At this point, St. Patrick’s Day in America is probably more of an insult to the Irish than a celebration of anything, so before gulping down another shamrock drawn in Guinness foam, take a few minutes to see how researchers were able to etch a 200-nanometre shamrock onto a Trinity College lapel pin.
Researchers at the Advanced Materials and BioEngineering Research (AMBER) centre etched the nano-sized shamrock onto a 150 micrometer-wide harp string on the pin using their Helium Ion Microscope. For a sense of scale, a human hair averages about 100 micrometers wide, and the researchers say that 500 of these shamrocks could fit on a human hair—the stem is 200,000 times smaller than a grain of salt. Just as descriptions of outer space traffic in unimaginably large scales, all descriptions of the nano-scale seem to inadequately describe just how small it is. A cell's membrane is 10 nanometres thick. A sugar molecule is about a nanometre wide.
Helium ion microscopy works by sending high-intensity ion currents from a very sharp needle—the tip of the AMBER’s needle is just three atoms. Under low temperatures and in the presence of helium gas, high positive voltage is applied to the needle. This forms an intense electric field that strips electrons from helium atoms, and the resulting positive ion is repelled from the needle’s tip, creating a super-bright, super-focused ion beam.
The AMBER can take high-resolution images that are less than a nanometre, which in a world of single-atom-thick graphene means that making a tiny shamrock is more than just an invisible pleasantry. I mean, the shamrock is that, but if we want to have super-fast graphene processors, it means manipulating things on the smallest of scales.
So in between decking yourself out in green beads and regurgitating green beer and corned beef all over the sidewalk, take a moment to remember that Ireland isn’t just a country of drunken louts—the tiniest shamrock-sporting pin was presented to Dr. Garret A. FitzGerald Friday by “The Wild Geese Network of Irish Scientists,” for FitzGerald’s work “in the area of cardiovascular health and in particular the implications of pain medicines on cardiac systems.” With that respectfully noted, it’s impossible to ignore how much that organization invoking the “Wild Geese” in their name reminds me of liquor.