Scientists have now performed an MRI...on
a single atom.
The world’s smallest MRI, how cute is that?!
This level of resolution is a breakthrough
for the world of microscopy, and has potential
applications in all kinds of fields, from
quantum computing to drug development.
MRI stands for magnetic resonance imaging,
and though it may be able to see things inside
your body on the more macro scale, this picture
is actually the result of tiny shifts in your
protons.
As the name implies, an MRI scanner creates
an extremely strong magnetic field around
whatever it’s trying to image.
This temporarily re-aligns the protons in
your body with that magnetic field.
Then the machine pulses the sample or the
patient with a different current—a radiofrequency—which
pulls the protons slightly out of their alignment
with the magnetic field.
After the brief radiofrequency pulse is over,
the protons snap back into alignment with
the field, kind of like a rubber band that’s
stretched between two fingers snapping back
into place after you pull it.
The energy that’s released as the protons
move back into place with the magnetic field
is what is detected and visualized by the
machine.
Different tissues are distinguishable from
one another because their protons can take
different amounts of time to snap back into
place, and release different amounts of energy
when they do.
But that’s on the scale of the human body,
full of protons.
So, how do you take something like that and apply
it to a single atom?
If you immediately pictured a tiny, miniature
version of an MRI machine, you’re not alone,
I’m right there with you—but no, that’s
not how it works.
Instead, the researchers who created this
technique altered an existing microscopy instrument—a
scanning tunneling microscope (STM).
STMs involve bringing the tip of the microscope
into contact with metal atoms at the surface
of a material.
The electron cloud of the atoms on the tip
of the microscope interact with the electron
cloud of the atoms on the surface of the material.
When voltage is applied to the tip, those
electron clouds become connected by an electric
current.
Then the electrons of the atoms in the material
‘quantum tunnel’ to the tip of the microscope,
giving you a pretty beautiful picture.
This kind of imaging is highly detailed, and
at its best gets down to about .1 nanometers,
or an angstrom—which is definitely atomic scale.
But there’s only so much information an
image like that contains.
Enter: the atomic scale MRI.
This joint research team from several institutions
around the world applied iron atoms to the
tip of a scanning tunneling microscope, generating
a magnetic field.
Further application of a radiofrequency then induced changes in the spin state of the atoms in
the material.
The difference in spins between the tip of
the microscope and the sample material, gives
us a picture of the atom.
This means big things in the world of tiny
science.
The atomic MRI can image atoms on a sub-angstrom
level, smaller than ever before.
It can tell us about their magnetic properties
and spin structures, which you might imagine
could be hugely useful in quantum physics...particularly
quantum computing.
This kind of computing relies heavily on the
spin dynamics of particles, and being able
to understand and potentially even organize
individual atoms with this technology could
drive unprecedented advancements in quantum tech.
Atomic-scale peeks at magnetic properties
of molecules might help us with science on
the nanoscale in fields like biology, too—this
new technique may help us see how proteins
fold, something that could lead to the development
of better medicines.
And while it’s very exciting to think about
the possibilities of this new tech, it’s
not the most easy-to-use apparatus as of yet.
The microscopic MRI uses an ultra-high custom
vacuum, requires cryogenic temperatures, and
has so far only looked at very specific kinds
of materials.
But the researchers hope to keep developing
their tiny MRI to be even simpler to use,
continuing to see even more than ever before.
If you want even more on exciting developments
in microscopy, check out this video over here,
and if you have another technology you want
us to cover, let us know in the comments below.
Make sure you subscribe to Seeker to know
when we peer even further down into the details
of the universe, and as always, thanks for
watching.
We’ll see you next time.
