Tag Archives: pico

At the atto scale

Earlier this week, a team of Canadian scientists announced that they were able to observe a chemical bond as it broke. From the news item on physorg.com,

Scientists at the National Research Council of Canada (NRC) and the University of Ottawa (uOttawa) enjoyed a bird’s eye view of a chemical bond as it breaks.

The making and breaking of chemical bonds underlie the biochemical processes of life itself. A greater understanding of the quantum processes that lead to chemical reactions may lead to new strategies in the design and control of molecules — ultimately leading to scientific breakthroughs in health care and diagnostic medicine, quantum computing, nanotechnology, environmental science and energy.

The NRC-uOttawa team, led by Dr. David Villeneuve, achieved their feat using a technique developed several years ago at NRC in which an image was obtained of a single electron orbiting a molecule. In the current experiment, which is reported in the July 29th edition of Nature, scientists injected bromine gas into a vacuum chamber. There, an ultra brief ultraviolet light pulse caused the bromine molecules to separate into their individual atoms (a bromine molecule is composed of two bromine atoms).

A few femtoseconds later, an intense infrared laser pulse caused the molecule to emit an attosecond-duration X-ray burst that contained a snapshot of the atom’s position as the molecule fell apart and revealed how the electrons rearranged themselves.

The interference of the x-rays emitted by the two quantum states of the molecule was used to find the location of the atoms and to watch over a period of only 200 femtoseconds as it progressed from being a molecule to being two separate atoms. The experiment reached a precision below 500 zeptoseconds in clocking the emitted x-ray bursts. [emphases mine]

I’ve highlighted the units of measurement because they fascinate me in and of themselves. (I hadn’t encountered zeptos before although I have blogged about attoseconds,  May 13, 2009 posting).

Here are official designations starting with the nanoscale and dropping down to the smallest unit to date (from the US National Institute of Standards and Technology, Technology Services, Weights and Measures page),

nano, (n), meaning 10-9
pico, (p), meaning 10-12
femto, (f), meaning 10-15
atto, (a), meaning 10-18
zepto, (z), meaning 10-21
yocto, (y), meaning 10-24

If nano is the science of small, what will the others be?