Home Page of Prof. em. Dr. Dr. h.c. E.W. Schlag

Lehrstuhl für Physikalische und Theoretische Chemie
der Technischen Universität München
Lichtenbergstr. 4, D-85748 Garching, Germany
Phone:+49 89 289 13384 / +49 3614812 Fax:+49 89 289 13389
Mail to:  schlag@mytum.de     Impressum

Professor of physical chemistry




1965    Alfred P. Sloan Fellow

1984     Elected Fellow of the American Physical Society

1985     John Wilfred Linnett visiting professor of chemistry, Cambridge University

1987     Woodward Lecturer, Yale University

1988    Doctor of Philosophy Honoris Causa, Hebrew University, Jerusalem

1988     Fritz Haber Lecturer, Hebrew University of Jerusalem

1990     Ames Lecturer, University of Edinburgh

1993     Gold Honorary J. Heyrovsky Medal, Academy of Sciences of the Czech Republic, Prague

1994     Invited Lecturer, The Welch Foundation Conference

             "Chemical Dynamics of Transient Species" 

1995     John Wilfred Linnett Visiting Professor of Chemistry University at Cambridge, England

1995     Invited Lecturer, The Solvay Conference

"Photochemistry: Chemical Reactions and their Control on the Femtosecond Time Scale"

1996     Charles M. Knight Lecturer, The University of Akron

1997     Bonhoeffer-Eucken-Scheibe lecturer

1998     James-Franck lecturer, Israel Academy of Sciences, Jerusalem

1999     Edward K.C. Lee Distinguished Lecturer in honor of Professor E.K.C. Lee , University of California, Irvine, USA

1999     CRC Lecturer California Institute of Technology

2001     Heisenberg Medal of the Alexander von Humboldt Foundation

2009    The 25th  anniversary of ZEKE Spectroscopy was honored in a Symposium at the National Meeting of the American Chemical Society in August 2009 in Washington DC: managed by D. Neumark, Berkeley and Masaaki Fujii  Japan

2016     Emeritus of Excellence, TUM

Scientific Academies:


1978      Election to Membership in the Bayerische Akademie der Wissenschaften

1998     Election to Membership in the Academia Europea


Research Focus

To summarize the contributions in one sentence one would state that; we pioneered experiments in chemical spectroscopy by the use of tunable lasers.

Current Interests:


Charge migration in protein structures - molecular wires


ZEKE spectroscopy is based on the discovery that Rydberg states with high quantum number, very close to ionization that display extremely long lifetimes. This is due to slight perturbations from external fields. This was first observed in a doctoral thesis of Peatman at Northwestern. The high resolution laser result was then confirmed in the doctoral thesis of Sander in Munich.

ZEKE- a new spectroscopy for molecular ions, ie. molecules in which one electron is removed so that they are considered ionized. Many chemical reactions occur in the ionized state. Hence it is important to know their structure. The structure of such molecular ions will be different from the structure of the neutral molecules. The spectroscopy of ions has so far been done by analyzing the electron emitted from the neutral molecule. Such Photoelectron Spectroscopy is inherently fraught with difficulties since it is very difficult to measure the electron velocities. This is an inherent problem related to the fact that all electron measuring devices require surfaces to define a potential. However, a surface has a structure, and as such an inherent and uneven potential that cannot be cancelled. Hence the resolution of all such devices is extremely limited.

Our method is based on the measurement of the last neutral Rydberg state prior to ionization. When an atom is excited with ever higher energy it will go into ever higher orbits, until it eventually ionizes. This is called a Rydberg series.The same is true for molecules. But here the final convergence of the excitation energy can lead to a vibrational or even rotational state of the molecule. Hence a molecule has thousands of ionized states, each with it own Rydberg series.

We discovered that the many ionized states of a molecule are not so very short lived, as it was described in the literature, but rather the very highest states, just before ionization could be quite long lived. This has to do with the coupling of the surrounding fields, created by other ions. This coupling changes the quantum states of the molecule into an orbit that avoids the core, and as such forms a long lived state. A molecule can only become short lived if its electron goes near the core. Hence we discovered that very high Rydberg states bear the signature of being very long lived. Hence our ZEKEspectroscopy ionizes the system with a high energy photon, but delays the extraction until only the long lived molecules survive. Then by just measuring the remaining current I obtain an extremely high resolution spectrum of the state just below ionization. This state is nor subject to the surface potential problems of photoelectron spectroscopy-

In this way thousands of molecular ions have been measured by this new speoctroscopy with an accuracy thousands of times better than existing methods. This enables us to ask questions on the nature of aromatic molecules and chemical intermediates in chemical reactions.

History of ZEKE

We wanted to measure the spectral energy at which no energy was left in the electron i.e. zero energy electrons. For this we built a 127° Rojinski electron analyzer. This was part of the thesis of William Peatman at Northwestern University in 1969. The slits in the analyzer could not be made too small due to a loss of signal. A group in Chicago chose to solve the problem by accelerating the threshold electrons, which, of course, negated the desire to get at the detector. We discovered that opening the slits increased the signal but it led to a strange and quite puzzling discovery, namely that the resolution was independent of the slit width. We then discovered that the analyzer was sensitive to the electrons positioned at the focus and not those of zero energy. We then constructed a parallel plate analyzer which produced the same resolution. We discovered that we now had a steradian analyzer that selected threshold electrons as a new principle. This was the birth of ZEKE spectroscopy. All this was part of Peatman thesis. It was done with a CW source from an Argon discharge and a McPherson monochromator outfitted with a Vacuum UV Al coated Schmid-Cassegrain confocal mirror system constructed for us at the observatory in Wisconsin. This work was done at Northwestern in a group with Tomas Baer, Paul Marie-Guyon and Tommy Borne, early work on steradiency was also done at Argonne by J.Berkowitz, W. Chupka and R. Spohr.

1971 I moved to the Technische Universität Munich and started work with dye lasers which had just become available. Using multiphoton excitation as developed together with the Neusser group the ionization of the ZEKE states was pursued in a new group with Müller-Dethlefs. We then hit on the idea of separating the ions not in space but now in time. Martin Sander was a new graduate student in 1984 assigned to attempt pulse delay studies. This was not possible in the Peatman CW work. The success was dramatic and it has become the method of preference. We later developed the theory started by Leonid Baranov, a student with Raphy Levine. We further tested the results to study the effect of magnetic fields with A. Held.

In short ZEKE spectroscopy employs optical Rydberg spectra to study electron spectra at thresholds and thus avoids the inevitable field effects from electrostatic analyzers. The improvement in resolution is thus many orders of magnitude over any method requiring electrostatic plates. Thus even though CW sources correctly identified ZEKE states by steradial analysis the advent of pulsed laser delay in 1984 enabled Sander et al. to greatly simplify the method and improve the accuracy of electron ionization by many orders of magnitude.
(E.W.Schlag ZEKE Spectroscopy Cambridge University Press 1998)


Dr. George H. Atkinson
Kontakt-Adresse: University of Arizona, Tucson, USA
Fachgebiet: Spektroskopie, Laserphysik, -spektroskopie

Prof. Dr. Joseph BelBruno
Kontakt-Adresse: Dartmouth College, Hanover, USA
Fachgebiet: Physikal. Chemie, Werkstoffwissenschaften

Prof. Dr. Kit Hansell Bowen
Kontakt-Adresse: Johns Hopkins University, Baltimore, USA
Fachgebiet: Physikal. Chemie

Dr. Nasser Chelouah
Kontakt-Adresse: Bauhaus-Universität Weimar, Weimar, Deutschland
Fachgebiet: Baustoffkunde (Bauingenieurwesen)

Dr. Leslie Andrew Chewter
Kontakt-Adresse: Shell Research and Technology Centre, Amsterdam, Niederlande
Fachgebiet: Petrochemie, Physikal. Chemie

Prof. Dr. Hai-Lung Dai
Kontakt-Adresse: Temple University, Philadelphia, USA
Fachgebiet: Grenzflächenchemie, Laserphysik, -spektroskopie, Spektroskopie

Prof. Dr. Edward R. Grant
Kontakt-Adresse: University of British Columbia, Vancouver, Kanada
Fachgebiet: Spektroskopie, Atom- und Molekülphysik

Dr. Johannes Hecker Denschlag
Kontakt-Adresse: Universität Ulm, Ulm, Deutschland
Fachgebiet: Atom- und Molekülphysik, Elektronen-, Quantenoptik

Dr. Friedhelm C. Hummel
Kontakt-Adresse: Universität Hamburg, Hamburg, Deutschland
Fachgebiet: Neurophysiologie, Neurophysiologie, Neurologie

Prof. Dr. Sergey Yul'evich Ketkov
Kontakt-Adresse: Russian Academy of Sciences, Nizhny Novgorod, Russische Föderation
Fachgebiet: Spektroskopie, Nichtmetall- und metallorgan. Chemie

Prof. Dr. Gary R. Kinsel
Kontakt-Adresse: Southern Illinois University at Carbondale, Carbondale, USA
Fachgebiet: Analytische Chemie, Physikal. Chemie

Prof. Dr. Robert L. Letsinger
Kontakt-Adresse: Northwestern University, Evanston, USA
Fachgebiet: Organ. Chemie

Prof. Dr. Sheng H. Lin
Kontakt-Adresse: Arizona State University, Tempe, USA
Fachgebiet: Theor. physikal. Chemie

Prof. Dr. Rudolph A. Marcus
Kontakt-Adresse: California Institute of Technology, Pasadena, USA
Fachgebiet: Physikal. Chemie

Prof. Dr. Shaul Mukamel
Kontakt-Adresse: University of California, Irvine, Irvine, USA
Fachgebiet: Spektroskopie, Theor. physikal. Chemie

Prof. Dr. Daniel M. Neumark
Kontakt-Adresse: University of California, Berkeley, Berkeley, USA
Fachgebiet: Spektroskopie

Prof. Dr. Joseph W. Nibler
Kontakt-Adresse: Oregon State University, Corvallis, USA
Fachgebiet: Spektroskopie

Prof. Dr. Charles S. Parmenter
Kontakt-Adresse: Indiana University, Bloomington, USA
Fachgebiet: Spektroskopie

Prof. Dr. William B. Peatman
Kontakt-Adresse: , ,
Fachgebiet: Spektroskopie

Prof. Dr. Egmont R. Rohwer
Kontakt-Adresse: University of Pretoria, Pretoria, Südafrika
Fachgebiet: Analytische Chemie, Laserphysik, -spektroskopie, Physikal. Chemie

Prof. Dr. Frank Sherwood Rowland
Kontakt-Adresse: University of California, Irvine, Irvine, USA
Fachgebiet: Reaktionskinetik und Katalyse

Dr. Peter Schlagheck
Kontakt-Adresse: Universität Regensburg, Regensburg, Deutschland
Fachgebiet: Theor. Physik

Prof. Dr. Hiroshi Sekiya
Kontakt-Adresse: Kyushu University, Fukuoka, Japan
Fachgebiet: Reaktionskinetik und Katalyse

Dr. Alice May Smith-Gicklhorn
Kontakt-Adresse: , ,
Fachgebiet: Spektroskopie

Dr. Chahan Yeretzian
Kontakt-Adresse: Zürcher Hochschule für Angwandte Wissenschaften, Wädenswil, Schweiz
Fachgebiet: Physikal. Chemie

Prof. Dr. Ahmed H. Zewail
Kontakt-Adresse: California Institute of Technology, Pasadena, USA
Fachgebiet: Spektroskopie


Other fields:

Multiphoton ionization mass spectrometry

High resolution sub-Doppler molecular spectroscopy and dynamics

Spectroscopy and kinetics of molecular ions

Dynamics of photoexcited states and van der Waal's molecules

Synchrotron radiation experiments on molecular ions, inner shell excitation


Scientific Synopsis click here


The work in the group has over many years been involved with initiating new methods in Multiphoton Spectroscopy of Molecules such as the initial work on REMPI in 1978--parallel with the late Richard Bernstein , a technique in use in most laser laborartories, the initial work on high resolution ZEKE Spectroscopy of molecular ions , REflecting high resolution time of flight mass spectroscopy TOF with lasers in particular the variable reflecting field technique. More recently the effort has turned to molecular dynamics calculations of elementary processes in peptides, such as hydrogen bonds with entropy contributions from solvent effects , pairwise interactions of amino acid residues, etc.

1. ZEKE Spectroscopy
a) Molecular cations together with mass analysis (MATI) employing a new, long path analyzer
b) Mechanism of ZEKE spectroscopy
c) Anion ZEKE spectroscopy - metal-organic metastables
d) Photoelectron spectroscopy with a new analyzer

ZEKE Spectroscopy by E.W. Schlag, Cambridge Univeristy Press 1998

2. Molecular clusters and van der Waals molecules
a) structural effects, ab-initio calculations
b) hole burning spectroscopy of benzene dimer, etc.

3. Multiphoton Ionization Mass Spectrometry REMPI (1978)
4. Synchotron radiation experiments
5. Dynamics of molecular ions in photoexcited states
6. Dynamics of Protein Structure -- the interaction of charge and reactivity in polypeptides
7. Laser vaporation of biomolecules
8. Pump/Probe picosecond and femtosecond spectroscopy


"Multiphoton Spectroscopy of Molecules"
S. H. Lin, Y. Fujimura, H. J. Neusser and E. W. Schlag
Academic Press, 1984

"Time of Flight Mass Spectrometry and its Applications"
E. W. Schlag
Elsevier, 1994

"ZEKE Spectroscopy"
E. W. Schlag
Cambridge University Press, 1998 (ISBN 9780521675642)

Charge transport in proteins


Dieser Webauftritt wird von dem Lehrstuhl für Physikalische Chemie, Lichtenbergstraße 4, 85748 Garching b. München betrieben. Die dabei verarbeiteten personenbezogenen Daten unterliegen den geltenden datenschutzrechtlichen Bestimmungen, insbesondere dem Bayerischen Datenschutzgesetz (BayDSG) und dem Telemediengesetz (TMG).

Nachfolgend informieren wir Sie über Art, Umfang und Zweck der Erhebung und Verwendung personenbezogener Daten. Diese Informationen können jederzeit von unserer Webseite abgerufen werden.


Wenn Sie diese oder andere Internetseiten aufrufen, übermitteln Sie über Ihren Internetbrowser Daten an unseren Webserver. Die folgenden Daten werden während einer laufenden Verbindung zur Kommunikation zwischen Ihrem Internetbrowser und dem Webserver temporär in einer Logdatei aufgezeichnet:

  • IP-Adresse des anfragenden Rechners
  • Datum und Uhrzeit des Zugriffs
  • Name, URL und übertragene Datenmenge der abgerufenen Datei
  • Zugriffsstatus (angeforderte Datei übertragen, nicht gefunden etc.)
  • Erkennungsdaten des verwendeten Browser- und Betriebssystems (sofern vom anfragenden Webbrowser übermittelt)
  • Webseite, von der aus der Zugriff erfolgte (sofern vom anfragenden Webbrowser übermittelt)

Die Daten in dieser Logdatei werden sowohl automatisch als auch in Einzelfällen manuell ausgewertet, um Angriffe auf die Webserver erkennen und entsprechend reagieren zu können. Logeinträge, die älter als sieben Tage sind, werden automatisiert gelöscht. Die in den Logeinträgen enthaltenen IP-Adressen werden nicht mit anderen Datenbeständen zusammengeführt, so dass kein Rückschluss auf einzelne Personen möglich ist.


Unsere Webseiten enthalten zum Teil Links auf Webseiten anderer Organisationen und Privatpersonen. Auf die Gestaltung und die Inhalte dieser Webseiten haben wir keinen Einfluss und wir können nicht kontrollieren, wie deren Anbieter mit Ihren personenbezogenen Daten umgehen.

Gültigkeit und Aktualität

Mit der Nutzung unserer Webserver willigen Sie in die oben beschriebene Datenverwendung ein. Diese Datenschutzerklärung ist unmittelbar gültig und ersetzt alle früheren Erklärungen.
Durch die Weiterentwicklung unserer Webseiten kann es notwendig werden, diese Datenschutzerklärung zu überarbeiten. Wir behalten uns vor, die Datenschutzerklärung jederzeit mit Wirkung für die Zukunft zu ändern, und empfehlen Ihnen, sich die jeweils aktuelle Datenschutzerklärung von Zeit zu Zeit erneut durchzulesen.

Mail to:  schlag@mytum.de