Empirical LiK excited state potentials: connecting short range and near dissociation expansions.

We report on a high-resolution spectroscopic survey of 6Li40K molecules near the 2S + 4P dissociation threshold and produce a fully empirical representation for the B1Π potential by connecting available short- and long-range data. The purpose is to identify a suitable intermediate state for a coherent Raman transfer to the absolute ground state, and the creation of a molecular gas with dipolar interactions. Starting from weakly bound ultracold Feshbach molecules, the transition frequencies to twenty-six vibrational states are determined. Our data are combined with long-range measurements [Ridinger et al., EPL, 2011, 96, 33001], and near-dissociation expansions for the spin-orbit coupled potentials are fitted to extract the van der Waals C6 dispersion coefficients. A suitable vibrational level is identified by resolving its Zeeman structure and by comparing the experimentally attained g-factor to our theoretical prediction. Using mass-scaling of the short-range data for the B1Π [Pashov et al., Chem. Phys. Lett., 1998, 292, 615620] and an updated value for its depth, we model the short- and the long-range data simultaneously and produce a Rydberg-Klein-Rees curve covering the entire range.

Stability of a frequency-comb-based transfer-lock using a passive Fabry-Perot resonator.

We report on a transfer-lock laser frequency stabilization that utilizes a frequency comb (FC) and a radio frequency counter referenced to a GPS frequency standard to compensate for the frequency drifts of two lasers, which are locked to a single passive Fabry-Perot resonator (FPR). The method requires only one optical phase lock with the FC and allows transfer locking of lasers at wavelengths beyond the usable range of the FC. To attain a large frequency tuning range for the lasers, we implement optical serrodyning. We further demonstrate an efficient scheme to suppress residual amplitude modulation, thereby improving the stability of the Pound-Drever-Hall lock used in this case. The absolute frequency stability was found to be better than 2×10-13 on timescales up to 300 s. Hence, together with the frequency stability on short timescales provided by the FPR, this scheme facilitates coherent Raman spectroscopy as needed for an example for the production of ultracold dipolar heteronuclear molecules.

Statins may not protect against vasospasm in subarachnoid haemorrhage.

Statins have been shown in two recent small phase I/II trials to be associated with a marked reduction in clinical and transcranial Doppler (TCD) evidence of vasospasm after aneurysmal subarachnoid haemorrhage (SAH). The purpose of this study was to assess the clinical impact of this treatment in a larger number of patients. Fifty-eight individuals were treated in the year before, and 72 patients treated in the year after, the introduction of a 2week course of 40mg/day pravastatin therapy for SAH. Statins did not result in reduced TCD velocities, clinical or angiographic vasospasm, or improvements in global outcome at the time of hospital discharge. A measurable reduction in the rates of vasospasm was expected, based on the size of the effect of statin therapy in the previous small studies. There remains significant uncertainty as to the role of statins in preventing vasospasm after SAH.