A traveling wave decelerator for neutral polar molecules

Recently, a decelerator for neutral polar molecules has been presented that operates on the basis of macroscopic, three-dimensional, traveling electrostatic traps (Osterwalder et al., Phys. Rev. A 81, 051401 (2010)). In the present paper, a complete description of this decelerator is given, with emphasis on the electronics and the mechanical design. Experimental results showing the transverse velocity distributions of guided molecules are shown and compared to trajectory simulations. An assessment of non-adiabatic losses is made by comparing the deceleration signals from 13-CO with those from 12-CO and with simulated signals.Comment: 10 pages, 7 figure

First Lasing of the IR FEL at the Fritz-Haber-Institut Berlin

A new mid-infrared FEL has been commissioned at the Fritz-Haber-Institut in Berlin. The oscillator FEL operates with 15 – 50 MeV electrons from a normal-conducting Sband linac. Calculations of the FEL gain and IR-cavity losses predict that lasing will be possible in the wavelength range from less than 4 to more than 50 μm. First lasing was achieved at a wavelength of 16 μm with an electron energy of 28 MeV. At these conditions, lasing was observed over a cavity length scan range of 100 μm

A beetle-type, variable temperature scanning tunneling microscope for video-rate imaging

A setup is described that combines video-rate imaging with temperature variability for a beetle-type scanning tunneling microscope (STM). The STM is operated in the constant height mode. Sinusoidal driving voltages are used for the scan lines; the resulting image distortions are corrected by a straightforward mathematical operation. A phase shifter is used to compensate the time lag between the driving voltage and the tip motion. A preamplifier with a bandwidth of 300 kHz and an rms noise of ~0.1 nA has been developed. Software has been written for data acquisition rates of up to 2 MHz and for saving movies of more than 3700 STM images of 200 × 200 pixels. Frame rates between 10 and 50 frames s−1 have been achieved, where the highest line rates are above the lowest resonance frequency of the STM. The accessible temperature range of 50–500 K is not impaired by the video mode