Physics of Isotopologues
Lecture at the XXXV Heidelberg Graduate Days winter term 2015/2016
Isotopes and Isotopologues - from fundamental physics to everyday applications Is our food really originating from the places indicated on the label? Was the shroud of Turin actually used by Jesus? How cold was the last ice age in central Europe? Is the majority of the CO2 in our atmosphere due to fossil fuel burning? These questions could fully or partially be answered by isotopes and isotopologues.
Isotopes are atoms of one element that differ in the number of neutrons, whereas isotopologues refer to molecules that differ isotopically in their constituent atoms. Isotopes are ubiquitous for tracing and investigation of many physical and chemical processes in atmosphere, terrestrial and aquatic systems as well as in the biosphere. Oxygen isotopes are iconic examples in isotope studies that are used beyond applications in the hydrological cycle to infer temperatures of past climate periods by analysis of fossil carbonates. In addition, radioactive isotopes provide an internal clock for some physical and geological processes and constrain ages of many substances. In this context, the radioactive carbon isotope 14C is an important tracer that helps to determine the age of archaeological findings or to prove the authenticity of art work.
This course intends to give an introduction into the concept of isotopes and isotopologues. It includes the theoretical basis for the calculation of isotope and isotopologue abundances and investigates changes in their occurrence due to isotope exchange or fractionation processes. This course focuses on understanding of the physical mechanisms behind the observed effects and will be complemented by the illustration of the state-of-the art measurement methods. New advanced isotope techniques like multiply-substituted isotopologues ('clumped isotopes') and various traditional isotope methods exemplarily illustrate the wide range of promising applications in Physics and Earth Sciences.
Equilibrium fractionation and Rayleigh fractionation
Equilibrium and kinetic fractionation: some background
Multiply-substituted isotopologues. Measurement techniques