A world of surfaces big and small

What we see of our world are surfaces of matter touched by light. Surfaces define the shape and texture of every rock and creature on this planet, and light illuminates them allowing us to see shapes, textures, and colors. We are all aware that light is one of the foremost foundations of our world; it provides energy and sustains life. Understanding the interaction of surfaces with light is, therefore, essential in understanding the many workings of our planet. As creatures of the sun, we tend to understand and describe things through images, a product of the interaction of light and surfaces.

These days, our view of our world has gone all the way down to the nanometer resolution of things with the advent of powerful microscopes and coherent light sources, which we use as extensions to enhance our sense of visual perception. (A nanometer is a billionth of a meter.) Our eyes, our biological built-in camera, have an angular resolution of approximately one arc minute, which means we can see objects as tiny as 0.1 millimeter across without difficulty. Our eyes can observe motion as long as it is not too fast or too slow. Anything that moves through our visual field faster than five seconds will be seen as a blur, and motion that involves durations longer than two to three seconds are seen as stationary.

Therefore, our naked eye is good enough to see a tiny freckle on a child’s cheek, differentiate one strand of hair from another, or watch Manny Pacquiao’s insanely fast “south pawing.” What we cannot perceive with our sense of sight is what we deem as invisible, things or events that require extra magnification, extra time resolution to observe since they are too little, too slow or too fast for our eyes to decipher. Examples are dust mites that lurk in the pores of our skin, the motion of plants looking for sunlight, the flutter of hummingbird wings, and man-made micro-machinery, which we use in our satellites and our little handheld devices.

Surface phenomena involve events at the interfaces of various phases of matter, a region in space where gas touches liquid, liquid touches solid, gas touches solid, vacuum touches liquid, and so on. Surface science is the study of these events at these particular regions in space where processes begin and reactions occur. Surface macroscopic events are what capture our attention, occurrences such as bubble formation, water striders walking on water, post-its re-adhering to paper, the curdling of milk, or the rusting of galvanized roofing. Making sense of these events, however, is best described and understood by taking a stroll to the littlest of lanes. Viewing events at the nanometer scale, at a few monolayers deep, even at the atomic or molecular levels.

At this degree of observation, surface events are well viewed and imaged, providing very good explanations of what is happening at the macroscopic level. The “nano” or the “micro” making sense of the “macro.” Knowing what is happening at the atomic or molecular level may give us the capability to remake these surface events or prevent them from happening depending on what we aim to achieve. Tools such as surface specific microscopes and spectroscopes of various sources whether lasers, electrons or ions will help us observe these events. These tools will allow us to probe surface phenomena, and observe things, which our own eyes cannot make out. They can help us understand certain occurrences such as how body implants resist fouling, how dental fillings adhere to the tooth enamel, how paint absorbs air pollutants, how edible coatings prevent fruits from rotting, how F1 tires resist wear and tear, how solar cells convert sunlight to electricity, how detergents remove soils from fabrics, and so many more “hows.”

Research areas under surface science include catalysis, electrochemistry, colloidal science, semiconductor device fabrication, fuel cells, corrosion, adhesives, tribology (friction studies), surface modification (coatings, self-assembled monolayers, surface functionalization), and sensor development.

The history of surface studies goes way back to the time of the Roman scholar Pliny the Elder, who described the phenomenon of oil spreading on water in ancient times. The application of catalysis started as early as the 1800s when Dobereiner created his portable lighter, at the same period that daguerreotype photography was popularized. Tribology and friction studies erupted with the industrial revolution, although Leonardo da Vinci had already done some earlier work.

In the late 50s, solid-state electronics and affordable ultrahigh vacuum systems were developed due to interests in space exploration, and this led to the advancement of surface analytical techniques, which then led to the understanding of surface macroscopic events at the molecular level. The invention of lasers in the 60s also led to the advancement of surface analytical tools which can be used in ambient conditions. Surface science has grown since then, delving into more diverse surface studies. In 2007, Professor Gerard Ertl bagged the Nobel Prize for Chemistry for his work on surface chemistry; finally the impact of this field in society had been recognized.

In the Philippines, the field of surface science is starting to flourish and be recognized in the scientific community. Very recently, the Department of Science and Technology-ADMATEL (Advanced Device and Materials Testing Laboratory) was inaugurated. The laboratory houses several state-of-the-art surface-specific analytical tools. High-tech microscopes that operate in ultrahigh vacuum conditions, which are capable of nanometer resolution probing, are contained in Class 100K cleanrooms.

The Institute of Chemistry, University of the Philippines-Diliman opened its ANSER (Advanced Nanomaterials, Sensor and Environmental Research) facility in 2012, housing several surface instrumentations. At the Philippine National Institute of Physics, a surface-specific, non-linear optical microscope spectroscope is being developed under the support of the UP Balik Ph.D. Program of the UP System under the Office of the Vice President for Academic Affairs (OVPAA). This instrument will allow for surface-specific molecular level probing at ambient conditions using ultrafast lasers as light source. These facilities will allow a few surface scientists in the country to perform extensive work on this particular field.

Surface science is clearly a very important field of study particularly in addressing the energy crisis, environmental concerns, health issues, and industrial development impediments. Definitely, it will require a lot of support and nurturing, both from the government and the private sector.

Perhaps all we need is a little more comprehension of things we cannot readily see and visualize. A little change of scenery, a bit of magnification and resolution, a little push into a clearer view of things to lead us into a straighter path of understanding. Next time, when we peek from our windows at sunrise, we can think of a world of surfaces, full of mysterious events, both creative and destructive, at the smallest possible scale, unseen by most of us, waiting to be explored and understood, shaping our way of life.

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References:

Frankel, F. and G.M. On the Surface of Things. San Francisco: Chronicle Books, 1997.

Land, M.F.J. “Motion and vision: why animals move their eyes” in Journal of Comparative Physiology 185, 1999: 341-352.

Salzwedel, M. “How fast can the eye see?”. http://www.ehow.com/how-does_5188053_fast-can-eye-see_.html.Demand Media Inc., 2013.

Somorjai, G. A. Introdution to Surface Chemistry and Catalysis. New York: John Wiley and Sons, 1994.

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The author’s research centers on the characterization and imaging of surfaces and surface phenomena using non-linear optical microscopy/spectroscopy, and other more classical surface techniques. 

She earned her Ph.D. at the University of Houston, Texas and did her post-doctoral fellowship at Northwestern University-Evanston. She is currently an associate professor at the Institute of Chemistry, National Science Complex, UP-Diliman, teaching general and physical chemistry courses. She is also a recipient of the UP Balik Ph.D. Program and the DOST Balik Scientist Program.

Her current research projects are:

(1) The Synthesis and Surface Characterization of Room Temperature Ionic Liquids for Gas Capture Technology Development; Research Associate/Graduate Student: Monica Berenguel; Funding Agency: Natural Sciences Research Institute.

(2) Development of A Convertible in Transmission-Reflection Mode Femtosecond Second Harmonic Generation Microscope/Spectroscope (TR-SHGM/TR-SHGS) for Surface Studies;

Research Associate/Graduate Student: John Rafael Granada Collaborators from the Femtosecond Laser Facility, PNIP: Elmer Estacio, Ph.D., Arnel Salvador, Ph.D.; Funding Agency: UP Balik Ph.D. Program, UP-OVPAA.

(3) Application of VISSER (Versatile Instrument System for Science Education and Research) to Carbon Capture Measurements; Research Associate/Graduate Student: Dwight Angelo Bruzon, Program Leader: Giovanni Tapang, Ph.D.; Funding Agency: EIDR GRANT, UP-OVPAA and DOST.

E-mail her at [email protected].