Hauer-lab

From a theoretical perspective, there is no reason that these timescales must be the same. Yet, I don't buy into accidental agreements.. We'll look into this some more.

Hi Maya! The biggest surprise was that population transfer between two degenerate states in the square symmetric molecule happens at exactly the same timescale (60 fs) as electronic dephasing, i.e. decay of the superposition of those two states. We are trying to find out if this is a coincidence.

Fluorescence upconversion vs. NOPA-fluorescence. Pros and cons for each method towards 2D fluorescence excitation spectroscopy (2D-FLEX). Read about it here:
towards 2D fluorescence excitation spectroscopy (2D-FLEX).
links.springernature.com/f/a/EuGC_l2r...
🧪

Broadband shot-to-shot transient absorption anisotropy Transient absorption (TA) is the most widespread method to follow ultrafast dynamics in molecules and materials. The related method of TA anisotropy (TAA) repor

Transient anisotropy is great because it lets you measure electronic dephasing dynamics in square symmetric molecules. Here is how (featured in The Journal of Chemical Physics): pubs.aip.org/aip/jcp/arti... #ChemSky

Fluorescence-Detected Pump–Probe Spectroscopy for Artifact-Free Detection of Stokes Shift Dynamics Fluorescence-detected pump–probe (F-PP) spectroscopy is a recently developed method to study excited-state dynamics. F-PP combines the temporal resolution of conventional transient absorption (TA) spe...

Here is how to measure artefact-free Stokes shift dynamics. With sub-20 femtosecond time resolution: pubs.acs.org/doi/10.1021/...

Dear ydnew.bsky.social, can you please add me to the Bluesky sciences feed. Here is my staff homepage: www.ch.nat.tum.de/dynspec/team and my ORCID: orcid.org/my-orcid?orc.... Thank you!

Oxetane Cleavage Pathways in the Excited State: Photochemical Kinetic Resolution as an Approach to Enantiopure Oxetanes Chiral spirocyclic oxetanes [2-oxo-spiro(3H-indole-3,2′-oxetanes)] were subjected to irradiation in the presence of a chiral thioxanthone catalyst (5 mol %) at λ = 398 nm. An efficient kinetic resolution was observed, which led to an enrichment of one oxetane enantiomer as the major enantiomer (15 examples, 37−50% yield, 93−99% ee). The minor enantiomer underwent decomposition, and the decomposition products were carefully analyzed. They arise from a photocycloreversion (retro-Paternò–Büchi reaction) into a carbonyl component and an olefin. The cycloreversion offers two cleavage pathways depending on whether a C−O bond scission or a C−C bond scission occurs at the spirocyclic carbon atom. The course of this reaction was elucidated by a suite of mechanistic, spectroscopic, and quantum chemical methods. In the absence of a catalyst, cleavage occurs exclusively by initial C−O bond scission, leading to formaldehyde and a tetrasubstituted olefin as cleavage products. Time-resolved spectroscopy on the femtosecond/picosecond time scale, synthetic experiments, and calculations suggest the reaction to occur from the first excited singlet state (S1). In the presence of a sensitizer, triplet states are populated, and the first excited triplet state (T1) is responsible for cleavage into an isatin and a 1,1-diarylethene by an initial C−C bond scission. The kinetic resolution is explained by the chiral catalyst recruiting predominantly one enantiomer of the spirocyclic oxindole. A two-point hydrogen-bonding interaction is responsible for the recognition of this enantiomer, as corroborated by NMR titration studies and quantum chemical calculations. Transient absorption studies on the nanosecond/microsecond time scale allowed for observing the quenching of the catalyst triplet by either one of the two oxetane enantiomers with a slight preference for the minor enantiomer. In a competing situation with both enantiomers present, energy transfer to the major enantiomer is suppressed initially by the better-binding minor enantiomer and─as the reaction progresses─by oxindole fragmentation products blocking the binding site of the catalyst.

🧪 #science
New publication in JACS! pubs.acs.org/doi/full/10.... We show how a photoreaction can lead to enantiopure products — mechanistic work included.

Photoredox capacity expanded by the Cu site of CuFe-Mabiq The monometallic Fe-Mabiq and bimetallic CuFe-Mabiq photoredox catalysts feature similar optical spectra and short excited-state lifetimes. Nevertheless, they exhibit markedly different photochemistry...

Here is a new paper from Corinna Hess (U Regensburg) we contributed to: pubs.rsc.org/en/content/a... 🧪 Bimetallic Mabiqs as versatile photoredox catalysts with rich ultrafast dynamics.

Juergen is heading out for the MRS Spring Meeting in Seattle. (www.mrs.org/meetings-eve...). Meeting lots of old friends, and hopefully many new ones.

Quantenphysik im Blattgrün Die Photosynthese – ein grundlegender Prozess für das Leben auf der Erde – birgt noch immer viele Geheimnisse. Ein Forscherteam um Prof. Jürgen Hauer an der TU München hat nun ein faszinierendes Detai...

Photonworld reports on our recent ChemSci article: photonworld.de/nc/de/magazi...

Seriously, can and will Europe and Canada capitalise on US slipping towards fascism? 🧪 #science

We celebrate #InternationalDayofWomenandGirlsinScience with a femtosecond laser experiment run by Miriam and Erika. #science, #photonics

Women are credited less in science than men - Nature The difference between the number of men and women listed as authors on scientific papers and inventors on patents is at least partly attributable to unacknowledged contributions by women scientists.

On #InternationalDayofWomenandGirlsinScience let me remind you that we are NOWHERE NEAR parity. A few examples.

1. Women are credited less in science than men.
www.nature.com/articles/s41...

Here is a recent press release about our work on ultrafast dynamcis in cholorophyll a. #sciencesky, #chemsky, #sciencecommunication, #optics, #photonics

Measurement of Bacterial Headspaces by FT-IR Spectroscopy Reveals Distinct Volatile Organic Compound Signatures Ensuring prompt and precise identification of bacterial pathogens is essential for initiating appropriate antibiotic therapy and combating severe bacterial infections effectively. Traditional microbiological diagnostics, involving initial culturing and subsequent pathogen detection, are often laborious and time-consuming. Even though modern techniques such as Raman spectroscopy, MALDI-TOF, and 16S rRNA PCR have significantly expedited this process, new methods are required for the accurate and fast detection of bacterial pathogens. In this context, using bacterial metabolites for detection is promising as a future diagnostic approach. Fourier-transform infrared spectroscopy was employed in our study to analyze the biochemical composition of gas phases of bacterial isolates. We can characterize individual bacterial strains and identify specific bacteria within mixtures by utilizing volatile-metabolite-based infrared detection techniques. This approach enables rapid identification by discerning distinctive spectral features and intensities for different bacteria, offering new perspectives for bacterial pathogen diagnostics. This technique holds innovative potential to accelerate progress in the field, providing a faster and potentially more precise alternative to conventional diagnostic methods.

Here's our new publication at Analytical Chemistry: doi.org/10.1021/acs..... Congraulations, Kiran Maiti!

We had ourselves a merry little Xmas party. With a touch of Neon. And Minigolf.

Chem Sci accepted our cover suggestion! Soon to be published. Here is a link to the article: pubs.rsc.org/en/content/a...