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Using fluorescence correlation spectroscopy to observe a single molecule


Reasons to focus into a small volume element
Manfred Eigen Scientist
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Why do we focus into a small volume element? Well, first of all, the noise will go down. The noise by light which is reflected and whatever comes in... scattering of light... so that, of course, would be very lethal if you want to see small fluctuations. But the second reason to take a small volume element is to make it so small that no molecule you want to observe is inside the volume element, it's simply too small for it... for having steadily one molecule present. As I said already, the property we want to observe is fluorescence. What is fluorescence? Well, fluorescence is a response of the molecule to electromagnetic radiation, so in other words you shine in light, quanta they are absorbed, the molecules get to an excited state, and emit again a photon when they fall back into their current state. Now of course the emitted photon has to have almost always less energy than the exciting light, so the fluorescence is always with respect to the exciting light... is shifted to longer wave lengths... but it's shifted far enough to longer wave lengths that you can easily record without seeing the reflections of the exciting light.

Nobel Prize winning German biophysical chemist, Manfred Eigen (1927-2019), was best known for his work on fast chemical reactions and his development of ways to accurately measure these reactions down to the nearest billionth of a second. He published over 100 papers with topics ranging from hydrogen bridges of nucleic acids to the storage of information in the central nervous system.

Listeners: Ruthild Winkler-Oswatitch

Ruthild Winkler-Oswatitsch is the eldest daughter of the Austrian physicist Klaus Osatitsch, an internationally renowned expert in gas dynamics, and his wife Hedwig Oswatitsch-Klabinus. She was born in the German university town of Göttingen where her father worked at the Kaiser Wilhelm Institute of Aerodynamics under Ludwig Prandtl. After World War II she was educated in Stockholm, Sweden, where her father was then a research scientist and lecturer at the Royal Institute of Technology.

In 1961 Ruthild Winkler-Oswatitsch enrolled in Chemistry at the Technical University of Vienna where she received her PhD in 1969 with a dissertation on "Fast complex reactions of alkali ions with biological membrane carriers". The experimental work for her thesis was carried out at the Max Planck Institute for Physical Chemistry in Göttingen under Manfred Eigen.

From 1971 to the present Ruthild Winkler-Oswatitsch has been working as a research scientist at the Max Planck Institute in Göttingen in the Department of Chemical Kinetics which is headed by Manfred Eigen. Her interest was first focused on an application of relaxation techniques to the study of fast biological reactions. Thereafter, she engaged in theoretical studies on molecular evolution and developed game models for representing the underlying chemical proceses. Together with Manfred Eigen she wrote the widely noted book, "Laws of the Game" (Alfred A. Knopf Inc. 1981 and Princeton University Press, 1993). Her more recent studies were concerned with comparative sequence analysis of nucleic acids in order to find out the age of the genetic code and the time course of the early evolution of life. For the last decade she has been successfully establishing industrial applications in the field of evolutionary biotechnology.

Tags: small volume element, fluctuations, fluorescence, electromagnetic radiation

Duration: 1 minute, 47 seconds

Date story recorded: July 1997

Date story went live: 29 September 2010