G. Wiebusch

A Blueprint for Cost‐Efficient Localization Microscopy

Crystal clear: The authors introduce a miniaturized localization microscopy setup based on cost-effective components. They demonstrate its feasibility for subdiffraction resolution fluorescence imaging in resolving different cellular nanostructures. The setup can be used advantageously in practical courses for training students in super-resolution fluorescence microscopy.

Hydrogenic Rydberg atoms in strong magnetic fields: Theoretical and experimental spectra in the transition region from regularity to irregularity

For deuterium Rydberg atoms in a magnetic field of ∼6 T we compare the complete experimental spectrum in the range −190 cm−1 to −20 cm−1 with the positions and oscillator strengths of the corresponding quantum theoretically calculated photoabsorption lines. The agreement is excellent. The range of energy covered extends from the end of thel-mixing regime up to the regions where the approximate integrability of the problem is completely lost, and the corresponding classical system undergoes a transition to chaos.

Semiclassical quantization of three-dimensional quasi-Landau resonances under strong-field mixing

Three-dimensional “regular” quasi-Landau resonances, recently discovered experimentally in the Balmer spectrum of the highly excited hydrogen atom around the ionization limit in external static homogeneous magnetic fields, are investigated theoretically by extending previous classical trajectory calculations to semi-classically. Employing the EBK-method for multidimensional non-separable systems, closed trajectories of the excited electron with the proton as origin are quantized by numerical quadrature of the two-dimensional EBK-integral in cylindrical coordinates. The results are resonances with quantum numbersn=1, 2,... for each closed classical trajectory as functions of both the excitation energyE and field strengthB. The calculations include in particular also the classically chaotic region around the ionization limit with experimentally accessible fields, just the region which has so far defied exact quantum mechanical solution.Based on simple physical arguments for the motion of the highly excited electron, an analytic relation is derived for the (E, B)-dependence of the regular three-dimensional resonances which fits quantitatively the numerical EBK-results.

Precision measurements and exact quantum mechanical calculations for diamagnetic Rydberg states in hydrogen

Precision measurements of photoabsorption lines of atomic hydrogen in magnetic fields up to 6 T are compared with exact quantum mechanical calculations for energies reaching beyond the regime of approximate separability of the Schrodinger equation. The agreement between measurement and calculation is excellent.

Pulse length variation causing spectral distortions in OPO-based hyperspectral coherent Raman scattering microscopy

Picosecond optical parametric oscillators (OPOs) with broad wavelength tunability are frequently used as light sources in hyperspectral coherent Raman scattering (CRS) microscopy. We investigate how changes in the pulse length during OPO wavelength tuning of the pump beam affect hyperspectral CRS imaging. We find that significant distortions of the resulting CRS spectra occur if the OPO is operated without monitoring pulse length variations. By utilizing a custom-written MATLAB based control program to counteract changes in pulse length, normalized and reproducible data sets can be acquired. We demonstrate this by comparing hyperspectral data obtained from pure substances, as well as relevant biological specimens.

Label-free Super-resolution Optical Microscopy of Cellular Dynamics

We demonstrate super-resolved structured illumination microscopy (SR-SIM) of Raman-active samples with 100 nm spatial resolution. By combining SR-SIM with coherent Raman scattering, even biological samples can be visualized with doubled spatial resolution.

Enhancing the Molecular Sensitivity of Coherent Raman Scattering by Doubly-Resonant CARS (DR-CARS)

The sensitivity of Raman scattering methods is limited by their weak scattering cross-section. We show that the application of doubly-resonant CARS will enhance the molecular sensitivity enabling the detection of smaller molecular targets.