Solving the CH_{4}^{-} Riddle: The Fundamental Role of Spin to Explain Metastable Anionic Methane.

Several types of experiments showed the existence of negative methane ions CH_{4}^{-} over a period of 50 years but the nature of this elusive species remains unknown. A benchmark study has shown that the experimentally observed species cannot be described by the attachment of an electron in the doublet ground state of CH_{4}^{-}. Here we find CH_{4}^{-} as being a metastable species in its lowest quartet spin state, a CH_{2}^{-}:H_{2} exciplex with three open shells lying ca.

Observation of Atom-Wave Beats Using a Kerr Modulator for Atom Waves.

A phase modulation puts the atom in a coherent superposition of quantum states with different kinetic energies. We have detected the interference of such modulated waves at the output of our atom interferometer, and we have observed beats at the difference of the modulation frequencies and its harmonics, in good agreement with theory. The phase modulations were produced by a Kerr phase modulator, i.

Note: A passively cooled heat pipe for spectroscopy.

We have developed and characterized a heat pipe for lithium spectroscopy, which is cooled only by air-convection, although its operating temperature is 330 °C: its construction is simple, of moderate cost and it is very reliable. A thermal model proves that heat-pipes without water cooling can be used up to considerably higher temperatures.

Measurement of the He-McKellar-Wilkens topological phase by atom interferometry and test of its independence with atom velocity.

In this Letter, we report a measurement of the He-McKellar-Wilkens (HMW) topological phase by atom interferometry. The experiment is done with our lithium atom interferometer, and in order to suppress the stray effects present in our first experiment, we use optical pumping of the (7)Li atoms in their F=2, m(F)=+2 (or -2) ground state sublevel. In these conditions, the measured phase shift is the sum of the HMW phase and of the Aharonov-Casher phase, which are separated due to their different m(F) dependence.

He-McKellar-Wilkens topological phase in atom interferometry.

We report an experimental test of the topological phase predicted by He and McKellar in 1993 and by Wilkens in 1994: this phase, which appears when an electric dipole propagates in a magnetic field, is connected to the Aharonov-Casher effect by electric-magnetic duality. The He-McKellar-Wilkens phase is quite small, at most 27 mrad in our experiment, and this experiment requires the high phase sensitivity of our atom interferometer with spatially separated arms as well as symmetry reversals such as the direction of the electric and magnetic fields. The measured value of the He-McKellar-Wilkens phase differs by 31% from its theoretical value, a difference possibly due to some as yet uncontrolled systematic errors.

Permanent magnets for Faraday rotators inspired by the design of the magic sphere.

Faraday polarization rotators are commonly used in laser experiments. Most Faraday materials have a nonnegligible absorption, which is a limiting factor for high power laser optical isolators or for intracavity optical diodes. By using a stronger magnetic field and a shorter length of Faraday material, one can obtain the same polarization rotation and a reduced absorption.

Interferometric measurement of the temperature dependence of an index of refraction: application to fused silica.

The light reflected by an uncoated Fabry-Perot etalon presents dark rings which give a very sensitive measurement of the variations of the return optical path in the etalon. By measuring the diameters of these rings as a function of the etalon temperature T, we get a sensitive measurement of the derivative dn/dT of the index of refraction n. We have made this experiment with a fused silica etalon and we have achieved a 2% relative uncertainty on dn/dT, comparable to the uncertainty of the best experiments.

First measurements of the index of refraction of gases for lithium atomic waves.

We report the first measurements of the index of refraction of gases for lithium waves. Using an atom interferometer, we have measured the real and imaginary parts of the index of refraction n for argon, krypton, and xenon as a function of the gas density for several velocities of the lithium beam. The linear dependence of (n-1) with the gas density is well verified.

New spectroscopic data, spin-orbit functions, and global analysis of data on the A 1Sigmau+ and b 3Piu states of Na2.

The lowest electronically excited states of Na2 are of interest as intermediaries in the excitation of higher states and in the development of methods for producing cold molecules. We have compiled previously obtained spectroscopic data on the A 1Sigmau+ and b 3Piu states of Na2 from about 20 sources, both published and unpublished, together with new sub-Doppler linewidth measurements of about 15,000 A<--X transitions using polarization spectroscopy. We also present new ab initio results for the diagonal and off-diagonal spin-orbit functions.

Parallel temperatures in supersonic beams: ultracooling of light atoms seeded in a heavier carrier gas.

Supersonic expansion is a very powerful tool to produce an atomic beam with a well defined velocity and, by seeding a test gas in such an expansion, the energy of the test gas can be transferred, at least partially, to the very-low-temperature carrier gas. The case usually studied is the one of a heavy gas seeded in a light carrier gas and, in this case, the parallel temperature of the seeded gas is always larger than the one of the carrier gas. In the present paper, we study the opposite case which has received less attention: when a light gas is seeded in a heavier carrier gas, the parallel temperature can be substantially lower for the seeded gas than for the carrier gas.

[Intracranial subdural hematoma after obstetric dural puncture].

The authors report a case of subdural haematoma (HSD), which occurred following epidural analgesia for labour, complicated by post dural puncture headache (PDPH). A 26-year-old woman displayed a typical PDPH following epidural anaesthesia. On the sixth day, she was given a blood patch (BP), which was partially efficacious.

[Sheehan's syndrome: a recurrent obstetrical complication].

Case report of a 25-year-old primigravida who sustained a necrosis of the anterior pituitary gland after a haemorrhagic Caesarean section. The diagnosis was delayed, as the early symptoms (apathy, anorexia, nausea, orthostatic hypotension and hypoglycaemia) were imputed to more usual causes.

[Interactions between naltrexone, an opioid antagonist, and opioids administered during general anesthesia].

We report a case of a probable interaction between sufentanil and naltrexone, an oral long acting opioid antagonist, prescribed for maintenance of abstinence in alcoholics and opioid addicts. The interaction resulted in an antagonisation of the effects of sufentanil and the necessity to increase the dosage. Anaesthetists should be aware of this potential drug interaction.

[Catheter rupture at the site of implantation: a rare accident? Apropos of 2 observations].

Seventy three venous access ports of the same type have been implanted recently in our hospital. We have observed two cases of catheter's rupture. Both accidents show a lot of similarities: material of the same trade mark; same way of implantation: right subclavian vein; rupture before one year; rupture at the point of entry of the subclavian vein; migration of the distal part of catheter; withdrawal of this part by right femoral vein's catheterism.