Publications de Stefan Haacke | EPFL Graph Search

Coherent ultrafast torsional motion and isomerization of a biomimetic dipolar photoswitch

Stefan Haacke, Majed Chergui, Olivier Christian Bräm, Andrea Cannizzo

Femtosecond fluorescence up-conversion, UV-Vis and IR transient absorption spectroscopy are used to study the photo-isomerization dynamics of a new type of zwitterionic photoswitch based on a N-alkylated indanylidene pyrroline Schiff base framework (ZW-NAI ...

Royal Society of Chemistry2010

Functional electric field changes in photoactivated proteins revealed by ultrafast Stark spectroscopy of the Trp residues

Stefan Haacke, Majed Chergui, Frank van Mourik, Erwin Portuondo Campa, Andrea Cannizzo

Ultrafast transient absorption spectroscopy of wild-type bacteriorhodopsin (WT bR) and 2 tryptophan mutants (W86F and W182F) is performed with visible light excitation (pump) and UV probe. The aim is to investigate the photoinduced change in the charge dis ...

2009

Heterogeneity and relaxation dynamics of the photoexcited retianl Schiff base cation in solution

Stefan Haacke, Majed Chergui, Goran Zgrablic

We present steady-state and broadband femtosecond fluorescence spectra of the protonated Schiff base of retinal in various protic and aprotic solvents, as a function of the excitation wavelength. A detailed spectral decomposition of the time-resolved fluor ...

2009

An artificial molecular switch that mimics the visual pigment and completes its photocycle in picoseconds

Stefan Haacke, Majed Chergui, Andrea Cannizzo

Single mols. that act as light-energy transducers (e.g., converting the energy of a photon into at.-level mech. motion) are examples of minimal mol. devices. Here, we focus on a mol. switch designed by merging a conformationally locked diarylidene skeleton ...

National Academy of Sciences2008

On the excitation wavelength dependence of the fluorescence of bacteriorhodopsin

Stefan Haacke, Majed Chergui, Selma Schenkl, Erwin Portuondo Campa, Goran Zgrablic

We present a systematic study of the time-integrated fluorescence of native bacteriorhodopsin, as a function of excitation wavelength across the visible absorption band. While the fluorescence max. is unaffected, the spectrum broadens on the high-energy si ...

Elsevier2007

Vibrational coherences of the protonated Schiff base of all-trans-retinal in solution

Stefan Haacke, Majed Chergui, Goran Zgrablic

Modulations in the time gated ultrafast fluorescence of the protonated Schiff base of retinal in various solvents are reported, which reflect the creation and evolution of vibrational wave packets due to the torsional mode of retinal of frequency .apprx.12 ...

2007

Cellular photoperception and photoactive proteins

Stefan Haacke, Majed Chergui

A review. The crucial steps of cellular photoperception are characterized and followed in real time by laser spectroscopy down to a few tens of femtoseconds. The photoactive proteins studied here are involved in major natural processes such as vision (bact ...

2007