Giorgio Carelli

A REVIEW OF OPTICALLY PUMPED FAR-INFRARED LASER LINES FROM METHANOL ISOTOPES

The technique of optical pumping in polar molecules is the most efficient for Far-Infrared (FIR) laser generation, providing also a versatile and powerful tool for molecular spectroscopy in this spectral region. Methanol (CH3OH) and its isotopic varieties are the best media for optically pumped FIR laser, with over thousand lines observed, and the most widely used for investigations and applications. In this sense, it is important organize and make available catalogues of FIR laser lines as complete as possible. Since the last critical reviews of 1984 [1] on methanol and its isotopic varieties [2,3,4], over hundred papers have been published dealing with hundreds of new FIR laser lines. In 1992 a review of FIR laser lines from CH3OH was presented [5]. In this communication we extend this work to the other methanol isotopes, namely CH3OD, CD3OH, CD3OD,13CH3OH,13CD3OH,13CD3OD, CH318OH, CH2DOH, CHD2OH and CH2DOD.

Measuring Gravito-magnetic Effects by Multi Ring-Laser Gyroscope

SUMMARY We propose an under-ground experiment to detect the general relativistic effects due to the curvature of space-time around the Earth (de Sitter effect) and to rotation of the planet (dragging of the inertial frames or Lense-Thirring effect). It is based on the comparison between the IERS value of the Earth rotation vector and corresponding measurements obtained by a tri-axial laser detector of rotation. The proposed detector consists of six large ring-lasers arranged along three orthogonal axes. In about two years of data taking, the 1% sensitivity required for the measurement of the Lense-Thirring drag can be reached with square rings of 6

New large offset far-infrared laser lines from CD3OH

m

Solid-state power supply for gas lasers

side, assuming a shot noise limited sensitivity (

Heterodyne frequency measurements of FIR laser lines around 1.2 and 1.6 THz

20 prad/s/\sqrt{Hz}

IR and FIR spectroscopy of 13CD3OH around the 10P(22) and 10P(24) CO2 laser lines: New FIR laser emissions, frequency measurements and assignments

). The multi-gyros system, composed of rings whose planes are perpendicular to one or the other of three orthogonal axes, can be built in several ways. Here, we consider cubic and octahedron structures. The symmetries of the proposed configurations provide mathematical relations that can be used to study the stability of the scale factors, the relative orientations or the ring-laser planes, very important to get rid of systematics in long-term measurements, which are required in order to determine the relativistic effects.

CH318OH: FIR laser line frequency measurements and assignments

The CD3OH molecule has been investigated for new far-infrared laser lines by optically pumping with a cw waveguide CO2 laser. The increased tunability (300 MHz) with respect to a conventional CO2 laser permits to pump many new CD3OH lines. As a consequence 108 new laser lines have been discovered, ranging from 42.9 to 1155 μm in wavelength. On some lines the effect of an electric Stark field has been investigated demonstrating a laser frequency tuning. The total number of known FIR laser lines from CD3OH is increased to about 340 making this molecule the most prolific together with CH3OH.

Frequency and efficiency measurements on FIR laser lines close to the N+ 3P2-3P1 transition

A novel pulsed power supply for gas lasers is presented. The device uses only solid state components and is based on a capacitor bank discharge. Fast switching of the discharge is triggered by an insulated gate bipolar transistor. The terminal section of the power supply is a transformer designed to match the reactive capacitance of a gas discharge. Strokes up to 30 kV and 30 mA are achieved across the secondary windings of this transformer. The power supply delivers high voltage pulses with a duration between 0.5 and 50 μs and a repetition rate up to some kHz. The power supply has been tested on a longitudinal discharge quasi-cw regime CO2 laser. Laser pulses were generated with a duration down to the microseconds region, a peak power exceeding some kilowatts, and a repetition rate ranging from 200 Hz to a few kHz.

A new pulsed CO2 laser yielding new FIR laser lines from CH3OD pumped by the 10P and 10HP lines

We present the frequency measurements of 14 far-infrared (FIR) laser lines. We use the heterodyne technique of mixing FIR laser transitions and microwave radiation on a MIM point contact diode to determine the FIR frequencies. The main motivation was to measure the frequency of laser lines of metrological interest, around the 1.6 and 1.2 THz regions. We also present 15 new FIR laser lines we found while performing the frequency measurements, with wavelengths ranging from 90 /spl mu/m to 819.2 /spl mu/m. All of them are characterized in wavelength, polarization, intensity, working pressure and absorption offset. >

Optically pumped /sup 13/CD/sub 3/OH: far infrared laser lines and assignment

By using high resolution infrared Fourier transform data on 13CD3OH and the 10P(22) and 10P(24) lines of a waveguide CO2 laser to optically pump this methanol isotope, eight new FIR laser lines were observed. The frequencies of five laser lines were directly measured by heterodyne detection with already known laser lines. Particularly interesting are the lines pumped by the 10P(24) line, since a triade of emissions could be completely assigned.