2014 We present the experimental evidence of the linear Stark behaviour in an atomic spectrum at low (absolute) electric field strengths on high lying quasi-hydrogenic series of atomic caesium. This is the behaviour which would be observed on hydrogen atoms for any level. It is exhibited here in the 1-15 V/cm range on quasi-hydrogenic atoms, excited, in vapour phase, by a c.w. dye laser to n = ...

The magnetic pitch angle and the magnitude from reversed field pinch plasmas in the Madison symmetric torus (MST) have been routinely obtained from fully resolved motional Stark effect (MSE) spectrum analyses. Recently, the spectrum fit procedure has been improved by initializing and constraining the fit parameters based on the MSE model in the atomic data and analysis structure. A collisional-...

We present an electric field modulated absorption spectroscopy (Stark effect) study of isolated photosystem II reaction center complexes, including a preparation in which the inactive pheophytin H(B) was exchanged for 13(1)-deoxo-13(1)-hydroxy-pheophytin. The results reveal that the Stark spectrum of the Q(x) and Q(y) transitions of the pheophytins has a second-derivative line shape, indicating...

A high-precision spectral motional Stark effect (MSE) diagnostic provides internal magnetic field measurements for Madison Symmetric Torus (MST) plasmas. Currently, MST uses two spatial views--on the magnetic axis and on the midminor (off-axis) radius, the latter added recently. A new analysis scheme has been developed to infer both the pitch angle and the magnitude of the magnetic field from M...

Temperature-controlled, 0.15 nm interference filters were installed on an edge-viewing system of the motional Stark effect (MSE) polarimeter on the DIII-D tokamak. The upgraded system provides a factor of two reduction in the bandpass compared to the previous design, and linear control of the bandpass, which is unaltered by wavelength tuning. With the new system, there is a reduced dependence o...

Giuseppe Pica,1,* Gary Wolfowicz,2,3 Matias Urdampilleta,2 Mike L. W. Thewalt,4 Helge Riemann,5 Nikolai V. Abrosimov,5 Peter Becker,6 Hans-Joachim Pohl,7 John J. L. Morton,2,8 R. N. Bhatt,9 S. A. Lyon,9 and Brendon W. Lovett1,3,* 1SUPA, School of Physics and Astronomy, University of St Andrews, KY16 9SS, United Kingdom 2London Centre for Nanotechnology, University College London, London WC1H 0A...

Two-dimensional black phosphorus (BP) has sparked enormous research interest due to its high carrier mobility, layer-dependent direct bandgap and outstanding in-plane anisotropic properties. BP is one of the few two-dimensional materials where it is possible to tune the bandgap over a wide energy range from the visible up to the infrared. In this article, we report the observation of a giant St...

Coherent optical driving can effectively modify the properties of electronic valleys in transition metal dichalcogenides. Here, we observe a new type of optical Stark effect in monolayer WS2, one that is mediated by intervalley biexcitons under the blue-detuned driving with circularly polarized light. We find that such helical optical driving not only induces an exciton energy downshift at the ...