Femtosecond Dynamics

Welcome to the femtosecond laser lab!


We use femtosecond (fs, 10-15 seconds) laser pulses in the visible and ultraviolet spectral range to investigate photoinduced dynamics in molecules in gas phase or isolated in superfluid helium nanodroplets. After photoexcitation, we ionize the species under investigation with a time-delayed second pulse and detect photoelectrons and photoions in coincidence. The transient changes of the ion- and electron signals tell us about the molecular transition state dynamics.

In particular, we isolate atoms and molecules in helium nanodroplets to learn about the influence of the superfluid environment on the relaxation dynamics. Helium droplets also allow to investigate photochemical processes in a micro solvation environment, consisting of a controlled number of solvent molecules, thereby bridging from gas-phase to solution experiments.

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2017-03-31: New article accepted in Journal of Physics B: Atomic, Molecular and Optical Physics 

We are very happy that our publication "Direct observation of a photochemical activation energy: A case study of acetone photodissociation" is now accepted and also available online in Journal of Physics B: Atomic, Molecular and Optical Physics. The paper discusses a single femtosecond pulse study on the dissociation dynamics in acetone and how the energy after photoexcitation is redistributed within a molecule to induce fragmentation. Link to article


2016-09-01: Project launch: Photoinduced Dynamics in a Quantum Fluid Environment

The FWF project "Photoinduced Dynamics in a Quantum Fluid Environment" (P 29369) starts. We will investigate femtosecond dynamics of simple dopants (atoms and molecules) located inside superfluid helium nanodroplets. The dynamics will be initiated by photoexcitation and probed by photoionization and electron/ion detection.


2016-07-26: New article accepted in J. Phys. Chem. A

Our article entitled "Disentangling Multichannel Photodissociation Dynamics in Acetone by Time-Resolved Photoelectron-Photoion Coincidence Spectroscopy" is accepted for publication in The Journal of Physical Chemistry A. This work applies femtosecond photoelectron-photoion coincidence spectroscopy to study relaxation and fragmentation dynamics of highlying Rydberg states in isolated acetone molecules. Link to article



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Selected Publications

Markus Koch, Pascal Heim, Bernhard Thaler, Markus Kitzler and Wolfgang E. Ernst:
Direct observation of a photochemical activation energy: A case study of acetone photodissociation
Journal of Physics B: Atomic, Molecular and Optical Physic, 2017
link to article

Paul Maierhofer, Markus Bainschab, Bernhard Thaler, Pascal Heim, Wolfgang E. Ernst, Markus Koch:
Disentangling Multichannel Photodissociation Dynamics in Acetone by Time-Resolved Photoelectron-Photoion Coincidence Spectroscopy
The Journal of Physical Chemistry A, 2016, 120, 6418-6423
link to article



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Open Positions

Master project: Femtosecond dynamics in isolated molecules

Many processes in molecules take place on ultrafast (femto- and picosecond) timescales. We investigate such processes in single, isolated molecules with pump-probe femtosecond laser spectroscopy and photoelectron and photoion detection. In particular, coincidence detection of electrons and ions, the novelty of our setup, provides important information about molecular fragmentation.
The aim of this master project is to apply continuously variable excitation and/or probe wavelengths for dynamics studies in acetone molecules. The master student will work in a modern laser lab and acquire a deep insight into molecular processes and dynamics. They will be trained in the following areas: ultrafast laser science, photoelectron and photoion spectroscopy, ultra high vacuum, automated data acquisition and hardware control.
Need more information? - feel free to stop by anytime at our offices (Markus Koch: PHEG092; Pascal Heim, Bernhard Thaler: PHEG050).

Compensation: 2640 €
Contact: Ass. Prof. Markus Koch markus.kochnoSpam@tugraz.at



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Bachelor / Master / PhD Theses

Bernhard Thaler
Ultrafast molecular photodissociation dynamics studied with single-pulse femtosecond photoelectron-photoion-coincidence spectroscopy
Master's Thesis, March 2017

Markus Bainschab
Multiphoton Ionization Channels in Molecules Investigated by Photoelectron-Photoion-Coincidence Spectroscopy
Master's Thesis, June 2016

Paul Maierhofer
Femtosecond Photodissociation Dynamics in Molecules studied by Time-Resolved Photoelectron-Photoion-Coincidence Spectroscopy
Master's Thesis, July 2016

Franz Koberg
Femtosecond Photoelectron and Photoion Spectrometer
Bachelor Thesis, May 2015



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Former Members

Franz Koberg

Markus Bainschab, DI BSc

Paul Maierhofer, DI BSc

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All images © TU Graz/Institute of Experimental Physics

Group members

Ass.Prof. Markus Koch
group leader
+43 (316) 873-8161 / -8163

Prof. Wolfgang E. Ernst
head of the institute
+43 (316) 873-8140

Bernhard Thaler
PhD student
+43 (316) 873-8167 / -8163
Stefan Cesnik
master student
+43 (316) 873-8167 / -8163

Pascal Heim
master student
+43 (316) 873-8167 / -8163

Sascha Ranftl
master student
+43 (316) 873-8167 / -8163

Leonhard Treiber
master student
+43 (316) 873-8167 / -8163