update.340 (fwd)

[Jim Choate <ravage@ssz.com>]

Forwarded message:
>From physnews@aip.org Wed Oct  8 14:08:52 1997
Date: Wed, 8 Oct 97 09:47:35 EDT
From: physnews@aip.org (AIP listserver)
Message-Id: <9710081347.AA08262@aip.org>
To: physnews-mailing@aip.org
Subject: update.340


PHYSICS NEWS UPDATE                         
The American Institute of Physics Bulletin of Physics News
Number 340 October 8, 1997 by Phillip F. Schewe and Ben Stein

TURNING ONIONS INTO DIAMONDS.  Nano-diamonds can
be created without high pressure by squeezing carbon "onions"
(nested buckyball-like structures) with ion beams.  Graphite
material can be made into diamond the hard way, with the use of
high pressure (above 10^6 atmospheres), high temperature, and
the use of catalysts.  But recently scientists have been able to
bombard carbon onions with electron beams and now ion beams
as well, and have been able to convert the onions almost
completely into diamonds, up to 100 nm in size.  Researchers at
the Max Planck Institute in Stuttgart (Florian Banhart,
banhart@wselix.mpi-stuttgart.mpg.de) use a beam of neon ions
to pelt the onions, which act like miniature pressure cells.  With
larger ion accelerators, one should be able to make macroscopic
amounts of irradiation-induced diamond.  (Experimental work:
Wesolowski et al., Applied Physics Letters, 6 Oct. 1997; theory
paper (Zaiser and Banhart) upcoming in Physical Review Letters;
figure at www.aip.org/physnews/graphics.)

MOLECULAR HYDROGEN SHOULD BECOME
SUPERFLUID if placed on the right surface, say physicists at the
University of Illinois (David Ceperley, ceperley@ncsa.uiuc.edu). 
Superfluids, substances that flow without friction, are few in
number: liquid helium-4, special gases of rubidium and sodium
atoms (in the form of Bose-Einstein condensates), pairs of
helium-3 atoms, and pairs of electrons (which flow through
superconductors).  The trouble with getting hydrogen molecules
(H2) to become superfluid is that they are all too ready to
combine with each other into H2 solids. By laying them on a
silver substrate and by salting them with a pinch of alkali metal
atoms, the H2's should be able to resist the tendency to solidify
all the way down to zero temperature.  At 1.2 K they would
become a superfluid, the Illinois theorists predict.  They believe
this can be carried out over the next year, after which
experimentalists could explore unique hybrid superfluids, such as
H2/He-4 mixtures.  (M.C. Gordillo and D.M. Ceperley,
Physical Review Letters, 13 Oct; see figure at
www.aip.org/physnews/graphics)

A POLYMER THAT CAN TRANSFER ENERGY BETWEEN
DIFFERENT LIGHT BEAMS has been demonstrated by
researchers at UC-San Diego (W.E. Moerner, 619-822-0453),
opening possibilities for inexpensive and easily manufacturable
"optical transistors" that can amplify or attenuate a light beam. 
The San Diego polymer is an example of a "photorefractive"
material, a material that adjusts its structure and electronic
properties when two or more light beams combine on it to form
an interference pattern.  On these materials, light from one beam
can bend in such a way as to bounce back in the direction of a
second beam, adding energy to it.   Inorganic versions of these
materials exist, but they are difficult to make and can cost
thousands of dollars for a tiny cube. Moerner constructed a
polymer whose three main components carried out essential tasks:
buckyballs offer electrons, poly (n-vinyl carbazole) (PVK)
molecules carry these electrons along their backbone, and
PDCST molecules stretch or contract, changing the way light
bends in these regions.  The researchers demonstrated a "net
gain" of about 5, in which one of the laser beams shining on the
material gained energy.  These materials have numerous possible
applications, including correcting distorted images.  (Science, 25
July.)