralogie–Cristallographie de Paris at Université de
Paris 6, Paris, France. The culmination of this research was a 41-page chapter by Griscom,
V. Beltrán-López, K.O. Pope, and A.C. Ocampo in the 3rd volume (2003) of the Springer
monograph series, Impact Studies.
Using mostly the technique of electron spin resonance (ESR) spectrometry, Griscom was
responsible for the discovery and/or extensive characterization of nearly all known intrinsic
and extrinsic point defects in pure and B-, Ge-, and P-doped silica, alkali silicate and borate
glasses, and heavy-metal fluoride glasses, as well as characterizing fine-grained
ferromagnetic precipitates in glasses by ferromagnetic resonance (FMR). Of great
importance to both ESR and FMR, he derived apparently for the first time a closed-form
expression for the temperature dependence of the ESR (or FMR) intensity for any value of the
electronic spin S of isolated ions (or the calculated effective spin J of ferro-/ferri-magnetic
particles of any given diameter). His principal research interest since 1973 had been
radiation-induced point defects in amorphous silica (a-SiO2). His studies of radiation-
induced atomic hydrogen in a-SiO2 with hydroxyl impurities led him in 1986 to propose the
now-universally-accepted “hydrogen model" for the buildup of radiation-induced interface
states in metal-oxide-semiconductor (MOS) structures used for computer chips. This activity
catalyzed Griscom’s subsequent discovery and characterization of self-trapped holes
(STHs) in silica.
From 1993 through 1996, his research centered on radiation hardening of pure-silica-core
optical fibers for monitoring fusion-reactor plasmas, while from 1996 to 1999 he was
Principal Investigator on a Department-of-Energy-sponsored program to investigate
possible radiation-induced decomposition of candidate glasses for nuclear waste disposal.
Four years ago he reanalyzed his 1999 data for a unique then-17-year-old simulated
plutonium-immobilization glass containing selected amounts of highly radioactive isotope
Pu-238, and his long article on this subject was subsequently published in the Journal of
Non-Crystalline Solids, as was also a long review and synthesis of trapped-electron centers
in irradiated pure and silica glasses. Download one or both here.
In 2000 Griscom devised fractal kinetics formalisms that he used to analyze the production
and thermal decay of radiation-induced defect centers in both pure and germanium-doped
silica-core optical fibers, discovering in the process some totally unexpected, and
undoubtedly useful, empirical rules for the dependencies of the rate constants on dose rate.
Two years ago he gave the lead-off lecture at the conference Si02-2012 held in Hyères,
France, entitled "A New Perspective on Defect Centers in Ge-Doped Silica (and the Structure
of Silica Glass Itself!) from Re-Analysis of Old Data." This PowerPoint can be downloaded
here, together with a recent publication on this subject.
David L. Griscom Ph.D. is a Research Physicist, retired January 2001 from Naval Research
Laboratory (NRL) in Washington, DC, after 33 years service, including 2 years as half-time
Program Manager at the Defense Advanced Research Projects Agency in Arlington, VA.
He is a Fellow of the American Physical Society, the American Association for the
Advancement of Science, and the American Ceramic Society; and he was a Fulbright-García
Robles Fellow at Universidad Nacional Autónoma de México in Mexico City in 1997.
Between 2000 and 2004, Griscom held visiting professorships of research at the
Universities of Paris-6&7, Lyon-1, and Saint-Etienne, France, and Tokyo Institute of
Technology. He was Adjunct Professor of Materials Science and Engineering, University of
Arizona from 2004 to 2005. The winner of the 1993 N.F. Mott Award sponsored by the
Journal of Non-Crystalline Solids, the 1995 Otto Schott Award offered by the
Carl-Zeiss-Stiftung (Germany), a 1996 Outstanding Graduate School Alumnus Award at
Brown University, and the 1997 Sigma Xi Pure Science Award at NRL, Griscom is principal
author of 113 of his 195 published works, a body which is highly cited by his peers
according to his score (h=52) on the recently devised
| David L. Griscom, Ph.D. Physicist, Consultant
Long-Term Research Specializations and Accomplishments
Recent Forays into Impact Geology
|Footnotes to photos at top:
(2000) Dave Griscom and Pavle Premovic (Director, Laboratory for Geochemistry,
Cosmochemistry & Astrochemistry, University of Nis, Serbia) with the ESR spectrometer
that they shared at Universite de Paris-6.
(2001) Dave at Planetary Society expedition to Chicxulub crater ejecta outcrops, Albion
(2002) Dave in practice jersey of Mandai Memorials Ice Hockey Club, Tokyo.
(2007) Dave at GSA Penrose Conference on The Late Eocene Earth, Parc del Conero, Italy
In August 2003, Griscom and eight colleagues from laboratories in the U.S., France, and
Japan published in the proceedings of the international conference “Natural Glasses-4” an
unprecedentedly thorough materials-science characterization of the iron-oxide-welded
quartzite pebbles and cobbles of “upland deposits” of eastern Virginia, southern Maryland,
and Washington, DC, concluding that these rocks have no other interpretation than as being
ejecta from the 35.5-million-year-old, 90-km-diameter Chesapeake Bay crater, discovered
by scientists at the U.S. Geological Survey in the early 1990’s. (Reprints of this paper
replete with extensive color photography are available from the author on request.) Griscom
presented his purely geological evidence for the same conclusion at numerous geological
meetings and seminars over the past 15 years, including the 2007 Geological Society of
America Penrose Conference on The Late Eocene Earth, held in Monte Cònero, Italy. Very
recently he published his comprehensive article on this subject in the new European
Geosciences Union journal Solid Earth Discussions.
Paris, 2000 Belize, 2001 Tokyo, 2002 Italy, 2007
or go here to view his LinkedIn profile.