In September 2000 the University of Bayreuth Germany hosted the Fourth International Meeting
on Thermodi?usion (IMT4). TheIMTconferenceswerebornfromtheideaofbringingtogetherresearchers in
the ?eld of thermodi?usion. Under the auspices of the European Group of Research in
Thermodi?usion(EGRT)theconferenceseriesstartedin1994with IMT1 in Toulouse and has been
continued every other year with IMT2 (Pau 1996) IMT3 (Mons 1998) and IMT4 (Bayreuth 2000).
The next conference IMT5 will be held in 2002 in Lyngby Denmark. Thermodi?usion
alsocalledthermaldi?usionortheLudwig-Sorete?ect - scribes the coupling between a temperature
gradient and a resulting mass ?ux. Although the e?ect was already discovered in the 19th
century by Ludwig and Soret it has gained growing interest during the last years due to
improved - perimentaltechniqueslikestate-of-the-artthermogravitationalcolumns modern
opticalmethods ?owchannels andmicrogravityexperiments tomentiononlya few. We are still far from
a detailed microscopic picture but analytical theories have been improved and the availability
of fast computers and e?cient al-
rithmsfornonequilibriummoleculardynamicssimulationshasprovidedvaluable input from the
theoretical side. TheIMTconferencescoverallaspectsofthermodi?usionfromfundamentals to new
applications. Traditionally the focus has been on the ?uid state ra- ing from mixtures of
simple liquids to more complex systems such as critical mixtures electrolytes polymers
colloidal dispersions or magnetic ?uids. IMT4 tried to widen the scope by including a plenary
lecture about thermodi?usion in ionic solids. Scienti?c input comes from diverse disciplines
such as physics chemistry engineering and geophysics. Sadly Leo Kempers passed away while
this book was being prepared. Many
ofushavelostafriendandrespectedcolleague.Hismanuscripthasbeenbrought into its ?nal state by A.
Shapiro whom we want to thank here.
