History Main / SharpenedToASingleAtom

* The titular character from RurouniKenshin also does this with a knife (cutting a large radish in half and then pushing it back together) to check if it was made by a legendary swordsmith.

* ''TheDarkSideOfTheSun'' by Terry Pratchett features a monomolecular blade (which shatters when swung against a villain gifted with luck manipulation).
** They came up again in his {{Discworld}} series - both Death's scythe and sword have edges one molecule thick.

* Cerberus Phantoms (ninja mooks) in ''VideoGame/MassEffect3'' carry monomolecular swords.

* In ''BatmanBeyond'', Assassin Curare uses a monomolecular sword that effortlessly cuts through anything standing in the way of her swings.

* Science time: contemporary nanotechnology is actually capable of creating blades like this, but, with a few exceptions (see below, mostly), not ''sustaining'' them. Regular blades go dull; an edge that can be measured in atoms becomes an ordinary knife very quickly if those atoms do not have ''very'' strong atomic and intermolecular bonds.

{{Absurdly Sharp Blade}}s are often the weapon of choice for dashing heroes and dastardly villains in works of science fiction. Sometimes, though, a mere AbsurdlySharpBlade lacks sufficient punch--the character needs a blade which is SharpenedToASingleAtom!

Such blades possess extraordinary cutting abilities because the width of their edges can be measured in ''atoms'', usually to exactly one molecule or one atom. Typically, the blade thickens to a nearly normal-sized spine, but occasionally the entire blade is impossibly thin, in which case it may be completely invisible when seen edge-on.

Most often seen with knives or swords, but occurs from time to time with RazorWire, too.

Sometimes, the edge, or the whole blade, will be referred to as ''monomolecular''.

Blades SharpenedToASingleAtom are popular in SpeculativeFiction, most often in ScienceFiction.

This is a subtrope of AbsurdlySharpBlade.

Please keep examples to instances where a '''specific''' (very small) '''width''' is given for the blade's edge; if no specific measurement is given, the example belongs under AbsurdlySharpBlade.

Sometimes, the edge, or for that matter, the whole blade, will be referred to as ''monomolecular''.

Most often seen with knives or swords, but occurs from time to time with RazorWire, too.

* To prepare a slide for an electron microscope, a diamond blade is used to get a less-than-paper-thin slice. Once properly sharpened, it's about a hundred atoms wide or so, and it will slide through your hand as easily as through the air.
** Both Diamond blades and freshly broken glass blades are used to prepare slides for electron microscopy. Glass blades are sharper (and cheaper) but wear out after a few dozen slides, diamond blades last almost forever.

** In the short story [[http://tvtropes.org/pmwiki/pmwiki.php/HoYay/StarWarsExpandedUniverse Side Trip]], Jodo Kast, who is actually Thrawn in disguise, gives one to [[spoiler:Corran Horn]].

* Also Happens in the ''StarWars'' short story [[http://tvtropes.org/pmwiki/pmwiki.php/HoYay/StarWarsExpandedUniverse Side Trip]] where Jodo Kast, who is actually Thrawn in disguise, gives one to [[spoiler:Corran Horn]].

* Blades like this make an appearance in the Star Wars Expanded Universe novel ''Specter of the Past'' by Timothy Zahn, in the form of the Xana "molecular stiletto." Depicted somewhat realistically, in that it's described as being capable of cutting through almost anything, but is extremely delicate, with even the carefully executed cutting of a hard surface (such as a lock) being as likely as not to ruin the blade.

** The [[OurElvesAreDifferent Eldar]] Harlequin units have a weapon called The Harlequin's Kiss, which is a molecule thick whip yards long, delivered in a neat bundled package with a punch, at which point it unfurls, and then snaps back into the delivery device.
*** And they deploy this weapon by shoving the neat bundled package [[NightmareFuel right into your mouth]] (with the open end down your throat), thus the name.

* Matthew Mantrell wields one in at least the first book of ''A Wizard In Rhyme''.

** They came up again in his {{Discworld}} series - both Death's scythe and sword have edges one molecule thick.
*** It's unclear if they are that thin, or if it's simply the nature of what they do. They ARE both transparent (and entirely disappear in places where there is no death), and they are described as cutting apart individual molecules of air.

* ''{{Andromeda}}'' once depicted a "monomolecular lash", basically a ''whip'' that can cut through anything and has to emit a glow in order for anyone to see it. Since it cuts through its wielder as easily as anything else, it's exceedingly difficult to master and expert users of it are very rare.

** That's a bit of oversimplification. The ''working part'' of this sensor (which is called simply ''the tip'' — gotta love the simplicity) is indeed a single atom, but the slope of the tip doesn't extend all the way to it. Instead it terminates in a relatively large dome shaped end with the radius of ~10 nm (or, in layman's terms, about 100-200 atoms wide). Ideally this dome must be exactly hemispherical, so only the topmost atom creates the tunneling current, but in real life the tip preparation is something of a LuckBasedMission, so you often end with a so called "double tip" or other goofs. On the other hand, 100 atoms, while not one, still ''are'' absurdly sharp. Even if the slightest ''sideways'' force bends the tip end, if you apply it head on you can easily pierce your finger through.

* The Subtle Knife of the ''HisDarkMaterials'' trilogy works like this. It can also cut holes between dimensions when used properly.

* Single-layer graphene is probably the sharpest blade that can be made with conventional matter. It's a single atom thick, thinner than you can get pretty much any substance without distributed electron orbitals to stiffen it, and it's essentially the strongest material known that operates on that scale. Per unit area, it's stronger than diamond, though diamond is superior at greater thicknesses, due to graphene's weak inter-layer binding.

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* The second book of the ''His Dark Materials'' trilogy introduces us to the eponymous Subtle Knife, a blade than can cut through anything to the point where it can cut holes through to other worlds.

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* A Scanning Tunneling Microscope has a sensor which is a needle coming to a tip which consists of a single carefully placed atom.[[/folder]]