Installation A: Tunable Systems

Installation A Task Force: T. Kitsopoulos, C. Kalpouzos

Installation A provides access to a unique combinationof tunable laser sources, with emphasis on the UV. The main laser systems installed in Installation A include five dye lasers pumped by three XeCl excimer lasers. The systems are equipped with nonlinear frequency doubling crystals offering tunability in the wavelength region 205 - 970nm at ~15ns pulsewidth and spectral bandwidth of 0.2 or 0.04cm-1. A number of cw laser systems are also available.

A vacuum ultraviolet coherent radiation source based on four wave mixing in atomic vapours provides further tunability down to 80nm. Frequency up-conversion occurs alternatively in a static cell, heat pipe or gas jet in a windowless arrangement for operation below the LiF threshold (110nm).

Installation A also supports several experimental workstations capable of performing state of the art experiments in atomic and molecular spectroscopy and dynamics. These workstations are equipped with interchangeable instrumentation such as:

  • Novel sources of neutral and charged atoms, molecules, radicals, and clusters: pulsed supersonic nozzles (repetition rates from 1 Hz to 1 kHz), laser ablation/vaporization source, discharge source of ions and radicals and clusters, alkali metal and alkali earth continuous beam source.
  • Mass/charge analyzers: linear and reflectron type time-of-flight mass spectrometers (ranging up to 20.000 amu, resolution of M/D M ~1000), ion mass selectors, quadrupole mass filters.
  • Energy analyzers: spherical sector electrostatic analyzer for ions and electrons, magnetic bottle electron spectrometer, zero kinetic energy electron analyzer.
  • Position sensitive detectors: microchannel plate detectors coupled to resistive, strip and wedges, phosphor screen anodes.
  • Laser field phase shifter: optical delay arrangement for relative phase control of laser fundamental-overtone frequencies. The differentially pumped setup allows for wavelength operation below the LiF limits.
    Optical Rheology: rheological measurements combined with laser based polarimetry in structured fluids under flow induced morphological changes.

All workstations offer manipulation and simultaneous handling for multiple laser beams and provide computer based data acquisition systems. The workstations can be operated under high or ultra-high vacuum conditions, and offer differential pumping capabilities. Their modular design enables facile modification, adapting to the requirements of advanced research applications such as:

  • High resolution single and multiphoton spectroscopy of atoms, molecules, clusters and radicals: rovibrational structure of Rydberg states of molecules, spectroscopy of doubly-excited or inner shell excited atomic autoionizing states, planetary atom spectroscopy, rovibronic structure of molecules, free radicals and clusters.
  • Induced and modified electronic structure: laser induced bound and continuum structure, electromagnetically induced transparency, laser induced stabilization.
  • Laser phase induced effects: Coherent control of ionization/photodissociation yields, branching ratios and angular distributions, coherent control of autoionizing structure.
  • Photofragmentation spectroscopy of neutrals and mass-selected ions: Cross sections, state-selected velocity and angular distribution of photofragments, product branching ratios.
  • Cluster formation, stability, and reactivity: production mechanisms of pure and mixed clusters, spontaneous and collision induced decay, reactive and catalytical properties.
  • Chemical reactivity of neutral and ionic species: integral and differential cross sections, state preparation of reactants and state selected analysis of products.
  • Surface studies: state resolved analysis of desorption and adsorption processes, photochemical heterogeneous catalysis, matrix assisted laser desorption
  • Condensed phase and collective and single-particle dynamic effects: relaxation dynamics and optical anisotropy measurements for a wide range studies in structured fluid systems such as polymers, colloidal suspensions, surfactants and emulsions. Phase transitions in multiphase systems and sheared systems. Aggregation dynamics
  • Laser Induced Fluorescence Spectroscopy (LIFS): Identification of sample composition by means of fluorescence emission measurements
  • Laser induced breakdown spectroscopy (LIBS) : Quantitative elemental analysis of samples by means of emission spectroscopy of the plasma radiation and detection of atomic/molecular species under plasma conditions.
  • Analytical laser mass spectroscopy: Elemental and trace analysis of gaseous and solid samples, laser ablation plume diagnostics.
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