A Nanoparticle in the Mind of a Scientist

You have “ordered all things in measure, and number, and weight,” for the “whole world before you is as the least grain of the balance.” (From Wisdom 11:21-23)

Father Z had a charming post about how colloidal gold particles in stained glass windows can act as photocatalytic air purifiers. He said that if this is true it “really is just too cool.” It is true, gold particles in the glass can break down organic molecules.

Nanometer-scale materials were the focus of my doctoral research, and there’s even more to the coolness. This coolness was a major factor in my eventual conversion to faith in God – a nanoparticle seed of sorts, I suppose, that slowly took root, grew, and changed my heart and mind. Follow me…

First, Perspective

“Nano” means one-billionth (1/1,000,000,000). A nanometer is one one-billionth of a meter. A single blink of an eye is about one-billionth of a year.

One inch equals 25,400,000 nanometers.

Aluminum foil is about 16,000 nanometers thick.

Human hair ranges from 20,000 to 200,000 nanometers thick.

Fingernails grow ~1,000 nanometers every second.

Human red blood cells are 6,000 to 8,000 nanometers in diameter.

Particles in the nanometer world are bigger than atoms and simple molecules, but much smaller than objects we can see, thus, they often do not follow the laws of quantum mechanics, nor do they follow the laws of Newtonian physics. They instead exhibit unique properties, a realm of their own.

And the Stained Glass Windows?

Glass is made from molten silica (sand), and materials like soda ash, lime, potash, and lead oxide were added in medieval times so the sand would melt at lower temperatures. Furnaces were not able to reach temperatures to melt pure silica. Metal salts were added for color. For example, iron oxides give greens and browns, manganese oxides give amethyst or amber, cobalt oxide gives different blues, tin compounds give white, copper salts give reds, blues and greens. Standard pigments absorb certain light waves and reflect others, giving the solution a characteristic color.

Gold (and silver) salts do something different though. Tiny particles of gold aggregate and form a colloidal suspension in the molten glass. The electrons on the surface of these particles behave differently than bulk gold particles behave. A chuck of gold in your hand behaves like gold is expected to behave if cut in half, and even if the particles are small enough to make gold dust. But at the nanometer-scale, gold nanoparticles produce something called a surface plasmon resonance when sunlight irradiates them.

It works like this: Metals are like oceans of electrons swimming all around. On these surfaces of nano-scale particles, the light waves actually cause electrons to move back and forth together, and this is called the plasmon. These oscillating electrons emit their own light, the color depends on the frequency. Different sizes of colloidal gold emit different colors, but the deep blood red is the most popular.

An analogy: Imagine kids in a room. If you have stadium with 10,000 kids, it would be hard to get them all to move back and forth across the floor in unison. If you had, however, a classroom with 10 kids, it would be much easier. This is analogous to what happens in gold particles of the stained glass window. The electrons of gold particles, around 25 nanometers, resonate at the frequency of deep red when sunlight hits them, so they give off a deep blood-red color. (Source)

That is, in the medieval stained glass windows, the gold emits red light when sunlight shines on it, the magnetic field around it is what breaks down the organic molecules in the air. It looks like this.

(Note, the time intervals are in femtoseconds, and the femtosecond scale is even smaller than the nanometer scale. One femtosecond equals one millionth of one billionth, of a second. A femtosecond is to a second what a second is to about 31.7 million years. So what you see in the video is instantaneous to the eye. Mindboggling, no?)

If that’s not cool enough, consider one more thing. For this to work the particles have to all be the same size within very narrow limits. In the molten solutions the gold salt forms gold aggregates of consistent diameter at the nanometer scale, all the result of the laws of nature.

Trees – More Coolness

The average rate of energy capture by photosynthesis globally is about six times larger than the power consumption of human civilization.

Think that is fascinating technology? Remember, “technology” is a way of saying that we learned something about creation. All materials follow the laws of nature, even those yet to be discovered. Each tree is a magnificent “device” based on nano-scale “engineering”. My graduate work was aimed at replicating photosynthesis in the laboratory by growing polymer films on nanometer-sized particles. To get even a small fraction of the quantum efficiency of nature was, then, a publishable success. This is from the first page of my thesis in 1999 (seven years before I admitted I needed God).

We are only just beginning to understand how to control the structure and function of supramolecular structures and the role they play in composite materials. There are exquisite examples of this kind of engineering in nature.

Trees are composite materials composed of rigid components that give them structure and organization, as well as chemically active components that perform precise functions. Trees are shaped in such a way as to increase the surface area of the leaves, so that they can collect the most sunlight. This sunlight is used to process carbon dioxide and water into oxygen and molecular building blocks, which are used to construct roots, trunks, branches, twigs, and leaves.

Every tree makes leaves, and each leaf is more sophisticated than our highest technologies. Furthermore, all this is done without pollution, noise, or human labor, and the entire “device” is self-replicating.

Even then, as anti-religious as I was, I was compelled to admit that scientists are students learning from something greater, something beyond us all, and not a single scientist can deny this fact.

Tags: featured, nanometer, nanotechnology, stained glass windows

Category: Personal, Physics, Science